Part 2 of 2
INSTRUMENT CLUSTERThe instrument cluster for Jeep Cherokee (XJ) is available for two different versions: base with two gauges and premium with six gauges. The gauges are positioned with information received by the cluster over the CCD bus from the PCM. Some of the warning lamps are hardwired and some are controlled by the cluster using CCD bus information. The vehicle chime function is contained on the cluster circuit board, as well as the timer for the rear window defogger. There is a self-test available for the cluster that will actuate all the gauges and place them at their calibration points. The test will not run if the cluster sees engine RPM or vehicle speed. This test will light all CCD controlled lamps for verification of lamp operation. It also forces the odometer Vacuum Fluorescent (VF) display to count up from all zero's through all nine's. The self-test routine can be entered by pushing and holding the trip reset button while rotating the ignition key from the "off' to the "on" position, release the button after the test starts.
The VF display is also capable of displaying PCM DTC's. This feature is accessed the same as in previous years by turning they key from "off' to "run" three times and staying in position.
The instrument cluster will provide bus bias and termination and the PCM controller provides a second termination. If cluster is disconnected, the bus will not be biased.
The cluster will be serviced as an assembly. There will be limited parts available: bulbs and sockets, the front lens, the trip odometer stem cover and the hood and rear cover assembly. No internal parts of the lowline or highline cluster will be serviced.
Normal Operation: At key "ON", the cluster will light the low fuel, oil pressure, temperature battery, seat belt, check gauges and airbag lamps. The check engine, ABS, and SKIM lamps are bulb tested by their system modules. As the key is turned farther toward the start position, the brake warning lamp will illuminate. The Vacuum Fluorescent (VF) display will indicate the mileage stored inside the cluster. If there is a bus failure and the cluster cannot receive distance pulses from the engine controller, the cluster will display the last mileage stored until the ignition key is turned off. If the cluster is receiving bus messages, but is unable to display odometer information because of an internal failure, the odometer display dashes. VF dimming is handled by the potentiometer that controls instrumentation illumination.
Heated Rear Window Defogger
The timing circuit for the rear window defogger is contained in the cluster. The operation is as follows: With the ignition ON, the first push of the defogger button Will start a 10-minute timer. After 10 minutes have elapsed, the defogger Will be turned OFF. If the button is pushed a second time during the same ignition cycle, the timer will turn the defogger ON for five minutes. Every consecutive push will operate the defogger for five minutes. When the defogger is ON, it can be turned OFF with a second push of the defogger button.
Chime
The chime function is a 1000 Hz tone within the cluster. The cluster will not generate more than one chime per condition in the same ignition cycle. If a problem occurs that requires a second chime while the first one is currently being generated, the second chime request will be ignored. The chime will sound for the following conditions:
Headlamps ON and driver's door open
Seat Belt Warning - Six seconds after key ON
Key in Ignition Warning Driver's front door open with key in ignition
Engine Temp High - When gauges enter red zone Low Fuel - When fuel reaches 1/8 of a tank
When overhead console is reset
SKIM key successfully programmed
Lamps (Hardwired)
The following lamps are hardwired to the cluster and are not part of the self-test:
Brake Warning (Red) - bulb test performed when the ignition switch is turned to the crank position
Full Time 4WD
Part Time 4WD High Beam
Left Turn Signal
Liftgate Ajar
The following lamps are bulb tested at ignition on by the appropriate system module.
ABS (Amber)
Check engine
SKIM
Lamps (CCD)
The following lamps are controlled by the cluster via CCD messages. They are bulb tested (actuated) during the self-test procedure.
Airbag
Cruise Control
Low Fuel Warning
Low Washer Fluid
Upshift (If equipped)
Seat Belt
Sentry Key Immobilizer
Engine Temp (If equipped)
Battery (If equipped)
Low Oil Pressure Warning (If equipped)
The lowline cluster does not contain a check gauges telltale.
NOTE: THE SEAT BELT AND LOW WASHER FLUID SWITCHES ARE HARDWIRED TO THE CLUSTER. THE CLUSTER THEN DECIDES IF THE LAMP SHOULD ILLUMINATE BASED ON THE HARDWIRED INPUT.
DIAGNOSTICS
Gauges
The Mechanical Instrument Cluster (MIC) will not store any DTCs. Because the Powertrain Control Module (PCM) gathers all the gauge information and sends it to the cluster via the bus, it is the PCM's responsibility to monitor these inputs and store DTCs for them. For this reason, the first item to be checked regarding a gauge problem (except oil pressure) should be the PCM for any DTCs relating to the gauge in question.
There are DTCs associated with all the gauges except for the oil pressure gauge. When diagnosing gauges, the input that is used for the gauge message (fuel level sender, for example) must be valid. Because of OBD II requirements, most of the information used for monitoring the OBD II system is the same information used by the controller to formulate the gauge bus messages. OBD II requirements state the fuel level sender must be checked for rationality. This includes determining if the sending unit voltage is too high or too low, or if the voltage has not changed over time. If the PCM has determined the sender information is not valid, it will set the DTC. The presence or absence of the fuel level sending code in the PCM is an important factor to determine whether a fuel gauge problem is in the sending unit or the cluster.
This same situation is used in all cluster diagnostics related to gauge operation with the exception of the oil pressure gauge. OBD II requirements do not include oil pressure monitoring. Therefore, oil pressure diagnostics would dictate that a mechanical oil pressure gauge be attached to the engine for absolute verification of oil pressure readings.
Hardwired Lamps
The cluster contains several hardwired lamps described earlier. These lamps are set up in two configurations: The lamp is supplied power by the cluster and the ground is supplied by the circuit being monitored, or the lamp is supplied with a ground in the cluster and power comes from a module or other device. Verification of the bulb filament may be required in all cases of an inoperative lamp. This will require removal of the cluster and bulb in question.
CCD Controlled Lamps
The cluster contains several CCD controlled lamps as described earlier. These lamps are part of the diagnostic self-test. When entering the self-test mode, operation of these lamps can be observed. If the bulb fails to operate during the self-test and the bulb filament is good, the cluster assembly will need to be replaced.
REMOTE KEYLESS ENTRY (RKE)
The Remote Keyless Entry (RKE) module is in the overhead console or in the dome lamp assembly. It operates on a RF signal, which makes it less dependent on the aiming of the transmitter. When an unlock signal is received (from a transmitter), the module will ground the unlock control circuit, therefore actuating the passenger door module and at the same time grounding the courtesy lamps driver circuit, actuating the illuminated entry. The RKE module is capable of retaining four individual vehicle access codes (four transmitters). This system incorporates a rolling code feature. A horn chirp feature is also part of this system and is customer programmable.
The RKE module has some DRBIII (R) functions, actuators, read switch states, and RF signal status. The Door Lock, Door Unlock, Horn and Illuminated Entry lights cab be actuated. The horn and illuminated entry activation time is adjustable using the DRBIII (R). The DRBIII (R) will read the switch status of the door lock switch and door unlock switch (opened/closed), the RF signal (valid/invalid) RF checksum, Programmed/Non-programmed RF transmitter, and the In-Sync/Out-of-Sync transmitter. The D.B. can also turn the horn chirp and illuminated entry ON and OFF.
The XJ will be shipped with the horn chirp enabled. It can be deactivated manually using the following procedure: Press and hold the LOCK button on the transmitter for 5 - 10 seconds, and then while the LOCK button is pressed, press and release the UNLOCK button. The horn chirp feature can be reactivated by repeating the procedure.
Programming An RKE Transmitter
Programming a transmitter can be accomplished using either the DRBIII (R) or the MDS machine. Using the DRBIII (R) select "Theft Alarm" (even though "Vehicle Theft Security System" is not available for this vehicle) then "Miscellaneous" then "Programming RKE". Select a position (1 - 4). The locks will cycle to verify you are in programming mode. Press the unlock button on the transmitter. The locks will cycle again to verify programming has taken place. When you program to a position, that code will overwrite the code that was in that position and because you have no way of knowing if a valid code was there or not, it is recommended that whenever it is necessary to program a transmitter, all transmitters that are to be used with that vehicle should be programmed at that time. The 1999 XJ will have 2 RKE transmitter.
Synchronization (Rolling Code) Button Transmitters
The transmitter will go out of synchronization if the button is pressed more than 128 times outside of the range of the receiver In other words the transmitter will not unlock the doors. The transmitter will go out of synchronization if the batteries are removed and replaced. To synchronize the code of the particular transmitter with the receiver, press and hold the "lock" button while within the receiver range.
SENTRY KEY IMMOBILIZER
The SKIS is an immobilizer system designed to prevent unauthorized vehicle operation. The system consists of a Sentry Key Immobilizer Module (SKIM) and ignition key(s) called Sentry Key(s) which are equipped with a transponder chip. The SKIM communicates over the Chrysler Collision Detection Multiplex System (CCD) bus network to the Powertrain Control Module (PCM), and/or the DRB scan tool.
When the ignition is turned to the Run/Start position, the SKIM produces a Radio Frequency (RF) signal via an antenna which is located around the ignition lock cylinder. The RF powers up the transponder chip inside the Sentry Key. The transponder chip then emits a coded signal that is received by the SKIM antenna. If this coded signal is valid, the SKIM sends a "VALID KEY" message to the PCM. If the first transponder signal is not valid, the SKIM will attempt four more times to receive a correct transponder signal. If a valid signal is not received, the SKIM stores a diagnostic trouble code and send a "INVALID KEY" message to the PCM. Then the PCM will only allow the engine to start for two seconds then stall. This start and stall will be allowed up to six times, after which the PCM will disable the starter relay.
The SKIS includes two valid Sentry Keys from the factory. If the customer wishes, additional uncoded Sentry Key blanks are available. These blank keys must be cut to match a valid key, but the engine Will not start unless the transponder chip inside the blank key is programmed to that particular vehicle.
The Sentry Key Immobilizer System (SKIS) can be programmed to recognize a total of eight keys. For programming
The SKIM sends messages to the Instrument Cluster over the CCD bus to control the SKIM indicator lamp. The SKIM sends a message to the cluster for about three seconds when the ignition is turned to the Run/Start position as a bulb test. If the indicator lamp comes on and stays on after the bulb test, it indicates that the SKIM has detected a system malfunction and/or that SKIS has become inoperative. If an invalid key is detected in the ignition key cylinder with the ignition switch in the Run/Start position, or when the SKIM has entered its customer key programming mode, the SKIM will flash the SKIM indicator lamp on and off.
Sentry Key Immobilizer Trouble Codes
Typically, modules have Diagnostic Trouble Codes that are referred to as either active or stored. In the case of the Sentry Key Immobilizer Module, however, all codes are stored codes. The two various types of stored codes in the SKIM can be considered to be either current or pre-existing codes. If more than one code exists, diagnostic priority should be given to the active code(s). Record the DTC's before attempting to erase the DTC's. Active codes cannot be erased. Cycle the ignition and wait 90 seconds before reading DTC's again. If there are no active DTC's then refer to the pre-existing DTC's recorded in the previous step. A current code indicates a malfunction that is CURRENT at the time of vehicle service. A pre-existing code indicates the malfunction is not currently present. If a malfunction is not detected after 80 ignition cycles, the code will automatically be erased.
Sentry Key Immobilizer Module Trouble Codes
Antenna Failure
EEPROM Failure
Internal SKIM Failure
PCM Status Failure
Rolling Code Failure
Serial Link External Failure
Serial Link Internal Failure
Transponder Communication Failure
Transponder (Cyclic Redundancy Check) CRC Failure
Transponder ID Mismatched
Transponder Response Mismatch VIN Mismatch
Sentry Key Immobilizer Module Replacement And System Initialization Process
IMPORTANT NOTE: IF THE POWERTRAIN CONTROL MODULE HAS BEEN CHANGED AND THE CORRECT VIN AND MILEAGE HAVE NOT BEEN PROGRAMMED, A DTC WILL BE SET IN THE AIRBAG MODULE. IN ADDITION, IF THE VEHICLE IS EQUIPPED WITH A SENTRY KEY IMMOBILIZER MODULE (SKIM), SECRET KEY DATA MUST BE UPDATED TO ENABLE STARTING.
The Sentry Key Immobilizer Module (SKIM) Replacement and System Initialization Process can be summarized by the following:
1. Obtain the vehicle's unique PIN number assigned to its original SKIM module from either the vehicle's invoice or from Chrysler's Customer Center.
2. With the DRB, select "Theft Alarm," "Skim," "Miscellaneous." Select "SKIM Module Replaced" and the DRB will prompt you through the following steps.
3. Program the unique 4 digit PIN number into the SKIM's memory.
4. Program the vehicle's VIN number into the SKIM's memory.
5. Program the county code into the SKIM's memory (U.S.).
6. Transfer the vehicle's unique Secret Key data from the PCM. This process will require the SKIM module to be in secured access mode. The PIN number must be entered into the DRB before the SKIM will enter secured access mode. Once secured access mode is active, the SKIM will remain in that mode for 60 seconds.
7. Program all customer keys into the SKIM's memory. This requires that the SKIM be in secured access mode. The SKIM module will immediately exit secured access mode after each key is programmed. Note: Secured access mode is not required to query the programmed status of the key.
NOTE:
- IF A PCM IS REPLACED, THE UNIQUE SECRET KEY DATA MUST BE TRANSFERRED FROM THE SKIM MODULE TO THE PCM. THIS PROCEDURE REQUIRES THE SKIM TO BE PLACED IN SECURED ACCESS MODE USING THE FOUR DIGIT PIN CODE.
- IF THREE ATTEMPTS ARE MADE TO ENTER SECURED ACCESS MODE USING AN INCORRECT PIN, SECURED ACCESS MODE WILL BE LOCKED OUT FOR ONE HOUR. TO EXIT THIS LOCK OUT MODE, LEAVE THE IGNITION SWITCH IN THE RUN POSITION CONTINUOUSLY FOR ONE HOUR. (ENSURE ALL ACCESSORIES ARE TURNED OFF. ALSO MONITOR THE BATTERY STATE AND CONNECT A BATTERY CHARGER IF NECESSARY).
To program Sentry Keys using the "customer programming" method, which requires two valid Sentry Keys.
Programming Blank Sentry Keys With The DRB
When programming a blank Sentry Key transponder, the key blank must first be cut to match the ignition lock cylinder. It will also be necessary to enter the vehicle's 4-digit PIN code into the DRB to enter the SKIM's secured access mode.
NOTE: ONCE A SENTRY KEY IS PROGRAMMED TO A PARTICULAR VEHICLE IT CANNOT BE TRANSFERRED TO ANOTHER VEHICLE.
Insert the blank key into the ignition and turn it to the Run/Start position. Using the DRB select "Theft Alarm", then "SKIM", then "Miscellaneous". Select "Program New Key." Enter the 4-digit PIN code using the DRB. When programming is completed, the SKIM will exit secured access mode and display the status of the key. The different status messages are (programming successful, learned key in ignition, maximum key limit exceeded, programming not attempted or programming failed).
"Programming Successful" is displayed if SKIM Sentry Key programming succeeds.
"Learned Key in Ignition" is displayed if the key in the ignition has already been programmed into that vehicle's SKIM.
"8 Keys Already Learned (At The Maximum) Programming Not Done" is displayed if eight keys have already been programmed into the SKIM. In this case, if a new key needs to be added due to a lost or defective key, the "Erase All Keys" function (requires entering secured access mode) has to be performed. Then the customer's seven keys plus the new key MUST be reprogrammed into the SKIM.
"Programming Key Failed" is displayed if further diagnosis is required.
To learn additional keys, turn the ignition off, remove the learned key, and insert the next new blank key. Turn ignition to the Run position and re-enter the secured access mode function and repeat the "Program New Key" procedure outlined above.
VEHICLE COMMUNICATION
The Chrysler Collision Detection multiplex system (CCD bus) consists of a twisted pair of wires. These wires run from one module to another. They receive and deliver coded information between the modules. The information is coded to identify the message, as well as the importance of the message. When there are multiple messages trying to access the CCD bus at one time, the code determines the message that has higher priority and is then allowed to access the bus first.
The two wires of the twisted pair that make up the CCD multiplex system are called "bus+" (bus plus) and "bus-" (bus minus) respectively. Each wire has a measurable voltage level of roughly 2.5 volts. In order to maintain the 2.5 volts on each line and provide a means of transportation for the coded messages, there is a "voltage divider network." This network consists of the Mechanical Instrument Cluster (MIC) that supplies both bias and termination and the PCM that provides a second termination. Bias is the part of the voltage divider network that places both bus+ and bus- at 2.5 volts. Termination in the circuitry is required to complete the voltage divider network and it also provides some electromagnetic protection for the bus.
NOTE: COMMUNICATION OVER THE BUS IS ESSENTIAL TO THE PROPER OPERATION OF SOME VEHICLE SYSTEMS, ON BOARD DIAGNOSTIC (OBD) SYSTEMS AND COMMUNICATION WITH THE DRB. PROBLEMS WITH THE OPERATION OF THE BUS OR DRB MUST BE CORRECTED BEFORE PROCEEDING WITH DIAGNOSTIC TESTING. IF THERE IS A PROBLEM, REFER TO THE VEHICLE COMMUNICATIONS.
CCD Bus Failure Messages
Short to Battery - Either or both of the bus wires are shorted to the battery potential.
Short to 5 Volts -Either or both of the bus wires are shorted to a 5-Volt potential.
Short to Ground - Either or both of the bus wires are shorted to to ground or a specific ground may be open.
Bus (+) or Bus (-) Shorted Together - The two bus wires are shorted together.
Bus Bias Level Too Low - Either or both of the bus wire potentials are significantly below their normal 2.5 volts.
Bus Bias Level Too High - Either or both of the bus wire potentials are significantly above their normal 2.5 volts.
No Termination - The bus system has lost connection with all of its terminators. The Instrument Cluster (MIC) and Power Train Controller (PCM) supplies termination for the 1997 Jeep Cherokee.
No Bus Bias - The bus system has lost connection with all modules that provide bias. The Instrument Cluster (MIC) provides the CCD bus bias for the 1997 Jeep Cherokee.
Not Receiving Bus Messages Correctly - The DRB cannot communicate over the bus and does not know why.