XJ EMISSION CONTROL SYSTEMS 25 - 1 EMISSION CONTROL SYSTEMS CONTENTS page pageEVAPORATIVE EMISSION CONTROLS . . . . . . . 11 ON-BOARD DIAGNOSTICS . . . . . . . . . . . . . . . . . 1 ON-BOARD DIAGNOSTICS INDEX page pageGENERAL INFORMATION LOAD VALUE . . . . . . . . . . . . . . . . . . . . . . . . . . 10 SYSTEM DESCRIPTION . . . . . . . . . . . . . . . . . . 1 MALFUNCTION INDICATOR LAMP (MIL) . . . . . . 1DESCRIPTION AND OPERATION MONITORED SYSTEMS . . . . . . . . . . . . . . . . . . 7 CIRCUIT ACTUATION TEST MODE . . . . . . . . . . 2 NON-MONITORED CIRCUITS . . . . . . . . . . . . . . 9 COMPONENT MONITORS . . . . . . . . . . . . . . . . . 9 STATE DISPLAY TEST MODE . . . . . . . . . . . . . . 2 DIAGNOSTIC TROUBLE CODES . . . . . . . . . . . . 2 TRIP DEFINITION . . . . . . . . . . . . . . . . . . . . . . . 9 HIGH AND LOW LIMITS . . . . . . . . . . . . . . . . . . 10GENERAL INFORMATION PCM). Because the condition happens at an engine speed above the maximum threshold (2000 rpm), theSYSTEM DESCRIPTION PCM will not store a DTC. The Powertrain Control Module (PCM) monitors There are several operating conditions for whichmany different circuits in the fuel injection, ignition, the PCM monitors and sets DTC’s. Refer to Moni-emission and engine systems. If the PCM senses a tored Systems, Components, and Non-Monitored Cir-problem with a monitored circuit often enough to cuits in this section.indicate an actual problem, it stores a DiagnosticTrouble Code (DTC) in the PCM’s memory. If the NOTE: Various diagnostic procedures may actuallycode applies to a non-emissions related component or cause a diagnostic monitor to set a DTC. Forsystem, and the problem is repaired or ceases to instance, pulling a spark plug wire to perform aexist, the PCM cancels the code after 40 warm-up spark test may set the misfire code. When a repaircycles. Diagnostic trouble codes that affect vehicle is completed and verified, connect the DRB scanemissions illuminate the Malfunction Indicator tool to the 16–way data link connector (Fig. 1) to(check engine) Lamp. Refer to Malfunction Indicator erase all DTC’s and extinguish the MIL.Lamp in this section. Technicians can display stored DTC’s by three dif- Certain criteria must be met before the PCM ferent methods. Refer to Diagnostic Trouble Codes instores a DTC in memory. The criteria may be a spe- this section. For DTC information, refer to charts incific range of engine RPM, engine temperature, this section.and/or input voltage to the PCM. The PCM might not store a DTC for a monitoredcircuit even though a malfunction has occurred. This DESCRIPTION AND OPERATIONmay happen because one of the DTC criteria for thecircuit has not been met. For example , assume the MALFUNCTION INDICATOR LAMP (MIL)diagnostic trouble code criteria requires the PCM to As a functional test, the MIL (check engine) illumi-monitor the circuit only when the engine operates nates at key-on before engine cranking. Wheneverbetween 750 and 2000 RPM. Suppose the sensor’s the Powertrain Control Module (PCM) sets a Diag-output circuit shorts to ground when engine operates nostic Trouble Code (DTC) that affects vehicle emis-above 2400 RPM (resulting in 0 volt input to the sions, it illuminates the MIL. If a problem is
16–WAY DATA LINK CON- NECTOR25 - 2 EMISSION CONTROL SYSTEMS XJDESCRIPTION AND OPERATION (Continued) State Display Inputs and Outputs or State Display Sensors. CIRCUIT ACTUATION TEST MODE The Circuit Actuation Test Mode checks for proper operation of output circuits or devices the Powertrain Control Module (PCM) may not internally recognize. The PCM attempts to activate these outputs and allow an observer to verify proper operation. Most of the tests provide an audible or visual indication of device operation (click of relay contacts, fuel spray, etc.). Except for intermittent conditions, if a device functions properly during testing, assume the device, its associated wiring, and driver circuit work cor- rectly. Connect the DRB scan tool to the data link connector and access the Actuators screen. DIAGNOSTIC TROUBLE CODES A Diagnostic Trouble Code (DTC) indicates the Fig. 1 Data Link (Diagnostic) Connector Location PCM has recognized an abnormal condition in thedetected, the PCM sends a message to the instru- system.ment cluster to illuminate the lamp. The PCM illu- The technician can retrieve and display DTC’s inminates the MIL only for DTC’s that affect vehicle three different ways:emissions. There are some monitors that may take • The preferred and most accurate method oftwo consecutive trips, with a detected fault, before retrieving a DTC is by using the DRB scan tool. Thethe MIL is illuminated. The MIL stays on continu- scan tool supplies detailed diagnostic informationously when the PCM has entered a Limp-In mode or which can be used to more accurately diagnoseidentified a failed emission component. Refer to the causes for a DTC.Diagnostic Trouble Code charts in this group for • The second method is by observing the two-digitemission related codes. number displayed at the Malfunction Indicator Lamp Also, the MIL either flashes or illuminates contin- (MIL). The MIL is displayed on the instrument paneluously when the PCM detects active engine misfire. as the Check Engine lamp. This method is to be usedRefer to Misfire Monitoring in this section. as a “quick-test” only. Always use the DRB scan tool Additionally, the PCM may reset (turn off) the MIL for detailed information.when one of the following occur: • The third method is by observing the two-digit • PCM does not detect the malfunction for 3 con- number displayed at the vehicle odometer. Thissecutive trips (except misfire and Fuel system Moni- method, similar to the MIL lamp, is also to be usedtors). as a “quick-test” only. • PCM does not detect a malfunction while per- Remember that DTC’s are the results of a sys-forming three successive engine misfire or fuel sys- tem or circuit failure, but do not directly iden-tem tests. The PCM performs these tests while the tify the failed component or components.engine is operating within Ϯ 375 RPM of and within NOTE: For a list of DTC’s, refer to the charts in this10 % of the load of the operating condition at which section.the malfunction was first detected.STATE DISPLAY TEST MODE BULB CHECK The switch inputs to the Powertrain Control Mod- Each time the ignition key is turned to the ONule (PCM) have two recognized states; HIGH and position, the malfunction indicator (check engine)LOW. For this reason, the PCM cannot recognize the lamp on the instrument panel should illuminate fordifference between a selected switch position versus approximately 2 seconds then go out. This is done foran open circuit, a short circuit, or a defective switch. a bulb check.If the State Display screen shows the change fromHIGH to LOW or LOW to HIGH, assume the entire OBTAINING DTC’S USING DRB SCAN TOOLswitch circuit to the PCM functions properly. Connect (1) Connect the DRB scan tool to the data linkthe DRB scan tool to the data link connector and (diagnostic) connector. This connector is located inaccess the state display screen. Then access either
XJ EMISSION CONTROL SYSTEMS 25 - 3DESCRIPTION AND OPERATION (Continued)the passenger compartment; at the lower edge of An example of a flashed DTC is as follows:instrument panel; near the steering column. • Lamp flashes 4 times, pauses, and then flashes (2) Turn the ignition switch on and access the 6 more times. This indicates a DTC code number 46.“Read Fault” screen. • Lamp flashes 5 times, pauses, and flashes 5 (3) Record all the DTC’s and “freeze frame” infor- more times. This indicates a DTC code number 55. Amation shown on the DRB scan tool. DTC 55 will always be the last code to be displayed. (4) To erase DTC’s, use the “Erase Trouble Code” This indicates the end of all stored codes.data screen on the DRB scan tool. Do not erase anyDTC’s until problems have been investigated OBTAINING DTC’S USING VEHICLEand repairs have been performed. ODOMETER (1) Cycle the ignition key On - Off - On - Off - OnOBTAINING DTC’S USING MIL LAMP within 5 seconds. (1) Cycle the ignition key On - Off - On - Off - On (2) After a short pause, the mileage shown on thewithin 5 seconds. vehicles digital odometer will be temporarily deleted. (2) Count the number of times the MIL (check After this occurs, read the DTC number displayed onengine lamp) on the instrument panel flashes on and the odometer. Each two–digit number will be dis-off. The number of flashes represents the trouble played with a slight delay between numbers.code. There is a slight pause between the flashes rep- (3) A DTC number 55 will always be the last coderesenting the first and second digits of the code. to be displayed. This indicates the end of all storedLonger pauses separate individual two digit trouble codes. After code 55 has been displayed, the odometercodes. will return to its normal mode. DIAGNOSTIC TROUBLE CODE DESCRIPTIONS GENERIC MIL SCAN DRB SCAN TOOL DESCRIPTION OF DIAGNOSTIC TROUBLE HEX CODE CODE TOOL DISPLAY CODE CODE 12* Battery Disconnect Direct battery input to PCM was disconnected within the last 50 Key-on cycles. 55* Completion of fault code display on Check Engine lamp. 01 54** P0340 No Cam Signal at No camshaft signal detected during engine PCM cranking. 02 53** P0601 Internal Controller PCM Internal fault condition detected. Failure 05 47*** Charging System Battery voltage sense input below target Voltage Too Low charging during engine operation. Also, no significant change detected in battery voltage during active test of generator output circuit. 06 46*** Charging System Battery voltage sense input above target Voltage Too High charging voltage during engine operation. 0A 42* Auto Shutdown Relay An open or shorted condition detected in the Control Circuit auto shutdown relay circuit. 0B 41*** Generator Field Not An open or shorted condition detected in the Switching Properly generator field control circuit. 0C 37** P0743 Torque Converter An open or shorted condition detected in the Clutch Soleniod/Trans torque converter part throttle unlock solenoid Relay Circuits control circuit (3 speed auto RH trans. only). 0E 35** P1491 Rad Fan Control An open or shorted condition detected in the Relay Circuit low speed radiator fan relay control circuit.
25 - 4 EMISSION CONTROL SYSTEMS XJDESCRIPTION AND OPERATION (Continued) GENERIC MIL SCAN DRB SCAN TOOL DESCRIPTION OF DIAGNOSTIC TROUBLE HEX CODE CODE TOOL DISPLAY CODE CODE 0F 34* Speed Control An open or shorted condition detected in the Solenoid Circuits Speed Control vacuum or vent solenoid circuits. 10 33* A/C Clutch Relay An open or shorted condition detected in the Circuit A/C clutch relay circuit. 12 31** P0443 EVAP Purge Solenoid An open or shorted condition detected in the Circuit duty cycle purge solenoid circuit. 13 27** P0203 Injector #3 Control Injector #3 output driver does not respond Circuit properly to the control signal. or 14 P0202 Injector #2 Control Injector #2 output driver does not respond Circuit properly to the control signal. or 15 P0201 Injector #1 Control Injector #1 output driver does not respond Circuit properly to the control signal. 19 25** P0505 Idle Air Control Motor A shorted or open condition detected in one or Circuits more of the idle air control motor circuits. 1A 24** P0122 Throttle Position Throttle position sensor input below the Sensor Voltage Low minimum acceptable voltage or 1B P0123 Throttle Position Throttle position sensor input above the Sensor Voltage High maximum acceptable voltage. 1E 22** P0117 ECT Sensor Voltage Engine coolant temperature sensor input below Too Low minimum acceptable voltage. or 1F P0118 ECT Sensor Voltage Engine coolant temperature sensor input above Too High maximum acceptable voltage. 21 17* Engine Is Cold Too Engine did not reach operating temperature Long within acceptable limits. 23 15** P0500 No Vehicle Speed No vehicle speed sensor signal detected during Sensor Signal road load conditions. 24 14** P0107 MAP Sensor Voltage MAP sensor input below minimum acceptable Too Low voltage. or 25 P0108 MAP Sensor Voltage MAP sensor input above maximum acceptable Too High voltage. 27 13** P1297 No Change in MAP No difference recognized between the engine From Start to Run MAP reading and the barometric (atmospheric) pressure reading from start-up. 28 11* No Crank Reference No crank reference signal detected during Signal at PCM engine cranking. 2B P0351 Ignition Coil #1 Peak primary circuit current not achieved with Primary Circuit maximum dwell time. 2C 42* No ASD Relay Output An Open condition Detected In The ASD Relay Voltage at PCM Output Circuit.
XJ EMISSION CONTROL SYSTEMS 25 - 5DESCRIPTION AND OPERATION (Continued) GENERIC MIL SCAN DRB SCAN TOOL DESCRIPTION OF DIAGNOSTIC TROUBLE HEX CODE CODE TOOL DISPLAY CODE CODE 31 63** P1696 PCM Failure Unsuccessful attempt to write to an EEPROM EEPROM Write location by the PCM. Denied 39 23** P0112 Intake Air Temp Intake air temperature sensor input below the Sensor Voltage Low maximum acceptable voltage. or 3A P0113 Intake Air Temp Intake air temperature sensor input above the Sensor Voltage High minimum acceptable voltage. 3D 27** P0204 Injector #4 Control Injector #4 output driver does not respond Circuit properly to the control signal. 3E 21** P0132 Upstream O2S Oxygen sensor input voltage maintained above Shorted to Voltage the normal operating range. 44 53** PO600 PCM Failure SPI PCM internal fault condition detected Communications 45 27** P0205 Injector #5 Control Injector #5 output driver does not respond Circuit properly to the control signal. or 46 P0206 Injector #6 Control Injector #6 output driver does not respond Circuit properly to the control signal. 52 77* SPD CTRL PWR RLY; Malfuntion detected with power feed to speed or S/C 12V Driver control servo solenoids CKT 56 34* Speed Control Switch Speed control switch input above the maximum Always High acceptable voltage. or 57 Speed Control Switch Speed control switch input below the minimum Always Low acceptable voltage. 65 42* Fuel Pump Relay An open or shorted condition detected in the Control Circuit fuel pump relay control circuit. 66 21** P0133 Upstream O2S Slow Oxygen sensor response slower than minimum Response required switching frequency. or 67 P0135 Upstream O2S Heater Upstream oxygen sensor heating element Failure circuit malfunction 69 P0141 Downstream or Oxygen sensor heating element circuit Pre-Catalyst Heater malfunction. Failure 6A 43** P0300 Multiple Cylinder Misfire detected in multiple cylinders. Mis-fire or 6B P0301 Cylinder #1 Mis-fire Misfire detected in cylinder #1. or 6C P0302 Cylinder #2 Mis-fire Misfire detected in cylinder #2. or
25 - 6 EMISSION CONTROL SYSTEMS XJDESCRIPTION AND OPERATION (Continued) GENERIC MIL SCAN DRB SCAN TOOL DESCRIPTION OF DIAGNOSTIC TROUBLE HEX CODE CODE TOOL DISPLAY CODE CODE 6D P0303 Cylinder #3 Mis-fire Misfire detected in cylinder #3. or 6E P0304 Cylinder #4 Mis-fire Misfire detected in cylinder #4. 70 72** P0420 Efficency Failure Catalyst efficiency below required level. 71 31* P0441 Evap Purge Flow Insufficient or excessive vapor flow detected Monitor Failure during evaporative emission system operation. 72 37** P1899 P/N Switch Stuck in Incorrect input state detected for the Park/ Park or in Gear Neutral switch, auto. trans. only. 76 52** P0172 Fuel System Rich A rich air/fuel mixture has been indicated by an abnormally lean correction factor. 77 51** P0171 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally rich correction factor. 7E 21** P0138 Downstream and Oxygen sensor input voltage maintained above Pre-Catalyst O2S the normal operating range. Shorted to Voltage 80 17** P0125 Closed Loop Temp Engine does not reach 20°F within 5 minutes Not Reached with a vehicle speed signal. 84 24** P0121 TPS Voltage Does TPS signal does not correlate to MAP sensor Not Agree With MAP 87 14** P1296 No 5 Volts To MAP 5 Volt output to MAP sensor open. Sensor 8A 25** P1294 Target Idle Not Actual idle speed does not equal target idle Reached speed. 94 37* P0740 Torq Conv Clu, No Relationship between engine speed and vehicle RPM Drop At Lockup speed indicates no torque converter clutch engagement (auto. trans. only). 95 42* Fuel Level Sending Open circuit between PCM and fuel gauge Unit Volts Too Low sending unit. or 96 Fuel Level Sending Circuit shorted to voltage between PCM and Unit Volts Too High fuel gauge sending unit. or 97 Fuel Level Unit No No movement of fuel level sender detected. Change Over Miles 99 44** P1493 Ambient/Batt Temp Battery temperature sensor input voltage below Sen VoltsToo Low an acceptable range. or 9A P1492 Ambient/Batt Temp Battery temperature sensor input voltage above Sensor VoltsToo High an acceptable range. 9B 21** P0131 Upstream O2S O2 sensor voltage too low, tested after cold Shorted to Ground start. or
XJ EMISSION CONTROL SYSTEMS 25 - 7DESCRIPTION AND OPERATION (Continued) GENERIC MIL SCAN DRB SCAN TOOL DESCRIPTION OF DIAGNOSTIC TROUBLE HEX CODE CODE TOOL DISPLAY CODE CODE 9C P0137 Downstream and O2 sensor voltage too low, tested after cold Pre-Catalyst O2S start. Shorted to Ground 9D 11** P1391 Intermittent Loss of Intermittent loss of either camshaft or CMP or CKP crankshaft position sensor AE 43** P0305 Cylinder #5 Mis-fire Misfire detected in cylinder #5. or AF P0306 Cylinder #6 Mis-fire Misfire detected in cylinder #6. BA 11** P1398 Mis-fire Adaptive CKP sensor target windows have too much Numerator at Limit variation CO 21 P0133 CAT MON SLOW O2 A slow switching oxygen sensor has been 1/1 detected in bank 1/1 during catalyst monitor test. * Check Engine Lamp (MIL) will not illuminate if this Diagnostic Trouble Code was recorded. Cycle Ignitionkey as described in manual and observe code flashed by Check Engine lamp. ** Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code wasrecorded. *** Generator Lamp illuminatedMONITORED SYSTEMS MIL 21—OXYGEN SENSOR (O2S) MONITOR There are new electronic circuit monitors that Effective control of exhaust emissions is achievedcheck fuel, emission, engine and ignition perfor- by an oxygen feedback system. The most importantmance. These monitors use information from various element of the feedback system is the O2S. The O2Ssensor circuits to indicate the overall operation of the is located in the exhaust path. Once it reaches oper-fuel, engine, ignition and emission systems and thus ating temperature 300° to 350°C (572° to 662°F), thethe emissions performance of the vehicle. sensor generates a voltage that is inversely propor- The fuel, engine, ignition and emission systems tional to the amount of oxygen in the exhaust. Themonitors do not indicate a specific component prob- information obtained by the sensor is used to calcu-lem. They do indicate that there is an implied prob- late the fuel injector pulse width. This maintains alem within one of the systems and that a specific 14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio,problem must be diagnosed. the catalyst works best to remove hydrocarbons (HC), If any of these monitors detect a problem affecting carbon monoxide (CO) and nitrogen oxide (NOx) fromvehicle emissions, the Malfunction Indicator (Check the exhaust.Engine) Lamp will be illuminated. These monitors The O2S is also the main sensing element for thegenerate Diagnostic Trouble Codes that can be dis- Catalyst and Fuel Monitors.played with the check engine lamp or a scan tool. The O2S can fail in any or all of the following The following is a list of the system monitors: manners: • Misfire Monitor • slow response rate • Fuel System Monitor • reduced output voltage • Oxygen Sensor Monitor • dynamic shift • Oxygen Sensor Heater Monitor • shorted or open circuits • Catalyst Monitor Response rate is the time required for the sensor to All these system monitors require two consecutive switch from lean to rich once it is exposed to a richertrips with the malfunction present to set a fault. than optimum A/F mixture or vice versa. As the sen- Following is a description of each system monitor, sor starts malfunctioning, it could take longer toand its DTC. detect the changes in the oxygen content of the Refer to the appropriate Powertrain Diagnos- exhaust gas.tics Procedures manual for diagnostic proce- The output voltage of the O2S ranges from 0 to 1dures. volt. A good sensor can easily generate any output
25 - 8 EMISSION CONTROL SYSTEMS XJDESCRIPTION AND OPERATION (Continued)voltage in this range as it is exposed to different con- The PCM is programmed to maintain the optimumcentrations of oxygen. To detect a shift in the A/F air/fuel ratio of 14.7 to 1. This is done by makingmixture (lean or rich), the output voltage has to short term corrections in the fuel injector pulse widthchange beyond a threshold value. A malfunctioning based on the O2S sensor output. The programmedsensor could have difficulty changing beyond the memory acts as a self calibration tool that the enginethreshold value. controller uses to compensate for variations in engine specifications, sensor tolerances and engine fatigueMIL 21—OXYGEN SENSOR HEATER MONITOR over the life span of the engine. By monitoring the If there is an oxygen sensor (O2S) shorted to volt- actual fuel-air ratio with the O2S sensor (short term)age DTC, as well as a O2S heater DTC, the O2S and multiplying that with the program long-termfault MUST be repaired first. Before checking the (adaptive) memory and comparing that to the limit,O2S fault, verify that the heater circuit is operating it can be determined whether it will pass an emis-correctly. sions test. If a malfunction occurs such that the PCM Effective control of exhaust emissions is achieved cannot maintain the optimum A/F ratio, then theby an oxygen feedback system. The most important MIL will be illuminated.element of the feedback system is the O2S. The O2Sis located in the exhaust path. Once it reaches oper- MIL 64—CATALYST MONITORating temperature 300° to 350°C (572 ° to 662°F), the To comply with clean air regulations, vehicles aresensor generates a voltage that is inversely propor- equipped with catalytic converters. These converterstional to the amount of oxygen in the exhaust. The reduce the emission of hydrocarbons, oxides of nitro-information obtained by the sensor is used to calcu- gen and carbon monoxide.late the fuel injector pulse width. This maintains a Normal vehicle miles or engine misfire can cause a14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio, catalyst to decay. A meltdown of the ceramic core canthe catalyst works best to remove hydrocarbons (HC), cause a reduction of the exhaust passage. This cancarbon monoxide (CO) and nitrogen oxide (NOx) from increase vehicle emissions and deteriorate enginethe exhaust. performance, driveability and fuel economy. The voltage readings taken from the O2S sensor The catalyst monitor uses dual oxygen sensorsare very temperature sensitive. The readings are not (O2S’s) to monitor the efficiency of the converter. Theaccurate below 300°C. Heating of the O2S sensor is dual O2S’s sensor strategy is based on the fact thatdone to allow the engine controller to shift to closed as a catalyst deteriorates, its oxygen storage capacityloop control as soon as possible. The heating element and its efficiency are both reduced. By monitoringused to heat the O2S sensor must be tested to ensure the oxygen storage capacity of a catalyst, its effi-that it is heating the sensor properly. ciency can be indirectly calculated. The upstream The O2S sensor circuit is monitored for a drop in O2S is used to detect the amount of oxygen in thevoltage. The sensor output is used to test the heater exhaust gas before the gas enters the catalytic con-by isolating the effect of the heater element on the verter. The PCM calculates the A/F mixture from theO2S sensor output voltage from the other effects. output of the O2S. A low voltage indicates high oxy- gen content (lean mixture). A high voltage indicates aMIL 43—MISFIRE MONITOR low content of oxygen (rich mixture). Excessive engine misfire results in increased cata- When the upstream O2S detects a lean condition,lyst temperature and causes an increase in HC emis- there is an abundance of oxygen in the exhaust gas.sions. Severe misfires could cause catalyst damage. A functioning converter would store this oxygen so itTo prevent catalytic convertor damage, the PCM can use it for the oxidation of HC and CO. As themonitors engine misfire. converter absorbs the oxygen, there will be a lack of The Powertrain Control Module (PCM) monitors oxygen downstream of the converter. The output offor misfire during most engine operating conditions the downstream O2S will indicate limited activity in(positive torque) by looking at changes in the crank- this condition.shaft speed. If a misfire occurs the speed of the As the converter loses the ability to store oxygen,crankshaft will vary more than normal. the condition can be detected from the behavior of the downstream O2S. When the efficiency drops, noMIL 51/52—FUEL SYSTEM MONITOR chemical reaction takes place. This means the con- To comply with clean air regulations, vehicles are centration of oxygen will be the same downstream asequipped with catalytic converters. These converters upstream. The output voltage of the downstreamreduce the emission of hydrocarbons, oxides of nitro- O2S copies the voltage of the upstream sensor. Thegen and carbon monoxide. The catalyst works best only difference is a time lag (seen by the PCM)when the Air Fuel (A/F) ratio is at or near the opti- between the switching of the O2S’s.mum of 14.7 to 1.
XJ EMISSION CONTROL SYSTEMS 25 - 9DESCRIPTION AND OPERATION (Continued) To monitor the system, the number of lean-to-rich COMPONENT MONITORSswitches of upstream and downstream O2S’s is There are several components that will affect vehi-counted. The ratio of downstream switches to cle emissions if they malfunction. If one of these com-upstream switches is used to determine whether the ponents malfunctions the Malfunction Indicatorcatalyst is operating properly. An effective catalyst Lamp (Check Engine) will illuminate.will have fewer downstream switches than it has Some of the component monitors are checking forupstream switches i.e., a ratio closer to zero. For a proper operation of the part. Electrically operatedtotally ineffective catalyst, this ratio will be one-to- components now have input (rationality) and outputone, indicating that no oxidation occurs in the device. (functionality) checks. Previously, a component like The system must be monitored so that when cata- the Throttle Position sensor (TPS) was checked bylyst efficiency deteriorates and exhaust emissions the PCM for an open or shorted circuit. If one ofincrease to over the legal limit, the MIL (check these conditions occurred, a DTC was set. Now thereengine lamp) will be illuminated. is a check to ensure that the component is working. This is done by watching for a TPS indication of aTRIP DEFINITION greater or lesser throttle opening than MAP and The term “Trip” has different meanings depending engine rpm indicate. In the case of the TPS, if engineon what the circumstances are. If the MIL (Malfunc- vacuum is high and engine rpm is 1600 or greatertion Indicator Lamp) is OFF, a Trip is defined as and the TPS indicates a large throttle opening, awhen the Oxygen Sensor Monitor and the Catalyst DTC will be set. The same applies to low vacuum ifMonitor have been completed in the same drive cycle. the TPS indicates a small throttle opening. When any Emission DTC is set, the MIL on the All open/short circuit checks or any component thatdash is turned ON. When the MIL is ON, it takes 3 has an associated limp in will set a fault after 1 tripgood trips to turn the MIL OFF. In this case, it with the malfunction present. Components withoutdepends on what type of DTC is set to know what a an associated limp in will take two trips to illumi-“Trip” is. nate the MIL. For the Fuel Monitor or Mis-Fire Monitor (contin- Refer to the Diagnostic Trouble Codes Descriptionuous monitor), the vehicle must be operated in the Charts in this section and the appropriate Power-“Similar Condition Window” for a specified amount of train Diagnostic Procedure Manual for diagnostictime to be considered a Good Trip. procedures. If a Non-Contiuous OBDII Monitor, such as: • Oxygen Sensor NON-MONITORED CIRCUITS • Catalyst Monitor The PCM does not monitor the following circuits, • Purge Flow Monitor systems and conditions that could have malfunctions • Leak Detection Pump Monitor (if equipped) causing driveability problems. The PCM might not • EGR Monitor (if equipped) store diagnostic trouble codes for these conditions. • Oxygen Sensor Heater Monitor However, problems with these systems may cause the fails twice in a row and turns ON the MIL, re-run- PCM to store diagnostic trouble codes for other sys-ning that monitor which previously failed, on the tems or components. For example, a fuel pressurenext start-up and passing the monitor is considered problem will not register a fault directly, but couldto be a Good Trip. cause a rich/lean condition or misfire. This could If any other Emission DTC is set (not an OBDII cause the PCM to store an oxygen sensor or misfireMonitor), a Good Trip is considered to be when the diagnostic trouble codeOxygen Sensor Monitor and Catalyst Monitor havebeen completed; or 2 Minutes of engine run time if FUEL PRESSUREthe Oxygen Sensor Monitor or Catalyst Monitor have The fuel pressure regulator controls fuel systembeen stopped from running. pressure. The PCM cannot detect a clogged fuel It can take up to 2 Failures in a row to turn on the pump inlet filter, clogged in-line fuel filter, or aMIL. After the MIL is ON, it takes 3 Good Trips to pinched fuel supply or return line. However, theseturn the MIL OFF. After the MIL is OFF, the PCM could result in a rich or lean condition causing thewill self-erase the DTC after 40 Warm-up cycles. A PCM to store an oxygen sensor or fuel system diag-Warm-up cycle is counted when the ECT (Engine nostic trouble code.Coolant Temperature Sensor) has crossed 160°F andhas risen by at least 40°F since the engine has been SECONDARY IGNITION CIRCUITstarted. The PCM cannot detect an inoperative ignition coil, fouled or worn spark plugs, ignition cross firing, or open spark plug cables.
25 - 10 EMISSION CONTROL SYSTEMS XJDESCRIPTION AND OPERATION (Continued)CYLINDER COMPRESSION system devices. However, these could cause the PCM The PCM cannot detect uneven, low, or high engine to store a MAP sensor diagnostic trouble code andcylinder compression. cause a high idle condition.EXHAUST SYSTEM PCM SYSTEM GROUND The PCM cannot detect a plugged, restricted or The PCM cannot determine a poor system ground.leaking exhaust system, although it may set a fuel However, one or more diagnostic trouble codes maysystem fault. be generated as a result of this condition. The mod- ule should be mounted to the body at all times, alsoFUEL INJECTOR MECHANICAL during diagnostic.MALFUNCTIONS The PCM cannot determine if a fuel injector is PCM CONNECTOR ENGAGEMENTclogged, the needle is sticking or if the wrong injector The PCM may not be able to determine spread oris installed. However, these could result in a rich or damaged connector pins. However, it might storelean condition causing the PCM to store a diagnostic diagnostic trouble codes as a result of spread connec-trouble code for either misfire, an oxygen sensor, or tor pins.the fuel system. HIGH AND LOW LIMITSEXCESSIVE OIL CONSUMPTION The PCM compares input signal voltages from each Although the PCM monitors engine exhaust oxygen input device with established high and low limits forcontent when the system is in closed loop, it cannot the device. If the input voltage is not within limitsdetermine excessive oil consumption. and other criteria are met, the PCM stores a diagnos- tic trouble code in memory. Other diagnostic troubleTHROTTLE BODY AIR FLOW code criteria might include engine RPM limits or The PCM cannot detect a clogged or restricted air input voltages from other sensors or switches thatcleaner inlet or filter element. must be present before verifying a diagnostic trouble code condition.VACUUM ASSIST The PCM cannot detect leaks or restrictions in thevacuum circuits of vacuum assisted engine controlLOAD VALUEENGINE IDLE/NEUTRAL 2500 RPM/NEUTRALAll Engines 2% to 8% of Maximum Load 9% to 17% of Maximum Load
FUEL FWD SUPPLY TUBE EVAP CANISTER VENT LINE FILTER/FUEL PRES- ALIGNMENT ARROW FUEL SURE REGULATOR ROLLOVERALVE FUEL V PUMP RETAINERCLAMP MODULE LOCKNUT PIGTAIL HARNESSXJ EMISSION CONTROL SYSTEMS 25 - 11 EVAPORATIVE EMISSION CONTROLS INDEX page pageDESCRIPTION AND OPERATION DIAGNOSIS AND TESTING CRANKCASE VENTILATION SYSTEM . . . . . . . 12 VACUUM SCHEMATICS . . . . . . . . . . . . . . . . . . 13 DUTY CYCLE EVAP CANISTER PURGE REMOVAL AND INSTALLATION SOLENOID . . . . . . . . . . . . . . . . . . . . . . . . . . 11 DUTY CYCLE EVAP CANISTER PURGE EVAP CANISTER . . . . . . . . . . . . . . . . . . . . . . . 11 SOLENOID . . . . . . . . . . . . . . . . . . . . . . . . . . 14 EVAPORATION (EVAP) CONTROL SYSTEM . . 11 EVAP CANISTER . . . . . . . . . . . . . . . . . . . . . . . 13 ROLLOVER VALVE . . . . . . . . . . . . . . . . . . . . . . 11 ROLLOVER VALVE(S) . . . . . . . . . . . . . . . . . . . 14 VEHICLE EMISSION CONTROL INFORMATION SPECIFICATIONS (VECI) LABEL . . . . . . . . . . . . . . . . . . . . . . . . 13 TORQUE CHART . . . . . . . . . . . . . . . . . . . . . . . 14DESCRIPTION AND OPERATIONEVAPORATION (EVAP) CONTROL SYSTEM The function of the EVAP control system is to pre-vent the emissions of gasoline vapors from the fueltank into the atmosphere. When fuel evaporates inthe fuel tank, the vapors pass through vent hoses ortubes to a carbon filled EVAP canister. They are tem-porarily held in the canister until they can be drawninto the intake manifold when the engine is running. All engines use a duty cycle purge system. ThePCM controls vapor flow by operating the duty cycleEVAP purge solenoid. Refer to Duty Cycle EVAPCanister Purge Solenoid for additional information. The EVAP canister is a feature on all models forthe storage of fuel vapors from the fuel tank.NOTE: The hoses used in this system are speciallymanufactured. If replacement becomes necessary, itis important to use only fuel resistant hose. Fig. 1 Rollover Valve Location On RHD models, the canister is located in the leftROLLOVER VALVE side of the engine compartment near the heater blower motor (Fig. 3). The EVAP canister is filled The fuel tank is equipped with a rollover valve. with granules of an activated carbon mixture. FuelThe valve is located on the top of the fuel tank (Fig. vapors entering the EVAP canister are absorbed by1). The valve will prevent fuel flow through the fuel the charcoal granules.tank vent (EVAP) hoses in the event of an accidental Fuel tank pressure vents into the EVAP canister.vehicle rollover. The EVAP canister draws fuel vapors Fuel vapors are temporarily held in the canister untilfrom the fuel tank through this valve. they can be drawn into the intake manifold. The duty The valve cannot be serviced separately. If replace- cycle EVAP canister purge solenoid allows the EVAPment is necessary, the fuel tank must be replaced. canister to be purged at predetermined times and atRefer to Fuel Tank Removal/Installation in Group 14, certain engine operating conditions.Fuel System.EVAP CANISTER DUTY CYCLE EVAP CANISTER PURGE SOLENOID The Duty Cycle EVAP Canister Purge Solenoid reg- A maintenance free, EVAP canister is used on all ulates the rate of vapor flow from the EVAP canistervehicles. On conventional left hand drive (LHD) mod- to the intake manifold. The Powertrain Control Mod-els, the EVAP canister is located in the engine com- ule (PCM) operates the solenoid.partment on the passenger side frame rail (Fig. 2).
MOUNTINGTRAP S FWD MOUNTINGTRAP SMOUNTING STRAP CANISTER EVAPSTRAP BOLT BOLT FWD EVAP CANISTER MOUNTING MOUNTING SOLE- INLETCONNECTOR PURGE BOLT COVER ELECTRICAL FIXED ORIFICE AIR FITTING NOID AIR FILTER TING FIT- VACUUM HARNESS25 - 12 EMISSION CONTROL SYSTEMS XJDESCRIPTION AND OPERATION (Continued) it. The solenoid will not operate properly unless it is installed correctly. Fig. 2 EVAP Canister Location—LHD Models Fig. 4 Duty Cycle EVAP Purge Solenoid (LHD Shown) CRANKCASE VENTILATION SYSTEM All 2.5L 4–cylinder and 4.0L 6–cylinder engines are equipped with a Crankcase Ventilation (CCV) system (Fig. 5) or (Fig. 6). The CCV system performs the same function as a conventional PCV system, but does not use a vacuum controlled valve. Fig. 3 EVAP Canister Location—RHD Models During the cold start warm-up period and the hotstart time delay, the PCM does not energize the sole-noid. When de-energized, no vapors are purged. ThePCM de-energizes the solenoid during open loop oper-ation. The engine enters closed loop operation after itreaches a specified temperature and the time delayends. During closed loop operation, the PCM cycles(energizes and de-energizes) the solenoid 5 or 10times per second, depending upon operating condi-tions. The PCM varies the vapor flow rate by chang-ing solenoid pulse width. Pulse width is the amountof time that the solenoid is energized. The PCMadjusts solenoid pulse width based on engine operat-ing condition. Fig. 5 CCV System—2.5L Engine—Typical On vehicles equipped with Left Hand Drive (LHD),the solenoid attaches to a bracket located in the On 4.0L 6 cylinder engines, a molded vacuum tuberight-rear side of engine compartment near the EVAP connects manifold vacuum to top of cylinder headcanister (Fig. 4). On vehicles equipped with Right (valve) cover at dash panel end. The vacuum fittingHand Drive (RHD), the solenoid attaches to a bracket contains a fixed orifice of a calibrated size. It meterslocated in the left-rear side of engine compartment. the amount of crankcase vapors drawn out of theThe top of the solenoid has the word UP or TOP on engine.
AIR INLET TING FIT- FWDIXED F ORIFICE FITTING AIR COVER FILTER FWD VECI LABEL MOUNTINGTRAP S EVAPSTRAP BOLT MOUNTING CANISTERXJ EMISSION CONTROL SYSTEMS 25 - 13DESCRIPTION AND OPERATION (Continued) Fig. 7 VECI Label Location—Typical DIAGNOSIS AND TESTING VACUUM SCHEMATICS A vacuum schematic for emission related items can be found on the Vehicle Emission Control Informa- Fig. 6 CCV System—4.0L Engine—Typical tion (VECI) Label. Refer to VECI Label in this group On 2.5L 4 cylinder engines, a fitting on drivers for label location.side of cylinder head (valve) cover contains themetered orifice. It is connected to manifold vacuum. A fresh air supply hose from the air cleaner is con- REMOVAL AND INSTALLATIONnected to front of cylinder head cover on 4.0Lengines. It is connected to rear of cover on 2.5L EVAP CANISTERengines. On vehicle equipped with Left Hand Drive (LHD), When the engine is operating, fresh air enters the the EVAP canister is located in engine compartmentengine and mixes with crankcase vapors. Manifold on right side frame rail (Fig. 8). On vehicles equippedvacuum draws the vapor/air mixture through the with Right Hand Drive (RHD), the canister is locatedfixed orifice and into the intake manifold. The vapors on left side of engine compartment near heaterare then consumed during combustion. blower motor (Fig. 9).VEHICLE EMISSION CONTROL INFORMATION(VECI) LABEL All vehicles are equipped with a combined VECIlabel. This label is located in the engine compart-ment (Fig. 7) and contains the following: • Engine family and displacement • Evaporative family • Emission control system schematic • Certification application • Engine timing specifications (if adjustable) • Idle speeds (if adjustable) • Spark plug and gap The label also contains an engine vacuum sche-matic. There are unique labels for vehicles built forsale in the state of California and the country ofCanada. Canadian labels are written in both the Fig. 8 EVAP Canister Location—LHD ModelsEnglish and French languages. These labels are per- REMOVALmanently attached and cannot be removed without (1) Disconnect vacuum lines at EVAP canister.defacing information and destroying label. Note location of lines before removal.
MOUNTINGTRAP S MOUNTING STRAP FWD BOLT EVAP CANISTER25 - 14 EMISSION CONTROL SYSTEMS XJREMOVAL AND INSTALLATION (Continued) Fig. 9 EVAP Canister Location—RHD Models Fig. 10 Duty Cycle EVAP Canister Purge Solenoid— (LHD Shown) (2) Remove canister retaining strap bolt. (3) Remove canister from vehicle. INSTALLATION (1) Install EVAP canister purge solenoid and itsINSTALLATION mounting bracket to cowl panel. (1) Position canister into bracket. (2) Tighten bolt to 5 N·m (45 in. lbs.) torque. (2) Install and tighten strap bolt to 5 N·m (45 in. (3) Connect vacuum harness and wiring connector.lbs.) torque. (3) Connect vacuum lines at EVAP canister. ROLLOVER VALVE(S) The pressure relief/rollover valves(s) are/is moldedDUTY CYCLE EVAP CANISTER PURGE SOLENOID into the fuel tank and are not serviced separately. If replacement is necessary, the fuel tank must beREMOVAL replaced. Refer to Fuel Tank Removal/Installation in On vehicles equipped with Left Hand Drive (LHD), Group 14, Fuel System for procedures.the solenoid attaches to a bracket located in theright-rear side of engine compartment near the EVAPcanister (Fig. 10). On vehicles equipped with Right SPECIFICATIONSHand Drive (RHD), the solenoid attaches to a bracketlocated in the left-rear side of engine compartment. TORQUE CHARTThe top of the solenoid has the word UP or TOP onit. The solenoid will not operate properly unless it is Description Torqueinstalled correctly. EVAP Canister Mounting Bolt . . . 5 N·m (45 in. lbs.) (1) Disconnect electrical wiring connector at sole- EVAP Canister Purge Solenoidnoid. Bracket-to-Body Mounting Bolt . 5 N·m (45 in. lbs.) (2) Disconnect vacuum harness at solenoid. (3) Remove solenoid and its support bracket.
XJ EMISSION CONTROL SYSTEM 25 - 1 EMISSION CONTROL SYSTEM CONTENTS page pageEXHAUST EMISSION CONTROLS—2.5L DIESEL ON-BOARD DIAGNOSTICS—2.5L DIESEL ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 ON-BOARD DIAGNOSTICS—2.5L DIESEL ENGINE INDEX page pageGENERAL INFORMATION DESCRIPTION AND OPERATION SYSTEM DESCRIPTION—2.5L DIESEL ENGINE DIAGNOSTIC TROUBLE CODES . . . . . . . . . . . . 2 ....................................... 1GENERAL INFORMATION MONITORED CIRCUITS The MSA can detect certain problems in the elec-SYSTEM DESCRIPTION—2.5L DIESEL ENGINE trical system. The 2.5L diesel MSA controller and Powertrain Open or Shorted Circuit – The MSA can deter-Control Module (PCM) monitor and control many dif- mine if sensor output (which is the input to MSA isferent circuits in the fuel injection pump and engine within proper range. It also determines if the circuitsystems. If the MSA senses a problem with a moni- is open or shorted.tored circuit that indicates an actual problem, a Output Device Current Flow – The MSA sensesDiagnostic Trouble Code (DTC) will be stored in the whether the output devices are electrically connected.PCM’s memory, and eventually may illuminate the If there is a problem with the circuit, the MSADiesel Glow Plug lamp constantly while the key is senses whether the circuit is open, shorted to groundon. If the problem is repaired, or is intermittent, the (–), or shorted to (+) voltage.PCM will erase the DTC after 40 warm-up cycles. Awarm-up cycle consists of starting the vehicle when NON–MONITORED CIRCUITSthe engine is cold, then the engine to warms up to a The MSA does not monitor the following circuits,certain temperature, and finally, the engine tempera- systems or conditions that could have malfunctionsture falls to a normal operating temperature, then that result in driveability problems. A DTC will notthe key is turned off. be displayed for these conditions. Certain criteria must be met for a DTC to be Fuel Pressure: Fuel pressure is controlled by theentered into PCM memory. The criteria may be a fuel injection pump. The PCM cannot detect prob-specific range of engine rpm, engine or fuel tempera- lems in this component.ture and/or input voltage to the PCM. A DTC indi- Cylinder Compression: The MSA cannot detectcates that the PCM has identified an abnormal uneven, low, or high engine cylinder compression.signal in a circuit or the system. A DTC may indicate Exhaust System: The MSA cannot detect athe result of a failure, but never identify the failed plugged, restricted or leaking exhaust system.component directly. Fuel Injector Malfunctions: The MSA cannot There are several operating conditions that the determine if the fuel injector is clogged, or the wrongMSA does not monitor and set a DTC for. Refer to injector is installed. The fuel injectors on the dieselthe following Monitored Circuits and Non–Monitored engine are not controlled by the MSA, although aCircuits in this section. defective fuel injector sensor is monitored by the PCM.
25 - 2 EMISSION CONTROL SYSTEM XJGENERAL INFORMATION (Continued) Vacuum Assist: Leaks or restrictions in the vac- DESCRIPTION AND OPERATIONuum circuits of vacuum assisted engine control sys-tem devices are not monitored by the MSA. DIAGNOSTIC TROUBLE CODES MSA System Ground: The MSA cannot deter- On the following pages, a list of DTC’s is providedmine a poor system ground. However, a DTC may be for the 2.5L diesel engine. A DTC indicates that thegenerated as a result of this condition. PCM has recognized an abnormal signal in a circuit MSA/PCM Connector Engagement: The MSA or the system. A DTC may indicate the result of acannot determine spread or damaged connector pins. failure, but most likely will not identify the failedHowever, a DTC may be generated as a result of this component directly.condition. ACCESSING DIAGNOSTIC TROUBLE CODESHIGH AND LOW LIMITS A stored DTC can be displayed through the use of The MSA compares input signal voltages from each the DRB III scan tool. The DRB III connects to theinput device. It will establish high and low limits data link connector. The data link connector isthat are programmed into it for that device. If the located under the instrument panel near bottom ofinput voltage is not within specifications and other the steering column (Fig. 1).DTC criteria are met, a DTC will be stored in mem-ory. Other DTC criteria might include engine rpmlimits or input voltages from other sensors orswitches. The other inputs might have to be sensedby the MSA when it senses a high or low input volt-age from the control system device in question. Fig. 1 Data Link Connector Location—Typical ERASING TROUBLE CODES After the problem has been repaired, use the DRB III scan tool to erase a DTC.
XJ EMISSION CONTROL SYSTEM 25 - 3DESCRIPTION AND OPERATION (Continued)MSA CONTROLLER DRBIII CODESGeneric Scan Tool Code DRB III Scan Tool DisplayP0100 Mass of Volumes of Air Flow Plausibility Mass of Volumes of Air Flow Signal High Exceeded Mass of Volumes of Air Flow Signal Low ExceededP0115 Temperature of Engine Coolant SRC High Exceeded Temperature of Engine Coolant SRC Low ExceededP0180 Fuel Temperature Sensor SRC High Exceeded Fuel Temperature Sensor SRC Low ExceededP0400 EGR Open Circuit EGR Short CircuitP0500 Vehicle Speed Sensor PEC Frequency Too High Vehicle Speed Sensor Signal High Exceeded Vehcle Speed Sensor PlausibilityP0725 Engine Speed Sensor Dynamic Plausibility Engine Speed Sensor Over Speed Recognition Engine Speed Sensor Static PlausibiltyP1105 Atmospheric Pressure Sensor SRC High Exceeded Atmospheric Pressure Sensor SRC Low ExceededP1201 Needle Movement Sensor High Exceeded Needle Movement Sensor Low ExceededP1220 Fuel Quantity Actuator Neg. Gov. Deviation Cold Fuel Quantity Actuator Neg. Gov. Deviation Warm Fuel Quantity Actuator Pos. Gov. Deviation Cold Fuel Quantity Actuator Pos. Gov. Deviation WarmP1225 Control Sleeve Sensor Signal High Exceeded Control Sleeve Sensor Start End Pos. Not Attained Control Sleeve Sensor Stop End Pos. Not AttainedP1230 Timing Control Negative Governing Governor Deviation Timing Control Positive Governing Governor DeviationP1515 Accelerator Pedal Postion Sensor Signal High Exceeded Accelerator Pedal Sensor Signal Low Exceeded Accelerator Pedal Sensor Signal PWG Plaus With Low Idle Switch Accelerator Pedal Sensor Signal PWG Plaus With PotentiometerP1600 Battery Voltage SRC High ExceededP1605 Terminal #15 Plausibility After StartupP1610 Regulator Lower Regulator Limit Regulator Upper Regulator LimitP1615 Microcontroller Gate-Array Monitoring Microcontroller Gate-Array Watchdog Microcontroller Prepare Fuel Quantity Stop Microcontroller Recovery Was Occurred Microcontrller Redundant Overrun MonitoringP1630 Solenoid Valve Controller Open Circuit Solenoid Valve Controller Short Circuit
25 - 4 EMISSION CONTROL SYSTEM XJDESCRIPTION AND OPERATION (Continued)Generic Scan Tool Code DRB III Scan Tool DisplayP1635 Glow Relay Controller Open Circuit Glow Relay Controller Short CircuitP1650 Diagnostic Lamp Open Circuit Diagnostic Lamp Short CircuitP1660 Redundant Emer. Stop Plausibility In After-Run Redundant Emer Stop Powerstage DefectiveP1665 Cruise Status Indicator Lamp Short CircuitP1680 EEPROM Plausibility Checksum Error for Adj. EEPROM Plausibility Checksum Error in CC212 EEPROM Plausibility Communication With EEPROM EEPROM Plausibility Func. Switch Wrong or Missing EEPROM Plausibility Ver Number Not CorrespondingP1685 Vehicle Theft Alarm Code Line BreakdownP1703 Brake Signal Plaus With Redundant ContactP1740 Clutch Signal PlausibiltyP1725 Inductive Aux. Speed Sensor Dynamic Plausibilty Inductive Aux. Speed Sensor Overspeed Recognition Inductive Aux Speed Sensor Plausibilty Inductive Aux. Speed Sensor Static PlausibiltyPCM DRBIII CODESGeneric Scan Tool Code DRBIII Scan Tool DisplayP0117 Engine Coolant Volts LoP0118 Engine Coolant Volts HiP0500 Vehicle Speed SignalP0601 Internal Self TestP1296 5 VDC OutputP1391 Loss of Cam or Crank
XJ EMISSION CONTROL SYSTEM 25 - 5 EXHAUST EMISSION CONTROLS—2.5L DIESEL ENGINE INDEX page pageDESCRIPTION AND OPERATION REMOVAL AND INSTALLATION EXHAUST GAS RECIRCULATION (EGR) EGR TUBE . . . . . . . . . . . . . . . . . . . . . . . . ..... 7 SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . ..... 5 EGR VALVE . . . . . . . . . . . . . . . . . . . . . . . ..... 7 VACUUM HOSE ROUTING SCHEMATIC . ..... 5 ELECTRIC VACUUM MODULATOR (EVM) ..... 7DIAGNOSIS AND TESTING SPECIFICATIONS EGR GAS FLOW TEST . . . . . . . . . . . . . . ..... 6 TORQUE CHART—2.5L DIESEL . . . . . . . ..... 8 ELECTRIC VACUUM MODULATOR (EVM) TEST . . . . . . . . . . . . . . . . . . . . . . . . . . ..... 7DESCRIPTION AND OPERATION EXHAUST GAS RECIRCULATION (EGR) SYSTEMVACUUM HOSE ROUTING SCHEMATIC GENERAL INFORMATION Vacuum for the EGR system is supplied by the The EGR system reduces oxides of nitrogen (NOx)internal engine mounted vacuum pump. Refer to in the engine exhaust. This is accomplished by allow-EGR System Operation for vacuum pump informa- ing a predetermined amount of hot exhaust gas totion. Vacuum harness routing for emission related recirculate and dilute the incoming fuel/air mixture.components is displayed in (Fig. 1). A malfunctioning EGR system can cause engine stumble, sags or hesitation, rough idle, engine stall- ing and poor driveability. EGR SYSTEM OPERATION The system consists of: • An EGR valve assembly. The valve is located behind the intake manifold (Fig. 2). Fig. 1 Typical Hose Routing Fig. 2 EGR Valve and Tube Location
25 - 6 EMISSION CONTROL SYSTEM XJDESCRIPTION AND OPERATION (Continued) • An Electric Vacuum Modulator (EVM). The EVM The EGR system will be shut down by the MSAis sometimes referred to as the EGR control solenoid after 60 seconds of continuous engine idling toor EGR duty cycle solenoid. The EVM serves two dif- improve idle quality.ferent functions. One is to control vacuum bleed–offof the EGR valve. The other is to control the “ontime” of the EGR valve. DIAGNOSIS AND TESTING • The MSA operates the EVM. The MSA is locatedis located inside the vehicle in the center consule. EGR GAS FLOW TEST • An EGR tube (Fig. 2) connecting a passage in Use the following test procedure to determine ifthe EGR valve to the rear of the exhaust manifold. exhaust gas is flowing through the EGR valve. It can • The vacuum pump supplies vacuum for the also be used to determine if the EGR tube is plugged,EVM and the EGR valve. This pump also supplies or the system passages in the intake or exhaust man-vacuum for operation of the power brake booster. The ifolds are plugged.pump is located internally in the front of the engine This is not to be used as a complete test of theblock (Fig. 3) and is driven by the crankshaft gear. EGR system. The engine must be started, running and warmed to operating temperature for this test. (1) All EGR valves are equipped with a vacuum supply fitting located on the EGR valve vacuum motor (Fig. 2). (2) Disconnect the rubber hose from the vacuum supply fitting (Fig. 2). (3) Connect a hand–held vacuum pump to this fit- ting. (4) Start the engine. (5) Slowly apply 10 inches of vacuum to the fitting on the EGR valve motor. Vacuum should hold steady at 10 inches. If not, replace the EGR valve. If vac- uum holds steady at 10 inches, proceed to next step. (6) While applying vacuum, and with the engine running at idle speed, the idle speed should drop, a rough idle may occur, or the engine may even stall. Fig. 3 Internal Vacuum Pump This is indicating that exhaust gas is flowing through • Vacuum lines and hoses to connect the various the EGR tube between the intake and exhaust man-components. ifolds. When the MSA supplies a variable ground signal (7) If the engine speed did not change, the EGRto the EVM, EGR system operation starts to occur. valve may be defective, the EGR tube may beThe MSA will monitor and determine when to supply plugged with carbon, or the passages in the intakeand remove this variable ground signal. This will and exhaust manifolds may be plugged with carbon.depend on inputs from the engine coolant tempera- (a) Remove EGR valve from engine. Refer toture, throttle position and engine speed sensors. EGR Valve Removal in this group. When the variable ground signal is supplied to the (b) Apply vacuum to the vacuum motor fittingEVM, vacuum from the vacuum pump will be and observe the stem on the EGR valve. If theallowed to pass through the EVM and on to the EGR stem is moving, it can be assumed that the EGRvalve with a connecting hose. valve is functioning correctly. The problem is in Exhaust gas recirculation will begin in this order either a plugged EGR tube or plugged passages atwhen: the intake or exhaust manifolds. Refer to step (c). • The MSA determines that EGR system operation If the stem will not move, replace the EGR valve.is necessary. (c) Remove the EGR tube between the intake • The engine is running to operate the vacuum and exhaust manifolds. Check and clean the EGRpump. tube and its related openings on the manifolds. • A variable ground signal is supplied to the EVM. Refer to EGR Tube in this group for procedures. • Variable vacuum passes through the EVM to the Do not attempt to clean the EGR valve. If theEGR valve. valve shows evidence of heavy carbon build–up near • The inlet seat (poppet valve) at the bottom of the base, replace it.the EGR valve opens to dilute and recirculateexhaust gas back into the intake manifold.
XJ EMISSION CONTROL SYSTEM 25 - 7DIAGNOSIS AND TESTING (Continued)ELECTRIC VACUUM MODULATOR (EVM) TEST (3) Loosen fitting at exhaust manifold end of tube (Fig. 2).VACUUM TEST (4) Remove EGR tube and discard old gasket. With the engine running, disconnect the vacuum (5) Clean gasket mating surfaces and EGR tubesupply line at the fitting on the EVM. Minimum vac- flange gasket surfaces.uum should be no less than 20 inches. If vacuum is (6) Check for signs of leakage or cracked surfaceslower, check for leaks in vacuum supply line. If leaks at both ends of tube, exhaust manifold and EGRcannot be found, check for low vacuum at vacuum valve.pump. Refer to Group 5, Brake System for proce-dures. INSTALLATION (1) Install a new gasket to EGR valve end of EGR tube.REMOVAL AND INSTALLATION (2) Position EGR tube to engine. (3) Loosely tighten fitting at exhaust manifold endEGR VALVE of tube. (4) Install 2 mounting bolts at EGR valve end ofREMOVAL tube. Tighten bolts to 23 N·m (204 in. lbs.) torque. (1) Remove the rubber hose from turbocharger to (5) Tighten fitting at exhaust manifold end of tube.metal tube. (6) Install hose from turbocharger to metal tube. (2) Disconnect vacuum line at EGR valve vacuumsupply fitting (Fig. 2). ELECTRIC VACUUM MODULATOR (EVM) (3) Loosen the tube fitting at exhaust manifold end The EVM (EGR Duty Cycle Purge Solenoid) isof EGR tube (Fig. 2). mounted to the side of the PDC. (4) Remove the two bolts retaining the EGR tubeto the side of EGR valve (Fig. 2). REMOVAL (5) Remove the two EGR valve mounting bolts (1) Disconnect both cables from battery, negative(Fig. 2) and remove EGR valve. cable first. (6) Discard both of the old EGR mounting gaskets. (2) Remove 2 screws holding PDC to bracket, swing out of way.INSTALLATION (3) Remove nut and clamp holding battery to bat- (1) Clean the intake manifold of any old gasket tery tray (Fig. 4).material. (2) Clean the end of EGR tube of any old gasketmaterial. (3) Position the EGR valve and new gasket to theintake manifold. (4) Install two EGR valve mounting bolts. Do nottighten bolts at this time. (5) Position new gasket between EGR valve andEGR tube. (6) Install two EGR tube bolts. Tighten all fourmounting bolts to 23 N·m (204 in. lbs.). (7) Tighten EGR tube fitting at exhaust manifold. (8) Connect vacuum line to EGR valve. (9) Install the rubber hose from turbocharger tometal tube.EGR TUBE The EGR tube connects the EGR valve to the rearof the exhaust manifold (Fig. 2).REMOVAL (1) Remove rubber hose from turbocharger tometal tube. (2) Remove two EGR tube mounting bolts at EGR Fig. 4 Battery Clampvalve end of tube (Fig. 2). (4) Remove battery from vehicle. (5) Disconnect two vacuum hoses at EVM.
25 - 8 EMISSION CONTROL SYSTEM XJREMOVAL AND INSTALLATION (Continued) (6) Remove mounting screws of EVM. SPECIFICATIONS (7) Remove the EVM to gain access to the EVMelectrical connector. TORQUE CHART—2.5L DIESEL (8) Remove electrical connector at EVM. Description TorqueINSTALLATION (1) Install electrical connector to EVM. EGR Valve Mounting Bolts . . . 23 N·m (204 in. lbs.) (2) Install EVM and tighten mounting screws. EGR Tube Mounting Bolts . . . . 23 N·m (204 in. lbs.) (3) Connect vacuum hoses. EVM (Electric Vacuum Modulator) (4) Install PDC to bracket and tighten mounting Mounting Bolt . . . . . . . . . . . . . 2 N·m (20 in. lbs.)screws. (5) Install battery. (6) Connect battery cables positive first.