TO OUR READERS                                                           IN THIS ISSUEWe lcome to StarTuned, the          ...
STARTUNEDInformation for the Independent Mercedes-Benz Service ProfessionalSeptember 2008              U.s. $6.00    € 1  ...
You Dont Need One DAS and "Keyless Go" are technological features that make /ife easier as well as increasing the security...
KEYLESS GO                                                                                                   I            ...
The black trunk switch (pictured                                                      here on the right side of the handle...
KEYLESS GO                                                                           the trunk lid so the KG module thinks...
~   - --                                                                     ,                                            ...
FEATURE ARTICLE                                                                Why We Do What We Do                       ...
The Mercedes-Benz coolant                                                               is a cost-competitive option      ...
COOLI NG SYSTEM SERVICEhydrometer. This too l measu res the specificgravity of the coolant, specifically ethyleneglyco l. ...
measured with a refractometer. The temperatureof the coolant mixture still affects the read in g,but since the samp le is ...
COOLING SYSTEM SERVICE    These days with dual heater cores, auxi liary cooling pump motors and externa l cool ing        ...
+                                                                  Distilled                                              ...
Replace - We replace more parts than aftermarket brands.Engineered - Designed to meet original OEM drawings.Manufactured -...
260E          1987-1989                            300CE          1988-1993                           300EITE         1986...
FEATURE ARTICLE                                                                                              aseaml s tran...
ATF                                                       Th e next major step is to check the fluid level.               ...
TRANSMISSION MAINTENANCE                                                            misfire . While driving, you may want ...
- !QI Vehicle    [211.065                             Control unit   [Erc                      VehicleRead out fau n memor...
TRANSM ISSIO N MAIN TEN ANCE                                                               ••• Vehic le                   ...
A Mercedes-Benz should be true to its origins. So              Mer cedes-Benz Classic Center                              ...
Cushioning the BlowIn the last issue of StarTuned we introduced basic air bagmaintenance and repair and as promised, here ...
Mercedes-Benz has always been at the               ETD. The first stage uses an electric motor toforefront of occupancy sa...
COLLISION REPAIR / AIR BAGS PART IIWith a paid subscription to www.startekinfo.com. you can access information such ascomp...
Enticingly graceful and dynamic.                               Strong support, too.           QUALITY                    F...
COLLI SIO N REPAIR / AIR BAGS P RT II                               A                                                     ...
STARTUNEDGENUINE MERCEDES-BENZ PARTS .. , NEARBY                                      Belmont                           Pa...
September 2008 StarTuned Magazine
September 2008 StarTuned Magazine
September 2008 StarTuned Magazine
September 2008 StarTuned Magazine
September 2008 StarTuned Magazine
September 2008 StarTuned Magazine
September 2008 StarTuned Magazine
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September 2008 StarTuned Magazine

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September 2008 Mercedes-Benz StarTuned Magazine

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September 2008 StarTuned Magazine

  1. 1. TO OUR READERS IN THIS ISSUEWe lcome to StarTuned, the 4 KEYLESS GOmagazine for independent servicetechn icians work ing on Mercedes- DAS and "Keyless Go" are technological fea t ures t hatBe nz ve hicles. Your Mercedes-Benz make life easier as well as increasing the security ofdea ler spo nso rs StarTuned and Mercedes-Benz vehicles. It is a continu ing evolut ionprovides the informat ion com ing of various convenience systems. I<nowing how t heseyou r way in each issue. systems work will make diagnosing problems aMercedes-Benz wants to present the profitable experience .information you need to know todiagnose and repair Me rcedes-Benzcars accu rate ly, quickly and the first 12 COOLING SYSTEM SERVICEtime; text, grap hics, on-l ine and other Summer is alm ost upon us, and with the warmertec hnica l sources co mbi ne to make weather come customers hot under the co llar aboutth is possib le. air cond itionin g performance.Feature articles, derived fromapproved company sources , focuson being usefu l an d inte resting. 20 SMOOTH SHIFTINGOur digest of techn ical information One of the benefits of owning a Mercedes-Benz is acan he lp you so lve unantic ipated seamless transfer of power from the engine to the road.prob lems qui ckl y and expertly.Our li st of Mercedes-Be nz dealers To add to the experience adaptive transmiss ion sh iftingcan he lp yo u find Genuine tailors the vehic le to the driver. Lets see howMercedes-Benz Parts. Mercedes-Benz manages these two feats.We want StarTuned to be bothhelpful and informative, so please letus know just what kinds of features 26 CUSHIONING THE BLOW - PART IIand other diagnostic services youd In the last issue of StarTuned we introduced basic airlike to see in it. We ll co nt inu e to bag maintenance and repair and as promised, here isbri ng you se lected se rvice bulletins part two of Cushioning the Blow. Now well take a loo kfrom Mercedes-Benz and articles at the Emergency Tensioning Device (ETD), furthercovering the different systems on testing and checklists.these veh icles . JSend you r suggestions, questionsor comments to us at: 31 GENUINE MERCEDES-BENZ jStarTuned PARTS ... NEARBY I,One Mercedes Drive IMontva le, New Jersey 07645 Wherever you are in the United States, theres a nea rbyPhone : 1 800 225 6262, ext. 7112 source of genu in e factory parts fo r your customerse-ma il: StarTuned@mbusa.com Mercedes-Benz ve hicles.StarTuned is a quar terly publication of Mercedes-Benz USA, LLC (" M BUS A"). No par t o f t h is news let ter may be reprod uced without the express written permission ofMBUSA. Editoria l and Circulation Offices: 598 Pi ne Point Drive, Akron, Oh io 44333. Caution: Vehicle servicing performed by untrained persons could resu lt i n seriousinjury to those persons or others . Information conta ined in this newsletter is in tended for use by tra in ed, professional auto repair techn i c i ans ONLY. Thisinformation is provi ded to inform these technicians o f cond i tions which may occ ur in some veh ic les or to provid e information wh i ch could assistthem in proper serv ic ing of these ve hi c les. Prop erly t rained technician s have the equ ipm ent , tools, sa fety instructions, and know-how to perform repa irscorrect ly and sa fely. If a condition is described, DO NOT assume that a topic covered in th ese pages automat ica lly applies to you r ve hi cle or that your veh icle hasthat condition. StarTuned is a registered trademark of MBUSA.
  2. 2. STARTUNEDInformation for the Independent Mercedes-Benz Service ProfessionalSeptember 2008 U.s. $6.00 € 1 2.50 Volume 8 Numbe r 3Group Publisher Contributing Editor MBUSA Technical Production ManagerChristopher M. Ayers, Jr. Chip Keen Content Advisor Devon Ayerscayers@cmacomm.com ckeen@cmacomm.com Donald Rotolo dayers@cmacomm.com Donald .Rotolo@mbusa.comSenior Project Director Contributing Editor Circulation ManagerTamra Ayers Kerry Jonnson MBUSA Project Manager Joann Turnertayers@cmacomm.com kjonnson@cmacomm.com Stephen Langelotti jtu rner@cmacomm .com Stephen. Langelotti@mbusa.comEditorial Director Contributing Editor List ConsultantBob Freudenberger T Nash om Art Director NFocusbfreud@cmacomm .com tnash@cmacomm .com JefSturm jsturm@cmacomm.com
  3. 3. You Dont Need One DAS and "Keyless Go" are technological features that make /ife easier as well as increasing the security of Mercedes-Benz automobiles. It is a continuing evolution of various Convenience systems. Knowing how these systems work will make diagnosing problems a profitable experience. As with any other computer-controlled We will look into how to determine if the vehicle system , knowing how it works is half the battle has Keyless Go and how it is supposed to of diagnosis. Some of the more high-tech function. Then we will look into diagnosing advancements Mercedes-Benz has to offer its problems when they pop up. owners are DAS (Drive Authorization System) and "Keyless Go ." Both are symphonies of That Is One SmartKey well-orchestrated computer input and output signals creating convenience features With pre-98 DAS (DAS2b) the actual ignition Mercedes-Benz owners have come to expect. key can be separate or is incorporated with the Very often, elaborate computer communication central locking system remote. The key also schemes are required when multiple control houses a transponder. The physical key allows units need to interface to create the desired the ignition lock cylinder to turn, unlocking the effect. First, we will review the components steering wheel. This transponder signal is picked involved, followed by how they work together up by an antenna around the ignition lock cylin- to form the DAS and Keyless Go features . der. If the proper signal is sent to the immobilizer Mercedes-Benz introduced the next evolution of control unit (or early DAS unit), the message is DAS (DAS3) with the SmartKey feature in 98, passed on to the Powertrain CAN and the engine and Keyless Go was introduced to the U.S. is allowed to crank and start. If an incorrect market in 2001 on the 220 and 215 chassis, and signal is sent. the engine may crank for a short in 2003 in the new SL-class, the 230 chassis. time, but fuel will be cut and the engine wont By removing the physical key and pushing down on the grey tab, you can separate the two parts and replace the watch- style battery in the SmartKey. A dead battery will only affect the power door lock features. Cranking and starting the vehicle will not be affected. StarTuned 05
  4. 4. KEYLESS GO I start. Chassis numbers starting with a "1 " (i.e . 163, etc.) maintained th ese separate immobi lizer module/DAS module to control key recognition . After 98, the newer chassis numbers starting with the number "2" (i.e. 21 1, etc.) advanced to the newer DAS3 SmartKey system. These SmartKeys work with an EIS (E lectronic Ignition Switch). This EIS takes the place of the mechanical lock cylinder, substituting an elec- tronic control unit. An electromagnetic coil built into the EIS powers up the SmartKey. The key in turn sends an infrared signal directly to the EIS unit. The SmartKey also contains a radio fre- quency transmitter and an infrared unit for the central locking unit. However, if the battery dies only door locks will be affected. Once the EIS is awake, it sends its information to the SLM (Steering Lock module), the ESM (Electronic Shifter Module), and the Powertrain CAN (ME- Motor Electronics - co ntro l unit), as well as turn- ing on accessory and ignition power to the rest of the vehicle . If the key is not accepted, th e EIS is not unlocked and the key cannot even be turned . From 01 to 03 Mercedes-Benz phased in "Keyless Go." This feature added a card that, if within the proper range, would al low the vehicle to be opened and started without using the mart key. After 2004 the Keyle ss Go card is incorpo- rated in the SmartKey itself. If you feel you may have a prob lem with one of these convenience features, you need to kno w if the vehicle has Keyless Go or not. The fastest way to determine this is to look for the "Start/Stop" on the top of the shifter knob . YouThe Start/Stop engine button on will also notice a push button on the drivers sidetop of the shifter indicates that the door handle for locking the veh icle. Another item to look for is a push button on the rear trun kvehicle has the Keyless Go feature. next to the trunk release handle. Finally, theThe signal is sent to the ESM and Keyless Go card is the last piece you are going to need to verify that it is function ing properly. Nowthen passed on to the Keyless Go lets see what the Keyless Go feature does.module through the CAN. With your This feature performs a few simple tas ks such as activating and deactivating the alarm, lockingscan tool you should be able to and unlocking the vehic le and, of cou rse, startin gcheck this input in either control unit. and stopping the engine. In add iti on to these tasks, it can also allow operation of some con- venience features by turning on accessory power through the EIS (Electronic Ign ition Switch) . One thing that is required here is the Keyless Go card. Make sure the customer drops off th e t wo06 Stal-Tuned
  5. 5. The black trunk switch (pictured here on the right side of the handle) is one of the few direct inputs to the Keyless Go module. Remember, it is only used to lock the vehicle, not unlock it.cards al ong with the vehic le when investigating they wi ll not work. At this point the door hand lesany prob lem with the system . The card can be need to be pu ll ed on once to wake up the KGstowed in the interior cabin of the vehicle or in system and the second pull shou ld unlock andthe trunk to operate the locking and unlocking open the door. Once you have entered the vehi-feature. The card must be in the cabin in order cle with the KG card, pushing on the Start/Stopfor the engine to start. Another item you need to button on the shifter once wakes up the EIShave in your possession is the original DAS3 accessory position. A second push turns onSmartKey (Drive Authorization System 3). It also ignition power. You shou ld be ab le to operate allhas the ability to activate and deactivate the electron ics in the vehic le at this point. Byalarm, and lock and unlock the doors. It will also app lyin g the brake pedal and hitting theover-ride the KG (Keyless Go) card in the event Start/Stop button the engine should startyou are stuck with a ma lfun ction. Advise the providing the ESM indicates it is in the Pa rkcustomers that although they do not need to position. If none of these features work, youuse the SmartKey, they shou ld always have it need to ch eck the KG card and if the card is inwith them as backup. range of the antennas . By hitting the Start/Stop Both t he SmartKey and the KG card have LEDs button again the engine shou ld shut off if theto indicate when they are transmitting. These shifter is still in Park. If the drivers door isLEDs indicate that the batteries are acceptable closed, the EIS wi ll stay on in thein either component. If the LED s do not li ght, accessory position, and if the door is openthen the batteries need to be replaced. In the the EIS shuts off.ca se of the KG card, the LED wi ll in dicate howthe card was last used . If the LED is red, then Knowing the Playersthe vehic le was locked; if green, it was unlocked.Either th e SmartKey or the KG card allows the Now that you know about the SmartKey,owne r to se lect between unlocking only the immobi lizer or DAS units and EIS, we ll move ondrivers door and unlocking all of the doors . to the more comp li cated "Keyless Go." As with Both the door handle and trunk switches most computer contro lled systems the brains areprovide a manual way to lock the veh icle, but not in the control unit. It is almost always mountedfor unloc king. Touching or pulling on the door on the drivers side of the trunk behind the whee lhandle wou ld accomplish this. If during KG house . Like any computer it receives inputs and,locking with the push buttons the wind ows are depending on those inputs, contro ls andopen, the convenience feature will automatica lly manipulates outputs. Some of the inputs areclose them. The door handles have capacitive directly hard-wired into the KG control unit andsensors that discharge when touched. They are other inputs come in through the CAN (Controllerpowered down after three days, so after this time Area Network). Knowing this is important when StarTuned 07
  6. 6. KEYLESS GO the trunk lid so the KG module thinks the trunk Vehicle 1230.475 Control unit IKG is closed. Th ere may also be additional deck lid IActual values switches t hat need to be manipulated to indicate S2I3 (Keyless start and stop pushbutton) Selector lever position that the trunk is c losed. This will allow the sys- Door handle and trunk Ikt contacts Power , up ply tem to lock th e doo rs and arm the alarm. It is Check assignment of transmitter card to key track. also a good was to access the battery to mon i- tor current draw if the battery is going dead over time. If t he KG modu le sees the door handles touc hed or pu ll ed, it will wake up CAN-B (Body CAN) and have t he KG antennas signa l for the KG card. If the card responds, then the CAN wakes up the EIS. The KG card signa ls are received by an antenna in the rear windshield. If th e brake peda l is depressed and the Start/Stop button is pushed the CAN-C communicates that the ESM (E lectronic Sh ifter Module) is in Park and the engine will crank and run. Since the rear wind-The easiest way to check Keyless Go shield is important to the KG system, care mustinputs is through the 50S.Yo u can verify be taken when rep lacing it.that the selector lever is in park, but The Keyless Go system has only a few contro ll ed outputs. Since the pneumatic doorkeep in mind that if that was a problem lock system is too slow to un lock the doors,the customer would have had other there are separate un lock so lenoids in each door. These so lenoids on ly unlock the doorcomplaints such as a no-cronk situation. when the handle is touched or pu lled. Coming In On the CANdiagnosing a problem. Also, knowing what inputsgo where will tell you what control units you have As we discussed earl ier, other important inputsto communicate with using your SDS scan too l. come in thro ugh the CAN. In order to start the In addition, if there is a commun ication prob lem engine, the brake pedal needs to be applied. Thewith the CAN, you may have to fix that first brake switc h in put does not go directly into thebefore you start condemn ing components . KG modu le. To find that wi ring you have to look Some inputs directly wired into the KG unit are at the Traction Control system where the brakethe KG Antennas that are found in the center switch is a direct input. The brake-appl ied signalconsole, each door and a few in the trunk area. passes t hrough the BASI ASR/ ESP contro l unitThese antennas send out a radio signa l looking (depending on how the vehicle is equipped) andfor the KG card . When the KG card wakes up, it continues on to the KG module. In the case of an sends a rep ly radio signal back that the card is 05 230 chassis, can evaluate the wiring diagram the right one for this vehicle. Also, both the push provided with a pa id subscription to button in the door hand le and trunk lock switch- www.startek info.com . The Park and Start inputses are hard wired into the KG modu le. You can do not come in through the CAN, but in ste ad are use your SDS Compact III to monitor these hard- directly wired to the KG module. Thi s changes wired inputs to quickly determine if they are sli ghtly in early 06 and later models with the working properly. Otherwise, you have to check Park and Start inputs being supp lied on a single the wiring directly. This can be time-consuming, wire. Either way, the ESM (E lectronic Selectorand the trunk needs to be open to access the Modu le) receives the switch inputs directly andKG module. You will have to lock the latch on passes them along the CAN to the KG module.08 StarTuned
  7. 7. ~ - -- , -- Small scratches, stone impacts, dents and blemishes - and the customers Mercedes can quickly lose the shine from its exterior. And because that is annoyance enough, we keep the costs for a repair as low as possible - with Mercedes-Benz Small Repair. Special repair methods mean that small appearance defects vanish in next to no time. It goes without saying that our kits meet the high, tested Mercedes-Benz quality standards that you expect. So if your customers are driving around with a small imperfection, it may be able to be repaired with Mercedes-Benz Small Repair. Small Repair Kits are available from your authorized Mercedes-Benz dealer. Training on the Small Repair methods are available from Reliable Automotive Equipment. Please contact Reliable Automotive Equipment to inquire about training your staff to perform these repairs quickly and efficiently.RAE RELIABLE AUTOMOTIVE EQUIPMENT, INC. 1.800.328.7855
  8. 8. FEATURE ARTICLE Why We Do What We Do Put any two different materia ls together and chances are they are going to react with one another. Some reactions will happen quicker t han others, but eventua lly someth ing is going to happen . The same dynamic happens within the cooling system of any engine. In modern engines, alum inu m alloys make up the blocks and cylinder heads. The se aluminum alloys are more reactive than their iron or steel alloy counterparts. Coolants that run through these aluminum components often react with them, breaking down both the coolant and th e alu- minum. The debris from th is reaction gets circulated throughout the cooling system. It often bui ld s up in small cavities found in places like the rad iator and/ or heater core. Eventua ll y, t he passages become blocked and circulation is reduced . These contam inants can also build up on thermostats, po ss ibl y causing them to stick Ask anyone what a "cool ing system service" is and you closed. We all know a closed thermostat willwill probably get the tried-and-true answer of draining and restrict coo lant flow to the engine and resu ltrefilling the coo ling system. Thi s is common ly reduced to in overheatin g.draining the radiator and refil ling it. But what is the pur- To prevent this corrosion effect on coolingpose of servicing the coo ling system? Was the veh icle system component s, we rep lace the coolant. Itoverheating? Will the engine overheat in the fu ture? Th ese removes t he corrosion contaminants anddays, coolant has become much more than the "green restores higher boiling points and lower freezingstuff." Phosphates, organic ac id compounds and other points within the cool ing system. Mercedes-additives add to the confusion: Can I mix this with that? Benz maintenance schedules have you replaceDo I have to flush the whole system? What co lor shou ld the coo lant at 147,000 miles or 15 years. Thesethe coolant be? This may sound si lly, but when you per- maintenance schedu les are dependent on useform some service work (rep lacin g a thermostat) you will of approved a nti-corrosion / anti-freeze coolantslose some coo lant. You need to know what coo lant is and you are required to check the cool ing sys-compatible with what you already have in there . Wi ll you tem at each service. Mercedes-Benz factorypick one of the aftermarket so-ca ll ed all-purpose so lu- coolant (Part # Q 1 03 0002) meets all thetions? Will t he coo lant you use breach the customers requirements to achieve these low-maintenanceexisting warranty? Understanding the requirements of interva ls. Money saved putting in a less expen-Mercedes-Benz ve hicles wi ll make the decision-making sive coolant is often lost in the long run withprocess easier. clogged and corroded components requiring12 StarTuned
  9. 9. The Mercedes-Benz coolant is a cost-competitive option that many of us do not think about. It contains the ® Mercedes Br.tlZ necessary corrosion additives Anticorrosion! and is ethylene glycol-based, Antifreeze AGENT Pnlecls iUli.tJJ.... elBlne frGlIlca ....siOll so we can use a regular c."".,.... .IId IteezinJI .l1li rlllSes ll1e bclllog pOflll. 10 1118 $p.. lII.ati... , ... 1Ie1lllt. P"dIIdB .... at Ito. 325. hydrometer and refractor Q 1 030002 to test it. It is also clear, UrMU,S.,6dm ·3.lBlLIJI1f5 ...... lRII~~.tJlfJUl.F ~lItft-.aEJ . ~.~~ which make contamination easier to spot.replacement, as we ll and add itiona l coo lant cool in g system pressure test is ca ll ed for.flushes. We should all agree that the minim al Commercial testers are ava ila ble from yo ur toolmoney saved on coo lant does not come close to supplier along with the necessary coo ling systemthe cost of a cooling system repa ir. Th e labor adaptors. Simply pump up the system to thetime on a coo ling system services varies from 1.0 rated pressure capacity of the rad iator cap andto 1.5 hours depending on th e model. Lets go see if the pressure drops . If it does, look forover how we are going to test to see if the externa l leaks. You may also want to attach ancoo lant is up to the task . add iti ona l adaptor and check the cap. If you can- not find any externa l leaks, it s t ime to look atA Few Minutes Testing the possibili ty of an internal leak . In th e last iss ue of Star Tuned, testing for head gasket Th e first th in g we are taught about testin g problem s was covered, so look there forcooling systems is a visual check. Look in g at the those answers.coo lant level and the coo lant itself is the first If the coo ling system passes the pressure test,test we should perform. Cool ing systems that are its time to test th e coo lant itself. Mercedes-Benznot up to leve l at some point had a problem. recommends testing th e coo lant at every serviceEither the coolant is leaking out somewhere, or (i .e. oi l change). Thi s can be done one of twoits being used by t he engine. At thi s point a ways. Th e first method invo lves a coo ling system StarTuned 13
  10. 10. COOLI NG SYSTEM SERVICEhydrometer. This too l measu res the specificgravity of the coolant, specifically ethyleneglyco l. This specific gravity is a measurement ofcoo lant concentration. The ideal mixture shou ldbe 50% coo lant and 50% water. This ethylen eglyco l mixtures spec ific gravity wi ll be affectedby the tempe rature of the fluid, therefore acoo lant hyd rometers scale needs to be ca libra t-ed to a specific tem perature. You can use yourinfrared temperature gun to determine theliqu ids te mperatu re and have it match thetemperature of the hydrometer scale. Remember,specific gravity changes with temperature. A50/50 mix of ethylene glycol will have a specificgravity rea ding of 1.057 at about 100 deg. F. Ifthe ve hicle came in and the coo lant was 150deg. F., the same good mixture wou ld yie ld areading of 1.037. If yo ur tool is ca librated to 100deg. F. yo u would think the concentration was35%, so make sure you know what temperatureyo ur hydrometer is cal ibra ted to. Th is too l dra ws coolant into a clear plastic tubewith either we ighted balls of varying density, or asingle float pivoting on a pin. See how many ballsfl oat or how fa r the single float rises and that willindicate the specific gravity of the coo lant. Airbubbles in the samp le affect the buoyancy of thefl oat as we ll . Even expensive hydrometers have Here are the tools of the trade.the same problems. Be lieve it or not, this tool isofte n not precise enough to give you a read in g Mercedes-Benz factory coolant isyo u ca n depend on . Also, the hydrometer cannot ethylene glycol-based, so a coolantbe used on propylene glycol-based coo lantssince two different concentrations can yie ld the hydrometer will work fine. Hydrometerssame specific gravity rea dings . Mercedes-Benz are not the most precise method ofbrand coo lant is based on ethylene glyco l, so youcan use a hydrometer to test it. Remember, measuring concentration. The refractome-te mpe rature variations still have to be taken into ter is much more accurate. Remember,co nsidera tion . Could the re be a better way? It is more expensive than a simp le hydrometer, coolant temperature affects the specificbut the refractometer is very capab le of preci se gravity of the sample. Know what you measureme nts of coo lant concentration . Th e gouge is calibrated for. principle is simp le. As light passes through a liq uid , it will bend a different amount for a differ- ent liqu id, in our case a different coo lant concen- tration. By usi ng a refractometer, you send li ght th ro ugh tje coo lant sample and see how the light bends on the refractometer sca le. You then co mpa re t hat sample to water. Either ethylene glyco l- or propylene glyco l-based coo lants can be14 StarTuned
  11. 11. measured with a refractometer. The temperatureof the coolant mixture still affects the read in g,but since the samp le is so sma ll (on ly a drop)the liquid quickly assumes the temperature ofthe too l. Simply put a drop on th e len s, close the clearcover and point the refra cto meter into a lightsource. A meter of good quality will have yo uca librate it by first samplin g distilled water.Once ca li brated, you can samp le your coo lantand check the conce ntra tion .How We Do What We Do For maintenance or service work, yo u mayneed to rep lace the coo lant. How ca n you dothis qu ick ly and be profitable? The first step in a coo ling system service is todra in the existing coo lant from t he radiator.There is usually a drain va lve on th e drivers sideor passengers side tank of th e radiator. Afterremoving the cap of the coo lant system expan-sion tank (to allow air into th e system), you canraise th e vehicl e. Then, open th e drain plug onthe radiator tank. This will only drain the radiatorand some portion of the water pump andthermosta t hous in g. The next step is to drainthe block. Thi s is often ove rl ooked due to the A vacuum-assist tool can save a lot oflack of kn owledge of where the drain plugs areand acces s to th em. With a paid subscription to time in bleeding the system. Generally,www.startekinfo .com. you can view service Mercedes-Benz engines do not have aprocedure s to locate the drai ns. These plugs arelocated at the base of the water j acket on one or problem with bleeding out air, but thisboth sid es. Th ey will often be difficult to remove, helps eliminate the possibility. Shop airso be careful not to round off the bolt head.This is probably the most time-consuming part often powers up the vacuum pump.of the process. Once the cooling system is in a vacuum, Refilling the system used to be simpl e.Add coo lant to the expa nsion tank and let the a valve is switched and fresh coolant isengine run . If there we re some problems in filling drawn in to fill the vacuum.a system, an old trick was to prop th e thermostatopen with two pieces of aspirin wh il e filling thesystem. Thi s wo ul d give th e air a chance toescape as the system filled up with coo lant.Although we are not aware of aspirin caus in g anyproblems currently, with new coolant addit ives,radiator sea ls and gasket materials all sorts ofreactions may take place. Mercedes-Benz coo l-ing systems have the expansion tank at t hehighest point, so are self-b leed ing. StarTuned 15
  12. 12. COOLING SYSTEM SERVICE These days with dual heater cores, auxi liary cooling pump motors and externa l cool ing If You Want To Pull Out system plumbing, there is a mu lt itude of places The Big Guns air can get trapped . This can lead to symptoms Another too l investment that will save you such as overheating and poor heater perform- t ime, ensure all of the coo lant is being ance . You may have to run the engine for a exchanged and reduce air in the system, there whi le before you bleed al l the air out. Check are coo lant exchange machines . These no longer the service procedures and see if there is a require that you put the vehic le on a lift and bleed procedure for the particular veh icle yo u open dra in plugs on the radiator and engine are working on. block. As long as you have access to a coolant There are tools avai lable to assist you in the hose, you can exchange the old coolant with a refill procedure. You have probably heard of "vac- fresh supply with a minimum of mess.uum assist" cool ing system fillers. These too ls These mach ines have externa l tanks you canuse your shops compressed air supply and a pre-fi ll with yo ur 50/50 disti ll ed water andvacuum pump to generate a vacuum in the coo l- antifreeze coo lant mix. The next step is toing system . Once the system is in a vacuum, a disconnect the upper radiator hose and connectval ve allows coolant from a pickup tube to fil l t he the coo lant line adaptors from the machine tovacuum in the coolant passages. This can reduce the car. Most coo lant exchange machines do notand/or eliminate any air bound in the coo li ng need the vehicle to be warmed up, or evensystem . There is no need to run the veh ic le for running. A vacuum pump pumps out the old fluidan extended period of t ime to self-bleed the air into an empty tank and replaces it with theout of the system . You can now move on to yo ur coo lant prepared in the refill tank. You shou ldnext job. know by now the type of anti-corrosion/ anti- If you wou ld like to comp lete the task of drain- freeze we sho ul d be using in Mercedes-Benzing the coo ling system, you can flush out the vehicles, but th is is on ly half the equation .heater core. Removing contaminants wil l improveheater function and prevent further blockages Water Qualitydown the road. The great part here is the time In th is article, we discussed proper coolingsaved. Most Mercedes-Benz vehicles use an aux- system service procedures, anti-corrosion anti-iliary coo lin g pump motor. Th is motor can be freeze and too ls to test and exchange theactivated through the use of your Compact III coo lant. One more subject we need to discuss isscan too l, or by just supplying power and ground something we very often take for granted. Th at isto the pump motor directly. The motors draw water supp ly. "C ity" water for drinking is treated.only about .5 amps and wi ll pump all of the It contains fluoride or ch loride salts due to thecoolant out of the heater core wh ile you are treatment, so it is not desirable to mix it withrefilling it with new coolant. Most pumps are on coo lant. Do not use this, or hard water, inthe output side of the cooling system. Mercedes-Benz coo ling systems. In the oddDisconnect the line on the pump returning the chance you have a supply of spring water, eithercoolant t o the water pump and run it into a con- bottled or from a wel l, do not use this, either.ta iner. Block the water pump side of the line you Bottled water is not regulated and probab ly have just disconnected and run the pump until contains minera ls that can react with engine you see new coo lant. We wou ld not recommend components, and also acts as an abrasive when using any aftermarket coolant flushing solutions passing through the coo lin g system . Instead, as these may conta in ha rsh chem icals that can use disti lled water. It is the best to use since it attack seals and gaskets after a few thousand conta ins no additives. Th e slight additional cost miles. If the cooling system is maintained in a of disti ll ed water shou ld not significantly increase timely manner these "coo ling system repairs in the cost of the overal l coo ling system service a can" should not be necessary. and eli mi nates harmfu l contaminants.1 S 6 tarTuned
  13. 13. + Distilled WaterHere is a tool that might be a In Conclusiongood investment providing you sell Cooling system service is one of the simplerenough cooling system services. tasks you perform for your customers, but it is also one of the most important. AdvancementsYou can keep one tonk with a in the chemical composition of coolants and50/50 mixture of Mercedes-Benz cooling system plumbing make corrosion and air-bound systems real problems that need to becoolant and distilled water and addressed . Using Mercedes-Benz antifreeze willexchange it with the old coolant in sure corrosion protection and warranty claims will not be an issue . Draining the block, radi atorwithout even running the engine. and heater core will insure all expired coolant isYou may still have to pump out removed . Finally, refilling the system without air pockets can be accomplished with a vacuum-the heater cores separately. assist tool, or a coolant exchanger. If customers notice your attention to detail on the cooling system, we are sure they will trust your judgment when it comes to more involved repairs, and that is good for all. StarTuned 17
  14. 14. Replace - We replace more parts than aftermarket brands.Engineered - Designed to meet original OEM drawings.Manufactured - Made with same OE components as factory parts.Assembled - Completely assembled from components and not just repaired.N - Tested to new unit standards. ew Improved Technician Efficiency
  15. 15. 260E 1987-1989 300CE 1988-1993 300EITE 1986-1993 300SE/ SEL 1988-1991 300SL 1990-1993 MODELSA 0002300511 80 350S0 1991 C240/C320/S430 3SOS0L 1990-1991 AOOO 230 9111 80 S500/CL500/CLK320 2004 E320 1994-1995 SL320 1994-1997 E320/E500 2003·2006 SL600 1996·1997 A001 2301211 80 CLSSOO 2006" 400E/SOOE 1992·1993 500SL 1990·1993 ML350lML500lML55AMG 2003"A 0002300611 80 E420 1994-1995 A001 23028 11 80 E500 1994 G500/G55 (NOT G55K) 2003+ SLSOO 1994-1999 A001 230 68 11 80 ML320/ML430 UPT02000 1900 1986·1989 1900T/3000TI TOT 1987 S55AMG/CL55AMG 2003·2005 190E 1985·1993 AOOO 230 90 11 80 C240/C320 UP TO 2003 260E 1987·1989 300CE 1988·1989 CLK320 2003A 000 2301111 80 3000 1987·1993 300E 1986-1992 AOOO 230 781180 C32AMG KOMPRESSOR 2002·2004 300SE 1988·1992 300SEU TE 1988·1991 AOOO 230 97 11 80 2004 E3000 1995 C2201C280 1994-1995 S600/CL600 2001+A 000230 1311 80 C36 AMG 1995 A001 230 0111 80 S6SAMG/CL65AMG 2005+ 300S0 1992·1993 E55AMG 2004-2006 300SE/600SEC 1993 600SEL 1992·1993 CLSSSAMG 2006A 000 230 17 11 80 S3201 S3500 1994-1995 S420 1997·1999 A001 230 1411 80 E350/ESSO 2007 S600 1994-1996 CLS550 2007 CL600 1998-1999 S320 1995-1999 E320CDI 2005-2006A 000230 2211 80 S3500 1995 CLK550 2007 S600 1996·1999 CLK55AMG 2003" 1900 1986-1989 A001 2301911 80 1900T/30001 OTI TOT 1987 SLKS5AMG 200S... 190E 1985·1993 260E 1987·1989 CSSAMG 200S"A 000 230 2411 80 300CE 1988·1989 300E 1986·1992 2004 300SE 1988-1992 300S0L 1986·1987 300SEUTE 1988·1991 420SEU 560SECI SEL 1986·1991A 000 2302511 80 560SL 1986-1989 400SE 1992 400SEU 500SEC 1993A 119 23000 11 80 500SEL 1992-1993 S420/500 1994-1995 C280/C43 AMG 1998-2000 CLK320 1998-2003 CLK430 199~2003 CLK55 AMG/ML320 2001-2002A 000 2307011 80 E320 1998-2002 E430/E55 AMG 200G-2002 ML430 199~2001 ML55AMG 2000 SLK230/SLK320 2001 - 2004 CL500 2001-2003 CL55 AMG 2001-2002A 001 23002 11 80 2002-2003
  16. 16. FEATURE ARTICLE aseaml s transfer of engine to the road.To add to the experience adaptive transmission shiftingtailors the vehicle to the driver. Lets see howMercedes-Benz manages these two feats. How do we isolate a drivabi lity issue from a The job wi ll remain profitab le if the first step is intransmiss ion shifting issue? Th is may sound the right direction. In the case of a drivabil itysimple, but a bucking sensation may fee l li ke a prob lem/transm ission shift issue, you need tomisfire when it is actually a transm ission va lve determ ine if it is one or the other because therebody control valve com ing in and out. Even if we are two different should give the technic ian andetermine that it is a transmission problem, how idea on what might be wrong and where to look .do we isolate if the problem is with the mechan i- Try different driving patterns, such as differentcal part of the transmission or the computerized rates of acceleration. Also, try manually shiftingelectronic controls? Proper testing methods have the automatic transmiss ion . You can try holdingnever been as critical as they are today. The the transm ission in a fixed gear and see if youexpense of an improper diagnosis lead ing to an can duplicate the problem. Remember, theimpro per repa ir can leave the customer with a transm ission contro l unit wi ll limit the rpmbad taste in his or her mouth. You need to be of the engine.sure of your test methods and know how to eva l- Another form of testing is to observe how theuate the ir results. Self-diagnostic features incor- system functions and see if we f ind anythingporated in contro l units today have helped in the wrong, either electronica ll y or mechanically.battle with complexity. Th is coupled with proper We can also make a change to the system,training and information should leave you capa- either electrica l or mechanical, and see howble of isolating the problem and performing the the veh icle reacts.pertinent repair. Observing inputs and outputs can be time- consuming on comp lex systems. This fac t is whatIn The Beginning made scan tools so prevalent. With a scan tool you can obse rve computer controls easily. The first step in any diagnostic process is However, th is is processed data and its relativelyarguably the most critica l. Going off in the wrong slow depend ing on the nature of the problem.direction can waste an incredible amount of time Processed computer data is not real-time, likethat you will more than likely not get paid for. what you see on an oscilloscope. It is entirely20 StarTuned
  17. 17. ATF Th e next major step is to check the fluid level. On later model Mercedes-Benz vehic les, thi s is not a simple as it sounds. You wi ll find the fill tube, but you will probably not find a dipstick. The dipstick is now a tool to be kept by your tool- box. In add ition to having the tool at your dispos- al, you also need to have the transmission at a spec ific temperature. Too hot or too cold may not give an accurate reading. The fluid levelYou will need to have this tool at shou ld be checked at 25 deg. C (77 deg. F.), and it should read between the "Max" and "Min"your disposal if you are going to marks on the dipstick tool. Allow the engine toservice Mercedes-Benz vehicles. warm up about 2 minutes and bring the trans- mission temperature up to about 80 deg C (176The vehicle has no dipstick so you deg F) and the level should still be betweenneed to provide your own. Measure "Max" and "Min" on the stick. The transmission needs to be in a drive gear, so make sure thethe ~uid level in a drive gear with parking brake is on and have a second techni-the temperature of the ~uid first at cian in the veh icle applying the brakes. If repair work has been carried out have the technician25 deg C and then at 80 deg C. move the selector lever into each gear a few times to evenly distribute fluid throughout thepossible for an input or output to misbehave and transmission.the comp uters self-diagnostic system never Of course, there are always debates on whatpicks it up . A scan tool is a good way to get type of transmission fluid to use. In the case ofstarted when monitoring the computers contro l Mercedes-Benz, use only the exact ATF recom-of the system, but it shou ld always be followed mended in the service literature or owners by testing the system visua ll y and with direct manual, wh ich you can be sure is of the proper electrical testing. viscosity and conta ins the necessary friction StarTuned 21
  18. 18. TRANSMISSION MAINTENANCE misfire . While driving, you may want to look at the misfire co unter t hrough your SDS. If you do not see any misfires, then you are probably dea ling with another problem . Th is is an example of observa nt testing. Another type of testing is "intrusive" testing. Here, you make a change to the system and see how the vehicle reacts. To see if a transmission solenoid is toggling, you simply need to unplug the main connector and t he trans mi ssion . Th is connector, very often, ca rries t he power, ground, or both to the trans- mission shift and pressure control solenoids. By unplugging it, we are forcing the transm ission into its "fa il-safe" program. For example, if the unit is stuck in a parti cu lar gear, eliminating electronica lly-contro ll ed sh ifting isolates the mechanical transmission from its electronic control. If the problem persists, you have two choices.Transmission ~uid ~ushing can Either look in other areas such as the engine, orextend the useful service life of the the problem is in the mechanical function of the tra nsm ission. With the transmission in "fail-safe"transmission. It can remove ~uid yo u must be carefu l of engine rpm, and exces-that has been over-heated and is sive road-testing can actua lly damage the transmission. Thi s type of testing should on lyfull of clutch material. It cannot be applied if the se lf-diagnostic system andmake up for worn clutch discs, so scan data are not giving an ind ication of what is wrong.make sure the customer is aware If the problem is el iminated by unplugging theof the limitations. solenoid connecto r, plug it back in , watch the control of these solenoids and monitor the inputmodifiers. You may have read on the in ternet data to see if either is caus in g the symptom.that any synthetic transmission fluid may be With older transmissions, monitoring the lineused with no adverse affects, but those that have pressures and so len oid operation was not verynot been tested by Mercedes-Benz will vo id any difficult. With newer, smoother-sh ifting transmis-warranty on the unit, and may not provide the sions, however, this can be more cha llenging.necessary fil l-for-life protection the facto ry f lu id Thi s type of testing may not work in every case,offers . Th is is imperative on t he later model but it should apply in most. Mercedes-Benz vehi-72 2.9 seven-speed transmission. The Mercedes- cles are very good at self-d iagnosis, and veryBenz part# A001 989 45 03 is developed spec ifi- often a code is stored ind icating wh ere the prob-cally for this transm ission. Its higher friction lem may lie. Howeve r, if we do not have a codeconsistency and therma l stability is required and to work with , we still have a starting po int.it shou ld not be mixed with another type of fluidduring a service. The Mercedes WayBack To Our Problem How wou ld a transmission control unit tell if the qua lity of the sh ift is less than perfect? It Evalu ating an unusua l symptom like a light cou ld monitor t he current draw of the shift sole-bucking with steady throttle, you may think no id, but that would on ly inform you of shifting22 StarTuned
  19. 19. - !QI Vehicle [211.065 Control unit [Erc VehicleRead out fau n memory of transmission control unit and process stored fault Ic urrent ETC Ac t va I va I ves 1/3codes. ~ .6 ~------------ IFiltersta! Planet . speed sensor n2 ~~~._~_ .. . . rpm ,. VG-Tron. 02 Planet. speed sensor n3 ~~~._._ ... _ rpm III ME2-SFI . 31 Turbine speed Quick teot IIIE r pm 03 iilual/deSiredliiar 0S Low range program ON/s. ~trMost of the time Mercedes-Benz Looking at scan data, you cancomputers are capable of determin- sometimes find large problems withing a problem with their self-diagnos- sensors, providing they lost longtic system. Here, a few codes have enough for the computer to pick up.set on this 2 I I chassis, and two of In this case, the rpm sensor #3 isthem are related to the some foiled no longer supplying a signal. Yousensor: #3 rpm speed sensor. This should bock up this conclusion withsensor should now be tested directly electrical testing of the sensor. Lookto make sure the problem is not a at both the resistance and the ACwtrlng Issue. voltage signal.problems where the electronic controls created tells you the transmission shaft speed sensorsthe problem. If the problem is mechanical, the function is critical to the operation of the trans-control unit would need another way to tell if mission electronic control. You need to verify thatthere is a problem . Incorporated into the trans- these signals are working properly before you canmission are input and output shaft speed sen- start condemning other components.sors. On the later model 722 transmission, three Mercedes-Benz engineers provided additionalspeed sen sors are used. The first picks up the monitors for components related to shifting. Youturbine shaft speed, the second picks up the can evaluate a shift by monitoring action of thespeed of the planetary gearset, and the output fluid. By watching how long it takes to fully applyshaft speed sensor does just that - reads output the clutch pack and how much pressure isshaft speed. required to engage it, you can find out if the By monitoring these speed sensors, along with clutch packs are healthy. If excessive time andthe actual sh ift point, the transmission control unit pressure are needed to provide grip for thecan see if the proper relationship is maintained clutches, they are probably worn. The SDS toolbetween th e two.. If the input shaft indicates a allows you to access this data for each clutchhigher speed than the output shaft speed sensor pack. This is extremely helpful when you find(for a given gear ratio) then the engine rpm must shifting problems only in particular gears.have flared as the transmission slipped into the In the later model Mercedes-Benz transmis-next gear. This can be accomplished even if the sions, there can be up to seven forward gearproblem is not severe enough for the driver to ratios . You will have individual forward gears andnotice. To monitor these signals directly is difficult torque converter lockup for each gear. The oper-even with an experienced lab scope user. This also ating pressure is controlled by a pressure control StarTuned 23
  20. 20. TRANSM ISSIO N MAIN TEN ANCE ••• Vehic le Vehicle 1211.022 Control Lnit II:TC(Current ETC Ac t va I va I ves 113= .6jFilterstiJI Planet . speed sensor n2 f--- - - - - - - !Adaptation data VG -Tr . ~ 02 _ Planet . l1li r pm .~~iII!I speed sensor n 3 1I/I . BIiI _ rpm ~~~._~_. ME2-Sf l . 31 Tu r bine speed Quick test II!IiII rpm 0 3 iIIvaltdesiredliiar 05 Low r ang e pr ogr am ONtS. ~Vt Notice how you are given the maximum and minimum limitsUsing the 50S, you can select for each reading, followed by theTransmission Adaptations" and view actual reading. You are olso giventhe readings. These will indicate the {til the reading at three temperatures.time for each clutch or brake, as well A higher (positive) number indi-as the {til pressure. By viewing the cates that more time and pressurenumbers you can determine if the is required to engage the clutch,transmission needs to come apart. which implies that the transmission IS worn.solenoid. In addition to the primary pressurecontro l so lenoid, each shift soleno id has its own Service Workpressure control solenoid. This allows for quickerand smoother sh ifts. If any of these solenoids If one of the solenoids or speed sensors needswere to stick, it would contribute to an improper to be replaced, it will probably be serviced as ashift. Let us look at an example of this data that unit. On many later mode l Mercedes-Benz t rans-we can use to test the solenoids . The first line of missions, all of the solenoids and sensors aredata is the "Fi ll Time of Clutch XX," with the incorporated into a plastic housing usua lly mount-letter designation of t he clutch you are looking ed on top of the va lve body. Whi le this mayat. For ease of interpretation, you are given the increase the overal l cost of a component replace-high and low limits of the shift monitor counter. ment, it does provide for ease of service . Typically, The next line you is either the "Brake or Clutch transmission service work is farmed out to a rel i-Fill ing Pressure" in mil libars. This informs us of able transmission rebuilder. A properly trainedthe pressure required to apply the clutch . If either technician can, however, dra in and remove theexcessive time or excessive pressure is required pan, remove the valve body (being ca reful tofor engagement, the clutch is worn or pressure is watch the seals) and replace the solenoid/sensor inadequate to comp lete the engagement. To plate. In the case of the 722 transm ission, thefurther assess th e problem, you can also reset transmission control unit is incorporated into the the adaptations. This "zeros" out the adaptations solenoid/sensor plate. Superior Mercedes-Benz and gives you a new starting point. A road test engineering should make this a rare fa ilure with that runs the ve hicle through all of its gears wi ll proper maintenance. There are also some other allow the adaptations to take place so you can key service procedures for the 722 transmission . re-evaluate the shift data. This is very useful The housing is magnesium so aluminum bolts are information when trying to determine if a replace- used . Th ey must be replaced when removed, then ment transmission is in th is vehic les near future. torque according to specs.24 StarTuned
  21. 21. A Mercedes-Benz should be true to its origins. So Mer cedes-Benz Classic Center When you want authentic parts, only the source will do. M"UC".IIOO~J To speak with our Parts Experts, call our Parts Order Desk at 1-866-MB-CLASSIC (1-866-622-5277) . Mercedes-Benz Classic Center USA, 9 Whatney, Irvine, CA 92618Call or visit for additional details and a copy of the limited Parts Warranty. © 200a Mercedes-Benz USA, LLC
  22. 22. Cushioning the BlowIn the last issue of StarTuned we introduced basic air bagmaintenance and repair and as promised, here is part two ofCushioning the Blow. Now well take a look at the EmergencyTensioning Device (ETD), further testing and checklists.26 StarTuned
  23. 23. Mercedes-Benz has always been at the ETD. The first stage uses an electric motor toforefront of occupancy safety. In 1969, United pretension the seat belt in order to secure theStates Federal law mandated automatic individual in the seat. This is often in response tooccupant restraint systems. Yet, since 1967 a signal from the BAS control unit (Or ASR/ESPMercedes-Benz had been developing airbag unit) in the event of a panic stop. The secondtechnology for its passenger vehicles. By 1980, stage uses a pyrotechnic ignition squib to fire athe company had started to employ this charge to tighten the belt even further if theresadvanced technology on a growing number of its an impact. There are also force limiters to slowlyvehicles. Initially, there were some of the same slacken the belts during certain accidents.concern s that we hear about today, such as how As mentioned earlier all you have to do toto prevent secondary injury as a result of airbag test the system once components have beendeploym ent, particularly as relating to children replaced is simply turn on the ignition key. Everyand smaller passengers. time you cycle the key, the SRS does a compre- Supplemental Restraint Systems (SRS) hensive self-test during the four to 20 secondshave come a long way since the early that the airbag warning light is on . There is nogenerations. Complex computer algorithms need to evaluate the system once this self-checkdifferenti ate between smaller and larger impacts, has passed. There may be codes in the system,seat occupancy detection sensors prevent airbag but these are past problems or at least problemsdeployment if a light-weight individual (child) is that are not occurring at this time. We recom-sitting in that seat, and dual/multiple-stage mend clearing all codes in the SRS after repairsairbags have been only a few of the advance- have been completed. This will help the nextments made over the years. technician working on the system to properly diagnose the current problem without any wasted effort.Emergency Tensioning Device Of course, some other critical components in the SRS are the acceleration sensors, otherwiseAnother component that needs to be replaced known as crash sensors. These are placed in in the event of an accident is the Emergency strategic locations throughout the vehicle to help Tensioning Device (ETD). The ETD is a pyrotech- determine the point of impact and the severity of nic component that retracts the seatbelts during the crash. The SRS control unit also has an impact to keep the occupant in the proper posi- acceleration sensor built into it and it is oftention for contact with the airbag and distribute mounted on the transmission tunnel between the some of the pressure exerted on the occupants drivers and passengers seats. This sensor read-body more evenly. The ETD is commanded to ing, in combination with the satellite sensorsdeploy by the SRS control unit when an impact is placed around the body, help the SRS controlsensed. If the impact is not severe, the SRS con- unit learn the facts about the direction and leveltrol unit can activate the ETD without the airbags of impact of the collision. The control unit alsoin only th e seats that are occupied. Both front houses a roll-over sensor that determines thatseats have this feature and some rear passenger conditions exist for an impending roll-over. All ofseats closest to the doors. The SRS control unit these sensors help the computer logic decideuses the Seat Belt Buckle switch to determine what airbags need to be deployed and when.what seats are occupied . These switches can be For instance, in the event of a side impact thethe source of a self-diagnostic code and can be side or curtain airbags would be deployed. Themonitored on you factory scan tool. SRS control unit also receives signals from other Most Mercedes-Benz vehicles utilize a dual-stage control units on the network, such as the BAS, to StarTuned 27
  24. 24. COLLISION REPAIR / AIR BAGS PART IIWith a paid subscription to www.startekinfo.com. you can access information such ascomponent location of the drivers seat ETD found mounted here in the B pillar. These unitshave a pyrotechnic charge that fires and applies tension to the belt even if the airbags donot deploy.indicate a panic stop, and if the ETR needs to be key in the off position. Also, identify if the vehic ledeployed in either the first or second stage has the Dual Battery system, and, if so, discon-before impact. nect the other one as we ll. Then, unplug the component you would like to test and insta ll a jumper plug of a fixed resistance between theA Short Checklist two pins of the component, such as the driversWhen it comes to diagnosing a problem in the side airbag squib, the passenger side ETR squib,SRS, you wil l find no better tool than the SRS or the front acceleration sensor. Measure thecontrol unit itself. As mentioned earlier, if it resistance of the circuit with your DMM . Ofdetects a problem in the system it will flag a course, this testing cannot be performed withcode for the components in question. Testing is the airbags connected to the system as thererelegated to measuring circuit integrity between may be an accidental deployment of an airbag.the SRS control unit and each of its inputs and Resistance should read the same as when yououtputs. Be sure to only unplug the SRS control installed the jumper, although a few tenths of anunit with the battery disconnected, or the ignition ohm higher is acceptable to account for the28 StarTuned
  25. 25. Enticingly graceful and dynamic. Strong support, too. QUALITY FIT PERFORMANCE VALUE SERVICE WARRANTY Ellery part comes with the reassurance oj a strong 12-month/unlimited-mileage limited warranty- with additional aJllemge }or engines and transmissions: Unlike any other.The part is just part of the story. The precise fit and superior performance of a Genuine Mercedes-BenzPart is a given. But equally important is that each Genuine Mercedes-Benz Part - down to the last nut,bolt and gasket - comes with the unmatched technical support and expertise from your dealer andMercedes-Benz. All evidence of our constant dedication to supporting your business in more and betterways than anyone else. And thats the best part. Visit mbwholesaleparts.com or contact your dealer. Mercedes-BenzSee your Merr:etles·8enz dealer for details and a copy Of the Merr:etles·8enz ((eplacement Parts Limited Warmnt)(
  26. 26. COLLI SIO N REPAIR / AIR BAGS P RT II A additiona l labor involved in removing and reinstalling components to access the problem. This wasted time is probably coming out of your bottom lin e on the job. The Importance of a Proper Repair In the course of a body repair job, there may be the temptation to cut costs by using aftermar- ket, or even used parts. These parts have already been involved in some incident that sent the veh icle to a sa lvage yard in the first place and have been sitting there exposed to the elements. This often leads to corrosion . These conditions can wreak havoc on internal circuitry and result in unpredictable operation . It could be a liabilityThis is a drivers door airbag on an ML series. nightmare if corners were cut that provide less- than-adequate SRS operation if another accidentNotice how the unit is riveted in to provide occurs. This may also put you in hot water withclearance for the window, so nuts and bolts the in surance company that is footing the bill forshould not be used as a substitute. the repair. The company will often guarantee the work it has insured, and may force you to absorbwiring in the syste m. If the resistance is the cost of substandard components and work-abnormal ly high, it indicates an open circuit or manship. So, it makes sense to use only genuinepoor connection somewhere in the wiring. If the Mercedes-Benz replacement parts available fromtest value is lower than the resistance of the the parts department of your authorizedjumper, there is a short between the two wires Mercedes-Benz dea ler.you are testing. If the resistance it acceptable,yet you still flag a code, you are probably dealingwith component failure. Depending on the location of the harnessbeing tested, you may have to replace the who le harness or find the damaged wiring in the exist-ing harness and repair it. In the case of theacceleration sensor, one wire comes from theSRS control unit and the other wire continues toa grounding point. You will need to test resist-ance between the single wire on the SRS contro l unit and ground to determine if the wiring is the problem, or that there is a failed component. With all the SRS components installed in the vehicle and everything else safe to connect the battery, you can turn on the key and verify that the SRS/ Airbag li ght goes out. If not, you can retrieve codes and start testing the necessary circuit in the system while the car is sti ll apart and repairs can be performed. If you wait until the entire veh icle is assembled, there may be30 StarTuned
  27. 27. STARTUNEDGENUINE MERCEDES-BENZ PARTS .. , NEARBY Belmont Palo Alto Walnut CreekAlabama Pa rk Avenue Motors Mercedes-Benz of Wa lnut Creek Autobahn Motors 650-637-2333 650-494-0311 925-937-1655DothanMike Schmitz Automotive Beverly Hills Pasadena West Covina334-794-6716 Mercedes-Benz of Beverly Hills Rusnak/ Arcadia Mercedes-Benz of West Covina 310-659-2980 626-795-8004 626-859-1200Hoover Buena Park PleasantonCrown Automobile Colorado House of Imports Mercedes-Benz of Pleasanton205-985-4200 714-562-1100 925-463-2525 Colorado SpringsHuntsville Calabasas Riverside Mercedes-Benz of Colorado SpringsMercedes-Benz of Huntsville Mercedes-Benz of Calabasas Wa lters Auto Sales & Service, Inc. 719-575-7950256-837-5752 818-591-2377 951-688-3332 Denver Carlsbad Rocklin Murray Motor ImportsMobile Von Hausen s MotorsMcConnell Automotive Hoehn Motors 303-759-3400 760-438-4454 916-630-8877251-476-4141 Chico Sacramento LittletonMontgomery Courtesy Motors Auto Center Mercedes-Benz of Sacramento Mercedes-Benz of LittletonJack Ingram Motors 530-893-1300 916-924-8000 303-738-7700334-277-5700 EI Dorado Hills San Diego Westminster Mercedes-Benz of Eldorado Hills Mercedes-Benz of San Diego Mercedes-Benz of WestminsterTuscaloosa 916-567-5100 858-279-7202Leigh Automotive 303-410-7800205-556-1111 Encino San Francisco Mercedes-Benz of Encino Mercedes-Benz of San Francisco ConnecticutAlaska 818-788-0234 415-673-2000 San Jose DanburyAnchorage Escondido Mercedes-Benz of DanburyMercedes-Benz of Anchorage Mercedes-Benz of Escondido Beshoff Motorcars 408-239-2300 203-778-6333907-277-3383 760-745-5000Fairbanks Fremont San Jose FairfieldAuto Service Company Fletcher Jones Motor Cars Smythe European Mercedes-Benz of Fairfield907-456-621 7 510-623-1111 408-983-5200 203-368-6725Arizona Fresno San Luis Obispo Greenwich Mercedes-Benz of Fresno Kimba ll Motor Mercedes-Benz of GreenwichChandler 559-438-0300 805-543-5752 203-869-2850Mercedes-Benz of Chandler San Rafael Glendale Hartford480-403-3400 R.A.B. Motors Calstar Motors New Country Motor CarsPhoenix 818-246-1800 415-454-0582 860-278-2000Phoenix Motor Santa Barbara602-264-479 1 Laguna Niguel Mercedes-Benz of Laguna Niguel Santa Barbara Auto Group New London 949-347-3700 805-682-2000 Carriage House of New LondonPhoenix 860-447-3361Schumacher E uropean Santa Clarita480-991-115 5 La Jolla Heinz Gietz Autohaus Mercedes-Benz of Valencia North HavenTucson 858-454-7137 661-753-5555 Mercedes-Benz of North HavenMercedes-Benz of Tucson 203-239-1313 Los Angeles Santa Monica520-886-1311 w. 1. Simonson Downtown L.A. Motors Delaware 213-748-8951 310-526-4700Arkansas Santa Rosa Milford Manhattan BeachFayetteville Carwell Smothers European I.G. BurtonMercedes-Benz of Northwest Arkansas 310-303-3500 707-542-4810 302-424-3042479-521-7281 Modesto Signal Hill Wilmington Modesto European Mercedes-Benz of Long Beach Mercedes-Benz of WilmingtonLittle Rock 209-522-8100Riverside Motors 562-988-8300 302-995-2211501-666-945 7 Monterey Stockton Mercedes-Benz of Monterey Berberian European Motors FloridaCalifornia 831 -375-2456 209-944-5511 ClearwaterAnaheim Newport Beach Thousand Oaks Lokey MotorMercedes-Benz of Anaheim Fletcher Jones Motor Cars Silver Star A.G. 727-530-1661714-777-1900 949-718-3000 805-371 -5400 Oakland Coral GablesArcadia Torrance Mercedes-Benz of Oakland Mercedes-Benz of South Bay Mercedes-Benz of Cora l GablesRusnak/ Arcadia 305-445-8593626-447-1117 510-832-6030 310-534-3333Bakersfield Palm Springs Van Nuys Cutler BayMercedes-Benz of Bakersfield Mercedes-Benz of Palm Springs Keyes European Mercedes-Benz of Cutler Bay661-836-373 7 760-328-6525 818-461 -3900 305-251-0345 StarTu ned 3 1

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