Star tuned magazine december 2008


Published on

Published in: Sports, Technology
  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Star tuned magazine december 2008

  1. 1. TO OUR READERS IN THI S ISSUEWelcome to StarTuned, th emagazi ne for independent se rvice 4 EYE ON EMISSIONStechnicians work ing on Mercedes- Automobile emissions are a hot topic amongBenz ve hicles. Your Mercedes-Benz environmentalists, drivers and tech nic ia sponsors StarTuned and Mercedes-Benz vehicles utilize emissionsprovides the information co ming systems, such as Exhaust Gas Recircu latio n,your way in each issue. to reduce harmful pollutants.Merc edes-Be nz wants to present th einformation you need to know todiagnose and repa ir Mercedes-Benz 10 CAN WE GET ON THE BUS?cars accurately, qui ck ly and the first Since the early 90s, Mercedes-Be nz has developedti me; text, graph ics, on-lin e and oth er its Controller Area Network (CAN) to control howtechn ica l sou rces comb ine to make components communicate with each other and with usth is poss ible. through our Compact III or Basic. How ha s this evolved ,Feature articles, derived from and wha t does it mean to diagnosis and repai r?approved compa ny sou rces, foc uson be ing usefu l and inte resting.Ou r digest of techn ica l informati on 16 CONTROL UNITScan help you so lve unanticipa ted GO BACK TO SCHOOLproblems qu ick ly and expe rtl y.Our list of Mercedes-Benz dea lers Installing a new control unit to replace the fai led one iscan help you f ind Genu in e only half the job . With various combinations of optionsMercedes-Benz Parts. available on the same model, the new unit has to learnWe wa nt StarTuned to be both which are installed and how to work with the m..helpfu l and informative , so please letus know just what kinds of features 26 TAKING STOCK IN BONDSand other diagnostic services yo ud (CHEMICAL BONDS, THAT IS)like to see in it. We ll continue to Ease of manufacture, shear strength and aesthetic bodybring yo u se lected service bull eti nsfrom Mercedes-Benz and articles lines are only some of the reasons Mercedes-Benz usescovering th e different syste ms on chemical bonding for joining body panels. How can wethese ve hicles . duplicate an OEM panel seam?Send you r suggesti ons, qu estionsor comme nts to us at:StarTuned 31 GENUINE MERCEDES-BENZOne Mercedes Drive PARTS ... NEARBYMontva le, New Jersey 0764 5 Wherever you are in the United States, theres a nearbyPh one: 1 800 22 5 6262, ext. 7112 so urce of genuine factory parts for your customerse-mail: Sta m Mercedes-Benz vehicles.StarTu ned is a quarterly publication of Mercedes-Benz USA, LLC (" M BUS A"). No par t 0 f th i s newsletter may be reprod uced with out the express wri tten permission ofMBUSA. Ed ito r i a I and Circulation Offices: 598 Pine Po int Dr ive, Ak ron, Ohio 44333. Caution: Veh icle servicing performed by untrained persons could re su i t i n s e ri 0 u sinjury to those perso ns or others Informati on cont ained in this newsle t ter is intended for use by trained, professional a u to repair technic i ans ONLY. Thisinformat ion is prov i ded to inform these technicians of conditions which may occu r in some vehicles or to prov ide informat i on wh i ch cou l d assistthem in proper servicing of these veh icles . Properly tra ined technic ians have the equ ip ment, tools, safety instructions, and know-how to perform repairscorrect ly and safe ly. If a co nd it ion is described, DO NOT assume that a top ic covered in these pages automatica lly applies to yo ur vehic le or that your ve hicle hasth at cond ition. StarTun ed is a registered trademark of MBUSA.
  2. 2. STARTUNEDInformation for the Independent Mercedes-Benz Service ProfessionalDecember 2008 U.S. $6.00 € 1 2.50 Volume 8 N umber 4Group Publisher Contributing Editor MBUSA Technical Production ManagerChristopher M. Ayers, Jr. Chip Keen Content Advisor Devon Ayerscayers@ Donald Roto lo Donald.Rotolo@mbusa.comSenior Proj ect Director Contributing Editor Circulation ManagerTamra Ayers Kerry Jonsson MBUSA Project Manager Joann m Stephen Langelotti jturner@cmacom Stephen.Langelotti@mbusa .comEditorial Director Contributing Editor List ConsultantBob Freud enberger Tom Nash Art Director NFocusbfreud@ Jef Sturm jsturm@ :C--~~"""i8~ "" ~ ,.
  3. 3. Eye On Emissions,
  4. 4. P0400 And Beyond Take a deep breath and enjoy the fresh air. which cause the formation of NOx. It wasnt always this way. Since the 1960s, To counteract this, a small portion of the automakers have made tremendous previously-burned exhaust gas is introduced strides in reducing the air pollution their into the intake charge, diluting the charge vehicles produce, and Mercedes-Benz has and knocking the top off the peak always been in the forefront of this effort. temperatures, which cuts NOx. Hydrocarbons (HC), carbon monoxide (CO) _ _ _ When EGR is not working the way it was and oxides of nitrogen (NOx) make up the designed, NOx goes up and/or drivability terrible trio of gases that have been targeted. problems can occur. Three-way catalytic In this article, well look at what M- B has converters, of course, also reduce NOx, but done with EGR (Exhaust Gas Recirculation) here were dealing with the EGR system only. to reduce the last, and what you need to If there is insufficient EGR flow, NOx know to keep that system functioning. emissions will increase. Excessive EGR flow Computerized engine managem ent allows promotes inefficient co mbustion and for leaner air/fuel mixtures , which help keep misfiring. With OBD II, EGR systems are HC and CO down. But these leaner mixtures monitored for their performance through lead to higher combustion chamber tempera- a series of computer-controlled tests tures in the neighborhood of 2,500 deg. F., called monitors. Here is the layout of a late-model EGR system. The EGR valve is mounted on the cylinder head. The EGR solenoid is on the valve itself The EGR pipe feeds exhaust gases to the intake manifold. StarTuned 05
  5. 5. What Are The Symptoms? _ _ _ When an EGR system problem is present, the symptoms often feel like theyre caused by something else. Pinging can occur, which will lead to an increase in NOx production beyond what even a good catalytic converter can handle. Most Mercedes-Benz engines have knock sensors that inform the ME (Motor Electronics) control unit if the engine is detonating. The control unit then retards The EGR valve and solenoid are ignition timing, but performance will besold as one unit. The large reduced. If EGR flow is excessive, particularly at low rpm, it can displacethreaded opening is where the enough oxygen to cause misfiring. Thispipe that leads to the intake can lead to unstable id ling and hesitation. Most of the time, excessive EGR flow doesmanifold attaches. The liquid not have a significant effect on drivabilityinside is carbon cleaning solution. in the highway cruising range - the EGR is wide open at this point, depending on engine load. It is in the lower rpm ranges that the relatively small amount of EGR gas has a significant effect. EGR problems can feel like an excessively rich or lean condition, and misfiring can also cause you to mistrust the oxygen sensor signal voltages and fuel trim readings . _ _ _ On OBD II vehicles, an EGR monitor will test the integrity of the system . It is critical to understand how the ME control unit determines how the EGR system is functioning. This EGR monitor will deter- mine if an EGR code is going to set. The system also needs to determine if there is insufficient or excessive EGR flow. If you are using a generic protocol scan tool,The MAP sensor is only used to you may only see the EGR code P0400, indicating there is a general problem withdiagnose emissions-related systems the system . With Mercedes-Benz factory-such as EGR and EVAP fiow issues. specific software, you can often retrieve a more detailed account of a particular EGRYou can use the MAP to monitor failure. Either way, the Mercedes-Benz MEmanifold vacuum and the open the control unit is capable of determining if there is an EGR flow fault often b eforeEGR valve. Watching the change in there is any sort of a drivability issu e.the vacuum reading will tell aboutthe fio w of the EGR system.06 StarTuned
  6. 6. The First Steps• •_ As mentioned earlier, an EGR flow problem can fe el like an excessively rich or lean condition . Also, too mu ch flow has a more significant effect at idle than at cru ise, so test the vehic le at id le. Making the mixture leaner by creating a vac uum leak wil l temporari ly smooth out a rough idle if the mixture is too rich . By the same token, adding propa ne to a lean-running engine will temporarily smooth things out. If EGR gases are involved, combustion Blocl<this EGR passage to eliminate efficiency is reduced, not because of too the possibility of any exhaust making much or too little fuel, but because of too little oxyge n in the intake charge. EGR it into the intake manifold. If the gases have displaced some of the charge, engine runs smoother, you have a so adding fuel or air wi ll not correct t he mixture. Its the excessive dead (low leaking EGR valve. VerifY that it is not oxygen content) exhaust gases ki lling being opened by vacuum from a combustion, not incorrect fuel mixture . solenoid thats stuck. Creating a vacu um lea k (to correct a rich condition) or adding propane (correcting a lean condition) is a quick way we can prove we do not have a mixture problem . If spark and basic engine are tested and are satisfactory you should now start thin king about excessive EGR flow at the wrong ti me .• •_ Removing the EGR va lve and blocking off the passage is a way to definitively eliminate the possibility th at exhaust is affecting the mixture. If the idl e is better, you know the EGR is stuck open, or that vacuum is reach in g the va lve at the wrong time. Yo u can attempt to "un-stick" it, but repla cement is a more certain repair. If vacuum is bein g applied to the EGR valve at the wrong time , you need to find out why._ _ _ The EGR va lve should not be open at Here we are monitoring the ground idle with the vehic le stationary. Th e ME control of the solenoid. A reading of contro l unit needs to see veh icle speed before it allows recirculation . Th e contro l I 2 V means it is not energized and unit operates an EGR co ntrol so lenoid no vacuum will ~ow to the EGR often mounted to the va lve itse lf. In lower valve. When the ME grounds the solenoid, the EGR valve should open. StarTuned 07
  7. 7. EMISSIONS rpm ranges, the solenoid is gradually openedVehicle 1209.365 Control unit IME-SFI 2.8 by pUlse-width modulated, or duty cyc leIActuations contro l, of the solenoid. At highe r rpm, the Y32 (Air pump sWltchover valve) . M33 (electric air pump) ( @ . EURO 3 . EURO 4 • 04 ) solenoid is fully grounded and the EGR valveY62 (Fuel injectors) receives maximum vacuum and opens allM1616 (Throllie valVe actuator)M3 ( Fuel pump) the way. Monitor the ground control of theY58/1 (Purge control valve)Y58/4 (Activated charcoal canister shut-off va lve) ( @) so lenoid, and if it is being grounded eitherY31/1 (EGR vacuum transducer) the ground contro l wire of the EGR solenoidMixture adaptation is shorted to ground, or the MEElectric suction fan for engine or air cond ~ ioningFuel tank leak test ( @ ) -- is mistaken ly grounding the wire. If theI gn~ i o n circ u ~ shutoffT1 /x (i gn ~ion coil(s)) solenoid is not commanded to ground, butY2216 (variable intake manifold switchover valve) manifold vacuum is passing through the solenoid to the EGR valve, then the solenoid is stuck open and needs to be replaced. The so lenoid and EGR valve are usual ly sold as an assembly, so in either case they get replaced F11 together. Remember a stuck open EGR valve or EGR solenoid wi ll flow excessive exhaust at idle and cause the engine to stal l or runHaving a Compact III at your very roughly.disposal allows you to commandthe EGR solenoid open. This not only The Other Sidetests the computers ability to ground If flow is in sufficient, expect slight pinging,the solenoid, but also allows you a failed emissions inspection with high NOx, and/or a MIL (Malfunction Indicator Lamp) Ito test the EGR system while the indicating a code in the P0400 range. Therevehicle is in your bay. is usually no severe drivability symptom associated with low EGR flow. The first test to perform is to simply open the EGR valve at idl e and see how the engine reacts. Older engines with the EGR mounted on the exhaust manifold usually on ly flow enough When dealing with an insufficient ~ow EGR code such as P040 I or P200 I you need to have a method to test ~ow. As you can see here, the EGR pipe is almost clogged. The ME control unit can see this restriction and ~ag the code. Cleaning out the pipe will {Ix the problem.08 StarTu ned
  8. 8. exhaust to produce a rough idl e. Newer engin es If the vo ltage increase is too sma ll , flow is with EGR systems mounted on the cylinder head being restricted. You know the valve and wi ll f low enough to cause the engi ne to sta ll right so lenoid are working, but th e EGR passages away. It only takes 5 to 6 in. Hg to full y open t he (typically the pipe) must be blocked with valve. The valve should also hold vacuum for a carbon deposits. A typical MAP sensor reads few min utes. Chances are if the va lve is not 4.5 vo lts with the key on and th e engine off. holding vacuum it is not open ing in the first Once you start the engin e, vacuum brings the place an d you wi ll probab ly notice very little signa l vo ltage on t he MAP to just about 1.4 change in engin e performance. volt s. Hold the engine at 1,000 rpm (it wou ld• • • Th e next step is testing the so lenoid . The st all at idle) and energize the EGR so lenoid . solenoid receives ign ition-on power from the Th e engine should start to run roughl y imme- vehic les power distribution system. Th e ME diately. If not, thi s usually means the EGR control unit grounds the EGR so lenoid to al low so lenoid is stickin g closed and may flag a manifold vacuum into the EGR va lve. You can code for insufficient flow. Th e code sets in either gro und the so lenoid yo urse lf with a jumper the sma ll amou nt of time the so lenoid is com- wire, or if you have a Compact III, yo u can use manded open, but the ME does not see a the Activations Menu to actuate th e solenoid. change in MAP signa l vo ltage - it should rise Any resu lt less than a quickly sta ll ed engine to ju st about 3.0V while the EGR is ope n. indicates a low-flow issue. In orde r to pass the De-energizing the so lenoid shou ld return the EGR monitor for OBD II , you should eva luate th e engin e to a normal idle right away. Otherwise, EGR system the same way the ME control check for a so lenoid or va lve sticking open. unit monitors it. Coming To A Conclusion Testing the Flow Once the repair is comp leted on OBD II Since the early 1990s Mercedes-Benz veh icles ve hicles you have the choice of clearing the have migrated away from CIS fuel injection and code and running a specific drive cycle to run exclusively use LH or HFM mass airflow type the monitor tests, or driving th e ve hicle systems. Testing EGR flow by monitorin g the through multiple drive cyc les until th e EGR change in the mass airflow reading is very mon itor passes at least three times. If you difficult. Mercedes-Benz chose to use a MAP are going to run monitors, remember to sensor to monitor manifold vac uum not for fuel make sure the coo lant temp does not drop contro l, but for diagnostic purposes. Through the below 80 deg. C, and keep the ve hicle speed MAP signa l, the ME contro l unit ca n watch the below 60 mph to prevent getting kicked out change in vacuum when the EGR is opened. If it of t he monitor tests. Yo u can use your indicates 18 in. Hg at 1,000 rpm and the EGR is Compact III to see if the conditions are met opened, the manifold vacuum will drop. The to run the monitor. larger the drop in manifold vacuum, th e greater Select "Measures for initiating fault path the flow of EGR gases. If the MAP signal change test s," then "EGR Diagnosis" whi le in th e ME is insufficient, the ME co ntro l unit deduces that contro l unit and you wi ll see bar graphs the flow is insufficient also, and a code is set. indicating engine tempera tu re and rpm You can simulate this by monitoring the vo ltage cond itions that need to be met. Tip : Most of on t he MAP sensor at 1,000 rpm and grounding the time the EGR monitor is run while th e the EGR so lenoid. (Remembe r that when ve hicle and engine are under a steady and man ifold vacuum is low MAP signa l voltage is long deceleration. Man ifold vacuum is at its high, and as vacuum increases MAP signa l vo lt- highest, so it is easier fo r th e ME control age decreases.) You shou ld see the MAP vo ltage unit to determine EGR flow. By running the in crease over 1.5V as the manifold vacuum monitor wh ile driving, you ca n verify that decreases and the engin e runs rough. your repair has addressed the prob le m. • • •_ StarTuned 09
  10. 10. What is the purpose of advanced technology? some instances, the brake switch input goesWhat is t he downside? Nowhere are these ques- directly to the ABS/ ASR/BAS (Braking Assisttions mo re relevant than in the automotive indus- System)/ESP modules. If each control unit thattry. The purpose of technology is to improve the needed it had its own brake switch you woulddriving experience, safety, and fuel mileage, and need one for the brake lights, one for theto reduc e harmful pollutants. The downside is ABS/ ASR, one for the cruise control, etc. Butever more complex systems . When things are there are only two brake switch inputs . How isworking as designed, fine. But, as the saying the lighting control module informed to turn ongoes, "To err is human, to really foul things up the brake lights? The signals get on the CANtakes a computer." (Controller Area Network) bus. Comp uter-controlled systems have expandedtheir role in modern vehicles. This has allowedfor such advancements as Motor Electronics(ME), antilock braking systems (ABS), electronicaccelerator (EA) systems, and so on. The evolu-tion of these various systems led to their integra-tion. Coupling wheel speed inputs from ABS andthrottle position sensors from ME determineswheel sli p under acceleration, and this slippagecan be controlled by applying braking force to aparticular wheel and/or by limiting power bymeans of the EA. This integration results inAnti-Slip Regulation (ASR). Include in theequation computer-controlled suspension andyou have the Electronic Stability Program (ESP). In later years, this in tegration has expanded toinclude all computer-controlled systems. Bodycontrols need to talk to one another during cer-tain functions. On convertibles, for example, thedoor con t rol units need to be informed that the This is a wiring diagram of onetop is bei ng opened so it can lower the windowsslightly to eliminate interference with the top. By of the first Mercedes-Benz CANpulling on the door handle, the central locking systems, including control units forsystem also informs the door modules that thedoor is being opened so the windows can be the powertrain. The DIIKSS (N I13opened enough so that they dont rub againstthe door seal. ignition), LH-SFI (N31 I fuel injection), As well as talking with other body control units, CCIISC (N413 Cruise & Idle), TCMthese computers may have to talk to powertrainco ntro l units. We wouldnt want someone open- (N /51 / transmission) anding the convertible top while driving at 60 mph. Diagnostic Module (N59 OBD I) areThe ABS/ ASR control unit must pass on thevehicle speed to the body system control units to all communicating on this network.prevent unsafe operation. To save weight and wiring complexity, control ~ -:-units have been strategically placed throughoutthe ve hi cle. However, testing something as sim-ple as brake light failure has become complex . In Stal"Tuned I I
  11. 11. CONTROLLER AREA NETWORK software, through the use of a Compact III orThe Bosch bus Basic , is very good at iso lating communication problems. Thi s is due to the design of the CAN Separate computers need to communicate protocol through error hand ling, bit timing andwith one another to perform these integrated synchro nization.functions. In Mercedes-Benz veh icles, theco mputers communicate through a CAN. CAN ProtocolRobert Bosch developed this form of serialco mmunication starting as early as 83, and acommerc ial vers ion was ava il ab le in 86. Mercedes-Benz ve hicles can have multipleMercedes-Benz was there during the Controller Area Networks. For powertraindevelopment phase of the CAN protoco l. systems, these may include:Serial-type communication means messages (inour case, 11 bit or 29 bit) travel over a single • ME Motor El ectron icswire. Paralle l bus communication, on the oth er • ETC El ectronic Tran smission Contro lhand, means each bit needs its own wire to trav-el down from one processor to another, which • ESM El ectron ic Shifter Modulewould resu lt in a lot of extra wiring. Seri al com-munication is whats used in a network of PCs. • ESP Electronic Stabi lity Program Analog or digital inputs are processed by a • SAS Sem i Automatic Suspensioncontro l unit for its own use . The unit th en ge ner-ates bus communication through square onloff • CGW Centra l Gateway Modulesignals. If another contro l unit needs some or allof the information on the CAN line, it determines Mercedes-Benz CAN protocol is sent out on awhat information it needs and uses it for its ope r- two-wire twisted pair integrated into the wiringation and its output controls. This contro l unit harness . One wire carries the CAN High signalmay also have inputs it puts out on t he CAN for and the other carries the CAN Low signa l. Thethe use of other control units. All contro l units in CAN High signal starts off at .65 volt when it isany particular network can share information via at ground , and th e square waves rise to aboutth e CAN. 2.5V. The CAN Low signa l starts off communica- What if the CAN were to "go down" and not tion at 4.65V when high and 2.5V when low. Thetransmit information? The control units cou ld not two signa ls are identical in so far as squarecommunicate and needed information wou ld be waves are conce rn ed, except that one signa llost. Most functions requiring inputs from mu lt i- switches high (CAN High) and the other signalple cont rol units would not work. Thi s wou ld switches low (CAN Low). If you were to scopeinclude something as basic as startin g and run- both signals on a dual-trace lab scope, theyning the engine. Without the Drive Authorization would appear to mirror each other. If a conditionSystem (DAS) approving the ign ition key, the ME existed that interrupted either the CAN High orcontrol unit wi ll not all ow the veh icle to crank Low signa l, an emergency mode would take overand/ or nm. So, these networks must be kept up and the comp uter wou ld communicate over the and running fo r the vehicle to perform as the CAN line that is sti ll functioning and set fault Mercedes-Benz engineers designed it, with all of codes in each control unit on that particular its safety features and creature comforts. CAN. If both CAN H and CAN L lines are shorted We need to have a diagnostic plan for when con- to power or ground, commun ica tion wou ld be tro l unit communication is lost. We will need to lost among al l contro l units on that CAN. kn ow the pathway of CAN commun ication and The wirin g among all the control units is wired how to test these signa ls. What often surprises in parallel. This means each control unit receives automotive technicians is how simpl e these sys- the same CAN High and Low signal. In 1992 on tems are to diagnose. Mercedes-Benz SDS the 140 chassis, the CAN wires we re spliced12 StarTun ed
  12. 12. Locate the bridge connectors under the carpeting and interior molding, and you can test voltage signals. Unplug suspect control units and verify there is no corrosion from moisture, coffee, soda, etc. In this case, you can unplug the connector to isolate the ME control unit.together at each contro l unit. If you are going to sp lices are named "Z" spl ice packs. Also in 96test the CAN, you will need to get to a co ntro l on th e newer chassis, bridge co nnectors areunit on the engi ne CAN, otherwise known as used to lin k the CAN wirin g. This can prove help-CAN C. Th ere is a terminating resistor on this ful when diagnosing CAN commun icat ion prob-CAN lin e. If you we re to unplug the LH-S FI (fuel lems that are the res ult of problem wiring. Weinj ection), or the DI/KSS (Direct Igniti on) co ntrol ca n access the CAN directly at severa l differentunits and measure resistance between the two areas whe re these sp lice packs or co nnectorsCAN wire s at that con nector, you wou ld read are located . We often try to go to the eas iestapproxim ate ly 120 ohm s. When unplugging either point we can access.the CC/ ISC (Throttle Module), Transm ission Mercedes-Benz uses multiple CANs. The pow-Control Module (TCM), or the Di agnostic Module ertrain CAN is CAN C. Th e Body CAN is CAN B.and chec kin g resistance between the two CAN Th e diagnosis CAN is referred to as CAN D.wires, you sho uld read app roxim ate ly 60 ohm s. Th ere can also be a MOST bus, but th at is a fiber Remember, only one co ntrol unit at a time optic network that we will cover in anothe r arti-should be unplugged to perform this test. Th ese cle. When eva luating co mmunication problemscontro l units are difficult to scope for the CAN H betwee n contro l units, yo u shou ld find out whichand L signa ls sin ce the connector faces down ones are on that particular CAN, and, using yourand the sp lices are underneath the co ntrol units Compact III or Basic, try to commu nicate wit hin the hou sing. each control unit that is connected. You shou ld Starting around 96, th e CAN wires we re be able to co mmuni cate with eac h unless thesp li ced together. On the wiring diagrams these bad contro l unit is shortin g the CAN lines to StarTuned 13
  13. 13. CONT ROLLER AREA NETWORK When testing for battery drain, look at amperage draw after the vehicle has been shut off for several minutes to be sure all the control units have gone to sleep. The normal procedure of unplugging fuses to locate the draw must be augmented by unplugging control units from the CAN for the some purpose.power or ground. A contro l unit that is simpl y not Other Possible Problemsresponding will not bring down communicationon th is CAN . The reaso n is that the computers all A breakdown of CAN commun ication amongwa it for an empty CAN t ra nsmission line and contro l units is not the on ly proble m that canthe n put out the information that has changed. occur. CAN commun icati on requires electrica lOther control un its wait and only pick up the power. If these contro l unit s were to active lyinformation they need out of the transmitted communicate with the ignit ion key off, themessage. The original message is still on the current draw wou ld discharge a ba ttery.CAN and can be picked up by other contro l Overnight, your customer might wake up with aunits . dead battery even though nothi ng was left on. If in the event t he CAN is down, you wi ll need With the ignition off, control units no longer needto start disconnecting control units to see wh ich to communicate as much info rmat io n so they is at fau lt. With al l the control units on a particu- slow down. Also with the ignit ion key off, either lar CAN, th is can be time-consuming. Find the the EI S (Electronic Ignition Switc h) or t he CGM bridge connectors for the CAN, typica lly la be led (Central Gateway Module) senses this and sends X30 / #. These connectors are usually located at out signals to put contro l units into a "sleep" or the base of the "A" pillar below the passengers power-down mode . The Central Gateway Module and drivers side kick panels. If the doors are not is often mounted under the in strument cluster on properly sea led and water gets into the cabin, the lower panel by the drivers fee t. This contro l corrosion can interfere with digital vo ltage unit is in charge of managing the different CAN communication signa ls. When accessing these messages between different CANs. This allows conn ectors, check fo r moisture in the area. information on CAN C to be passed on to CAN B,1 StarTuned 4
  14. 14. To see if the CAN lines have an electrical problem with the wiring you can get access to the CAN lines (there under the fuse box in a 140 chassis) and measure resistance between CAN low and CAN high. Since there are two terminating resistors in the circuit in two of the control units you should measure about 60 ohms. and so on . Previous to the introdu ct ion of this unplugging a contro l units CAN wiring, wait a module, the EI S was the gateway and managed few minutes before check in g the CAN signalsCAN commun ication. Putting the contro l units to or vo lta ges. sleep red uces current draw to und er 50 ma ,wh ich is low enough to not kill a battery even In conclusionafter seve ral weeks. As mentioned earli er, theCAN H si gnal osci ll ates between .65V and 2.5V, Com muni cat ion prob lems are not that hard toand CAN L osci ll ates between 4.65 and 2.5 diagnose. Thanks to the engineering and designvo lts. Wh en the contro l units go to sleep, the of the CAN protocol, you shou ld still be ab le toCAN vo ltages change. CAN H drops to .025V and use your Compact III or Basic to comm unicateCAN L inc reases to 11 V. Th ese vo ltages are with all the control units on the CAN until youmainta ined for the durati on of the sleep period. find the one thats "incomm unicado." Very oftenTh e vo ltage may see m high, but the cu rrent draw the oth er cont rol units will have diagnosticis very low. trouble codes indi catin g the co nt rol unit is not If any control unit were to cont inue transmit- commu nicating. In the event that one CAN lineting digita l messages, the EIS or CGM would not is down, it can co mmuni cate with the otherreque st the contro l units to go to power-down CAN lin e. You can test the resistance of t heand the ve hicles battery would discharge. You terminating resistor, and unplug sp lice packscan check vo ltage or scope the signals and see and bridge con nectors to iso late faulty wiring.if the CAN lines powe r down. You will sti ll have The use of a scope or vo ltm eter can estab li sh ifto access t he spl ice con nect ion and bridge t he CAN is powerin g down, and unpluggingconnectors to unplug each contro l unit s CAN bridge connectors will iso late the control unitwirin g until th e CAN goes to sleep. After that may be at fault. StarTuned 15
  15. 15. FEATURE ARTICLE Installing a new control unit to replace the failed one is only half the job. With various combinations of options available on the same model, the new unit has to learn which are installed and how to work with them. Control Units Go Computer systems are everywhere t hese days. contro ll ed systems is as important as diagnosis - We have separate control modules strategica lly - once you know whats wrong, you must be able placed all over the veh icle. There is good reason to fix it. If the repair invo lves the rep lacement of fo r this. Excessive wi rin g can increase the we ight a contro l unit, there are a few necessary steps of a vehic le, make assemb ly diffic ult and render needed to comp lete the job. diagnostics complicated. If wiring can be reduced, the problems assoc iated with these In Concert th ree concerns dimin ish. By placing modules closest to the hardware components they con- Very often, a contro l unit works in concert with tro l, wiring can be minimized. several other control units because they are all As with any other techno logical advances, on a CAN (Contro ll er Area Network) . Together, there is a teeth ing period. A technic ians abi lity they provide a system of contro ls for the veh icle. to diagnose a problem needs to play catch-up As ide from computer contro ls of the systems with this progress. Properly servicing computer- they are ded icated to, they ca n share inputs and16 StarTuned
  16. 16. Bacl<To SchoolVehicle 1 211.065 Control ~nit IETCiElectronic transmission control (722.6 EGS52) With the old control unitControl lIIlit version still in the vehicle and onFault codesEvent memoActual values approved programmingActuationsImllal startup charger attached to theControl llllit adaptationsInitial test ( O~ cond~ion check I Oil level check battery, plug in theW" rranty or goodwill processingAdaptation Compact II, enter the unitDiagnosis routinesComplete list of guided testsFuU list of fautt codes and events you wont to code, thenSpecial fUTICtion~ Control unij log select "Initial Startup.";..r Selice information and IIp-tc-date trollble diagnosis roub leshooting by means of complaints or symptoms Continued on page 20 Stal-Tuned 17
  17. 17. Replace - We replace more parts than aftermarket brands.Engineered - Designed to meet original OEM drawings.Manufactured - Made with same OE components as factory parts.Assembred - Completely assembled from components and not just repaired. Improved Technician Efficiency
  18. 18. 260E 1987-1989 300CE 1988-1993 300EfTE 1986-1993 300SE/ SEL 1988-1991 300SL 1990-1993 MODELSA 0002300511 80 35OS0 1991 C240/C320/S430 350S0L 1990-1991 AOOO 230 91 11 80 S500/C L500/C LK320 2004 E320 1994-1995 SL320 1994-1997 E320/E500 2003·2006 SL600 1996-1997 A001 2301211 80 CLS500 2006+- 400E/500E 1992-1993 500SL 1990-1993 ML350/ML500/ML55AMG 2003+-A 00023006 11 80 E420 1994-1995 A001 23028 11 80 E500 1994 G500/G55 (NOT G55K) 2003+ SL500 1994-1999 A001 2306811 80 ML320/ML430 1900 1986·1989 1900T/3000Tl TOT 1987 S55AMG/CL55AMG 2003-2005 190E 1985-1993 1987-1989 AOOO 230 90 11 80 C240/C320 UPTO 2003 260E 300CE 1988·1989 CLK320 2003A 000 230 1111 80 3000 1987-1993 300E 1986-1992 AOOO 230 78 11 80 C32AMG KOMPRESSOR 2002·2004 300SE 1988-1992 300SEU TE 1988-1991 C230K M271 E3000 1995 AOOO 230 97 11 80 (VIN RANGE SPECIFIC) 2004 C2201 C280 1994-1995 S600/CL600 2001+A 0002301311 80 C36AMG 1995 A001 2300111 80 S65AMG/CL65AMG 2005+ 300S0 1992-1993 E55AMG 2004-2006 3005E/ 600SEC 1993 6005EL 1992-1993 CLS55AMG 2006A 000230 17 11 80 S3201 S3500 1994-1995 S420 1997-1999 A001 2301411 80 E350/E550 2007 5600 1994-1996 CLS550 2007 CL600 1998-1999 S320 1995-1999 E320CDI 2005-2006A 0002302211 80 S3500 1995 CLK550 2007 S600 1996·1999 CLK55AMG 2003+ 1900 1986-1989 A001 2301911 80 1900T/30001 OTI TOT 1987 SLK55AMG 2005+- 190E 1985-1993 260E 1987-1989 C55AMG 2005+-A 000230 2411 80 300CE 1988-1989 300E 1986·1992 2004 300SE 1988-1992 300S0L 1986-1987 300SEU TE 1988-1991 420SEU 560SECI SEL 1986-1991A 000230 2511 80 560SL 1986-1989 400SE 1992 400SEU 500SEC 1993A 119 230 00 11 80 500SEL 1992-1993 5420/500 1994-1995 C280/C43 AMG 1998-2000 CLK320 1998-2003 CLK430 1999-2003 CLK55 AMG/ML320 2001-2002A 000230 70 11 80 E320 1998-2002 E430/E55 AMG 2000-2002 ML430 1999-2001 ML55AMG 2000 SLK230/SLK320 2001-2004 CL500 2001-2003 CL55 AMG 2001-2002A 001 230 0211 80 S430
  19. 19. CONTROL UNIT TESTI NG Continued from page 17 Vehicle 1211.065 Control unit IETC VIN read out from vehicle: WDBUF65, VIN stored in control module: IWDBUF65J03A156573 You should see this Enter VIN as a 17-digit code. For example: screen indicating WDB2200631A123456 USA, Canada: WDBNA63JOXA123456 the vehicles VIN. Hit the synchronize NOTE: The VIN stored in the control module must match the VIN read out from the vehicle. button to retrieve F7 - Perform synchronization. the VIN, then F5 - Confirmation of the VIN entry. confirm that the number is correct.request output contro l. For examp le, there is no Flash!need to have a separate air temperature sensorfor engine management if you can share informa- If a problem in the software of a contro l unit istio n with the one that is dedicated to automatic detected through warranty c la im s or otherclimate control. The ambient air temperature means, Mercedes-Benz will generate an updatedsensor is one of the in puts used to ca lcu late the program to repair the trouble. Thi s is particularlyneed for air conditioning or heating. That control important with ME (Motor Electron ics) and ETCunit can be designed to pu t its temperature read- (Electronic Transmission Control) as em iss ionsing on t he CAN where others can take it off. and sh iftin g concerns need to be add ressed (fue l Today, more of th is cooperation is needed than formulas and driving styles can change). To beever before. If a contro l unit is changed, it must ab le to make these changes without provid in g anlearn what others are on the CAN so it can send entirely new ECU requires something ca ll edand rece ive the necessary information. Thi s is "Flashing." Thi s is done by means of the SDSaccomp li shed through coding a contro l unit. updating the software in the existin g contro l unit.When a new replacement is in sta ll ed, the original No physical parts need to be replaced. This iscoding information from the old unit must be advantageous for everyone invo lved sin ce a con-installed. Up to now, coding was achieved with trol unit often has multiple roles that would alsothe SDS, but soon coding wi ll be available using have to be initia li zed in order for them to a J2534 Pass-Thru device. With the SDS, you function properly. If you needed to replace need to remove coding information f ro m the orig- instead of re-flash an ME contro l unit, you wou ld inal control un it, then install the new "non- also have to relearn the anti-theft system coded" model, and, finally, put this information between the EIS (Electron ic Ign it ion Switch) on the new unit. Sounds simp le enough, and the ME contro l unit. By only re-flashing the but th ere is a spec ific procedure that must software you el imin ate the need to align the be fo ll owed. anti-theft information with the ME unit.20 StarTuned
  20. 20. - ~, -, -- -.. - _......Sho~d -thE!;:&bfug~~r a:liW~{9~~ ~~ ~-".- I _ I .. _ _ _ "- I _ .... 0 _ - " -_ _ "_~ -- - I Smal l sc ratches, stone impacts, dents and blemi shes - and the customers Mercedes can quickly lose the shine from its exte rior. 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 mea n that small appea rance defects vani sh in next to no time. It goes with out saying th at our kits meet the high, tested Mercedes-Benz quality stand ard s that yo u ex pect. So if your customers are driving around with a small imperfection , it may be able to be repa ired with Mercedes-Benz Small Repair. Sma ll Repair Kits are available from your authorized Mercedes-Ben z dealer. Training on th e Small Repair method s are available from Reliabl e Automotive Equipm ent. Please contact Reli able Automoti ve Eq uipm ent to inquire about training your staff to perform these repairs quickly and effici entl y. R1:UABLE AUTOMOTIVE [Ql,JIPMENT. INC. 1.800.328.7855 StarTu ned 21
  21. 21. CONTROL UNIT TESTING Vehicle 1211.065 Control unit IETC Iinitial startup with automatic takeover of settings of previous cont At this point, you need The following procedure will guide you through all steps required to perform a com of system ETC. to hove the old control Preconditions : unit still plugged in. - The old control un~ is still installed. - The new control un~ must be available. Selecting "Initiol stortup You will be guided through the following steps : - Read coding and adaptation data and transfer these to new control module. of 0 new control unit" will leod you to this Start process with button F2. screen. Follow the direc- tions ond the existing coding will be reod from the old unit.More On Control Unit Identity tro uble codes for it. Th is will turn on warning lights on th e dash indicatin g th at the re is a prob- These sof twa re changes have spec ific tasks to lem. By the sa me token, if eit her an ME or ETCeither correct or im prove th e driva bility of a co ntrol unit is replaced and th e SC N is notMercedes-Benz. In th e case of th e ME or ETC, updated to match the vehi cle, this is co nsideredth ese programs have a specific effect on the t ampe ring even if no perform ance modifi cati onsoverall em issions produced by the veh ic le. Th ey are performe d. Thi s means with each new re-are therefore monitored by kee pi ng track of soft- flas h, the SC N need s to be updated as well.wa re calibrations and givin g them a specific iden-tity. Th is is accomplished with th e use of an SC N Are You Ready?(Software Ca libration Num ber). If it effects emi s-sions, the EPA must be aware of t hese changes When repl acin g a c ontro l unit, yo u need toin software and approve the m. Sin ce eac h co n- co de it to th e vehi cle . Thi s is achi eve d usin g you rtrol unit has a SC N, yo u ca n find out th e leve l of Comp act III or Basi c . Before st arti ng any co dingsoftwa re in the vehic le, and determin e if a newer or prog ramming, you mu st have an approved bat-release is available, or if t he latest softwa re is tery cha rger co nn ected to the veh icle to keepalrea dy installed. vo ltage stea dy during the procedure. Aftermarket Since 2003, SCN coding has bee n requ ired by co mp anies make programmin g battery chargersfederal law. The SC N indicates if any t ampering ava il abl e th at are ca pabl e of re acting to suddenhas occurred within the software of the co nt rol vo ltage drops ca used by th e co ntro l units switch- unit. Aftermarket com panies that offer perform- in g on va ri ous componen t s. Traditional ba ttery ance mod ifications usuall y do not meet the chargers react too slowly for th is purpose, so yo u approva l of the EPA, and are co nsid ered for off- mu st make th e investment. road use only, such as raci ng. Th ese perform- Yo u have two option s when cod ing. You ca n ance "ch ips" or re-fl ashes, are ill ega l by st ate either downl oa d th e old contro l units existing and federa l standards and shoul d not be used in softwa re whil e it is sti ll in sta ll ed in the vehicle, cars driven on pub li c roa ds. These control uni ts plug in the new unit and then upload the old wil l not have the necessa ry SCN to match th e softwa re into the new unit. If you have tota lly lost res t of the vehicle. Other co ntrol units will see co mmuni cati on with th e old un it, you can insta ll the differences in t he SC N an d fl ag diagnosti c the new one and "write" mode l and codi ng22 StarTuned
  22. 22. CONTRO L UNITTESTI NG Vehicle 1211.065 Control unit IETC If yo u have lost communication IW rite model designation and equipment codes to control unit ETC. Thor. Is no model doslgnrion ~nd no equlpmont codo ~ o (.d in cQnlrOil unit ETC. with the old control unit, you can del da.;gnaooo 121 106 5 write model designation and TtM;mi;;ion-rlilhi... Ml9quipm9nt Codlil 1 14 91 • USA - - equipment codes yourself Here, TransmisSion;elevad equipment code 2 I -1 the country code is being select- Control module dat;e 032 . TaiNan Cars .- ed. Yo u may be asked questions Function -softw8fe: ~ Data ut fe 1z MB obj.<t nunilor. 0300404032 494 . USA C"Uforn i" 498 - Japan CSI S: on the options the vehicle has. If Pushbutton F3 Write model dMigMIion and e-quiptnent eode~ to control unil ZV4 - MtG vc1riiJnt Japan "·CI... 839 • Japo" G-CI••• , you don t know all the answers, these options will not function . ~j:j !J=r: sran i!!!m!I c .. ~ (11 « r .: <l""_ll .. :! p_~ Eli L - rj Jll -::-& .I : -information yo urself. This second option isdifficu lt since yo u need to be fam il iar with all ofthe options installed on the veh icle, as we ll asthose that are not. Using SDS, se lect t he contro l un it yo u wou ldli ke to rep lace. Wh ile under that head ing, select"In itia l Sta rtup ." You will be directed to a screenshowing no VIN in the new contro l unit. After .synchroni zi ng with the other units, you shou ldread the veh icle VIN and confirm the entry.Next, select "Initia l Startup of a new contro lunit," and the next screen wi ll gu ide you throughthe process of rep lacement. The first step is to A new worldwide Mercedes-Benzread the existing coding information . Afte r th is is anti-theft policy went into effect atcomp lete, turn off the ign ition key and rep lace Mercedes-Benz USA on November to,the contro l unit. Turn the key back on, select the 2008. This policy has specificF2 key to upload the software and you are requirements for the ordering andalmost done. You shou ld go into "Qu ick Tests" delivery of Theft-Relevant Partsand scan, then clear, all codes in eac h contro l (TRPs), which may require you to getunit. Road test the ve hicle and verify that all information from the vehicle owner tofunctions are wo rking properly. place an order for certain spare parts. In the case of the ME contro l un it, make sure In addition, for certain theft-relevant fu ncti ons such as cruise contro l are working. parts, such as electronic keys, If coded successfu lly, you shou ld have no prob- electronic ignition switches, infrared lems and/or wa rning lights on in the dash . This and other locking control units, it is is now a co mpl eted repair and you can give the mandatory for the dealer to install veh icle back to the customer with th e confidence them. Please contact your local dealer that comes from knowing the job was done for a copy of the policy so you can be right. This shou ld give everyone invo lve d better prepared to help them protect peace of mind . all Mercedes-Benz vehicles from theft.24 StarTuned
  23. 23. A Mercedes-Benz should be true to its origins. So tum to the Mercellles.B~ Center for Genuine Mercedes-Benz Classic Parts. TheIr experts have 40,000 true-fittin g Genuine Classic Parts of the highest quality, plus a 12-month limited warranty. They sell dIrect, shIp direct and even assist In parts specification. Merc edes-Benz Classic Center When you want authentic parts, only the source will do. 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 92618CaU or visit for additional details and a copy of tile limited Parts Warranty. © 2008 Me rcedes~8 e nz USA . lLC
  24. 24. FEATURE ARTCLE I COLUSION REPAIRTaking Stock in Bonds(Chemical Bonds, that is)Ease of manufacture, shear strength and aesthetic body lines are onlysome of the reasons Mercedes-Benz uses chemical bonding for joiningbody panels. How can we duplicate an OEM panel seam? Take a moment to stand still in New construction, new application of chemical bonding is theth is day and age and youll notice and new materials are all used in reduction of vibration and noiseth e incredible changes taking an effort to make vehicles lighter, between mated panels, evenplace in many aspects of our lives. stronger and safer for their occu- those that are riveted or bolted.Continue to stand still and you will pants . When such a vehicle is The techno logy of chemical bond-become obso lete. We need to involved in an accident, the crum- ing has expanded within the pastkeep up with the technology just to ple zones and shear points the few years, so there are many dif-break even . engineers created come into play. ferent types of adhesives used in The automotive body repair The result is a passenger cabin the collision repair industry. Eachindustry has seen tremendous with minimal intrusion and distor- type has its own characteristicschanges over the past five years. tion, and, hopefully, an outer body that are more suited to some jobs thats repairable . Traditionally, than to others. You need to know metal panels were joined using these details if you are going to various welding techniques that offer factory-like construction in depended on the application. Inner your repair. If the vehicles struc- structural panels were welded tural integrity depends upon together and outer panels and chemical bond ing, you need to other body components were maintain this construction integri- mechanically fastened , either by ty in a collision repair. riveting or bolting. Different Types Glue em Together? of AdhesivesA kit is available through your With modern vehicle construc- As mentioned earlier, there areMercedes-Benz parts supplier tion, there are places that are too many different types of bondingthat will allow you to bond difficult to get to (or " blind," adhesives for use in the automotivepanels using adhesives. meaning access is impossible) to body repair industry. In the past,Notice the two static mixers use mechanical fasteners or spot cyanoacrylate (or, "Krazy Glue")with pink tips. Before attach- welders. Also, different kinds of was used for minor repairs to tailing the mixing tube, squeeze materials need to be attached, so light assemblies and mouldings. Itout one inch of material. After welding is no longer an option . dries very fast, even faster with aattaching the tube, squeeze Chemical bonding adhesives may drying agent or adhesion promoter.out another inch to equalize work well in situations like these . The mechanical characteristics of Another often-overlooked benefit this glue are generally not suited forthe amounts.26 Stal-Tuned
  25. 25. COLLISION REPAIR / CHEMICAL BONDING automotive applications, however. see an adhesive compound mi xed It is a very thin liquid and doesnt with a hardener similar to that fill gaps satisfactorily. As a result used with body filler. This chemica l of being thin, it doesnt work well reaction usually occurs best at 75 with porous materials, either, but it deg. F. and will take about an hour can be used in low-stress minor or somewhat more to dry. It will repairs on metal or plastic just take roughly four hours to fully make sure you have a tight fit with cure, but you can continue repa irs minimal air gaps. after the first hour. Acrylics may Next, there are bonding glues. dry faster, but their strength limita- These are usually epoxy-type tions should limit them to smaller adhesives, but can also be com- repairs. posed of acrylic or methacrylate Urethane adhesives are also compounds. These adhesives are useful in automotive applications. strong and well suited for automo- While not as strong as epoxy bond- tive applications . They apply as a ing glues, it can be used for larger gel/heavy liquid so they tend to plastic repairs found on bumpers, stay where they are applied . Being brackets and/or backing panels. It thicker, they fill surface irregulari- can also be used for gri lle, head-First, squeeze one inch of ties fairly well when bonding pan- lamp assemblies, moulding andbonding material out of the els. They are not as temperamen- emblems. It is thicker than cyano- tal as some other adhesives, but acrylate, so it fills gaps well andtube, then install the static there are some conditions we stays where it is applied . It doesmixer and discharge another need to know to get the best per- have a very short working time ofinch to "equalize" the formance out of them. The num- under a minute, so be prepared tomixture. This will ensure ber-one thing to understand is that fit components together quickly. Itequal and properly mixed these bonding adhesives dry by is a two-part adhesive that needsadhesive material. chemical reaction. You will usually to be mixed before application . The Application Process As in any collision repair, sur- face preparation is often the most time-consuming step. It is always a good idea to remove as many layers of coating as possib le so the adhesive can bond to the The two-part adhesive plastic housing fits into this applica- tor gun. The gun is necessary if youre going to use the new applicator kit. Its small size makes it ideal for smaller patch panel and full panel bonding.28 StarTuned
  26. 26. Enticingly graceful and dynamic. Strong support, too. QUALITY FIT PERFORMANCE VALUE SERVICE WARRANTY Every part comes with the reassurance oj a strong !2-month/ LlIllimited-mifeage limited warranty - with additiona! lJJverage for 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 or contact your dealer. Mercedes-Benz·See !"ur A/err:etJesBenz deater forderaits and a copy of lhe Merr:etJes·IJellz Ileplacemelll Parts Limilerl Warmnly.
  27. 27. COLLISION REPAIR I CHEMICAL BONDING alignment with other body panels. Do not pull up on the panel to reposition it. Instead, slide the panel into its proper position. Clamping During this time body repair pan- els should be clamped together to hold them in the proper position, force the adhesive into surface irregularities, and squeeze out excess adhesive. Many automotive bonding agents contain glass bead, which provides a heavier consistency. Once again, this helps fill gaps and maximizes the surface area of the bond, which leads to more strength. This is aMercedes-Benz requires all chemical bonding to be supported by result of a materials "bond linesome mechanical attachment such as spot welding. Or, when control," which is its ability toattaching dissimilar metals, you can use these special structural ma intain thickness under clamp-rivets, which are available from your Mercedes-Benz parts supplier. ing forces. Use as many clamps as you can fit and make sure theymechanically strongest surface. Iy a plastic tube with groves that hold the panels tight. At this pointDiffe rent bond agents are avail- direct the adhesive mixture togeth- take a clean rag or acid brush toable for metal and plastic attach- er for proper consistency. Before remove any excess adhesive mate-ment. Follow the instructions of installing the static mixer, "equal- rial before it dries. Of course, oncethe adhesive manufacturer ize" the mix by forcing about one it dries it will be a lot harder toregard ing bonding surfaces prepa- inch out of the tube. Then, install remove. If you can, schedule yourration. In any event, you will need the static mixer and again squeeze work so you can let t he bondinga clean surface to begin. Start off out a small amount of adhesive. material cure overn ight. As men-by cleaning with soap and water. This starts off the mixing process tioned earlier, you can heat theFollow up with an astringent used correctly. Depending on the appli- area to reduce the curing time ifin pl astic prep. Thi s provides an cation, apply a bead about 10 to necessary.oil-free surface that will not con- 13mm wide at the panel contact Once the adhesive is fully cured,tam inate adhesive chemicals. points . While the chemical reac- you can continue with your repair.Sandpaper of 180 grit will provide tion is occurring, youll notice that With a proper bond, you havean optimal surface for the adhe- heat is being generated. This is returned the structu ral integrity ofsive to bond to. It is very impor- normal. Remember how long the the vehicle as close as possible totant that all the loose material working time of your adhesive is . its pre-collision state. Properfrom sanding be removed before Since the reaction is temperature repairs not only affect crash wor-app li cation. Thoroughly clean the sensitive, you can control it to thiness in future accidents, butsurface once again with prep some extent by heating or cooling also the resale value of your cus-cleaner to prepare for the adhe- the area. Heating will speed up the tomers Mercedes-Benz, althoughsive appl ication . drying process. You can use a heat these points are often overlooked . If an epoxy requires a two-part lamp and bring the area up to Your peace of mind comes frommix, don t just "eye" it. Use a glue about 140 deg. F. Apply the panel knowing you performed the bestgun with a static mixer. It is mere- to the vehicle and make sure of its job you could.30 StarTuned