Jeep Cherokee (XJ): Diagnosis and testing

Power lock system and remote keyless entry system

On models without the Remote Keyless Entry (RKE) option, proceed directly to the Door Module diagnosis. As a preliminary diagnosis for models with the RKE system, note the power lock system and illuminated entry system operation while you actuate both the Lock and Unlock functions with the power lock switches and the RKE transmitter. Then, proceed as follows:

•  If the entire power lock system fails to function with either the power lock switches or the RKE transmitter, unplug the wire harness connector from the RKE receiver and test the power lock system operation again using the power lock switches. If the power lock system now operates, see the Remote Keyless Entry Receiver diagnosis in this group. If the power lock system still fails to operate, see the Door Module diagnosis in this group.
•  If the power lock system functions with both power lock switches, but not with the RKE transmitter, see the Remote Keyless Entry Transmitter diagnosis in this group.
•  If one power lock motor fails to operate with both of the power lock switches and/or the RKE transmitter, see the Power Lock Motor diagnosis in this group.
•  If the RKE and power lock systems are functioning, but the illuminated entry system fails to operate, see the Remote Keyless Entry Receiver diagnosis in this group.

Door module

If the power lock system is inoperative with either front door power lock switch, test the Passenger Door Module (PDM). If the power lock system is inoperative with only the driver side front door power lock switch, test the Driver Door Module (DDM). For circuit descriptions and diagrams, refer to 8W-61 - Power Door Locks in Group 8W - Wiring Diagrams.

Power lock motor

The only function of the Driver Door Module (DDM) in the power lock system is to provide a Lock or Unlock signal to the power lock system control circuitry contained within the Passenger Door Module (PDM). The DDM signals the PDM by providing a hard-wired ground path through the DDM ground circuit and the driver side power lock switch contacts to the lock request or unlock request terminals of the PDM. The DDM power lock switch function can be tested as follows: (1) Disconnect and isolate the battery negative cable. Remove the driver side front door trim panel and unplug the 12-way DDM wire harness connector (C-2) from the DDM. Check for continuity between the ground circuit cavity of the 12-way DDM wire harness connector and a good ground. There should be continuity. If OK, go to Step 2. If not OK, repair the open circuit to ground as required.

(2) If the problem being diagnosed is inoperative power lock switch illumination, proceed as follows. If the problem is not power lock switch illumination, go to Step 4. Connect the battery negative cable. Turn the ignition switch to the Accessory or On positions.

Check for battery voltage at both sides of the power window circuit breaker in the junction block. If OK, go to Step 3. If not OK, replace the faulty circuit breaker.

(3) With the ignition switch still in the On or Accessory position, check for battery voltage at the fused ignition switch output circuit cavity of the 12-way DDM wire harness connector. If OK, replace the faulty DDM. If not OK, repair the open circuit to the junction block as required.

(4) Test the power lock switch continuity through the DDM 12-way wire harness connector receptacle.

See the DDM Power Lock Switch Continuity chart (Fig. 1) to determine if the continuity is correct in both the Lock and Unlock switch positions. If OK, repair the lock request circuit and/or the unlock request circuit between the DDM and the PDM as required. If not OK, replace the faulty DDM.

Fig. 1 DDM Power Lock Switch Continuity

PASSENGER DOOR MODULE

The Passenger Door Module (PDM) contains the passenger side front door power lock switch and the power lock system control circuitry. In its role as a power lock switch, it provides the power lock system control circuitry with a ground path through the PDM ground circuit and the driver side power lock switch contacts to indicate a lock request or unlock request.

In its role as the power lock control module, the PDM receives inputs from the battery, the ignition switch, the DDM, the driver door ajar switch, the key-in ignition switch, and the headlamp switch. It also receives a hard-wired input from the RKE receiver, if the vehicle is so equipped. In response to these inputs, the PDM sends the proper outputs to control the power lock motors through its integral power lock and unlock relays. The PDM power lock system functions can be tested as outlined below. If the power lock system operates, but the RKE system lock and/or unlock functions are inoperative, see the diagnosis for the Remote Keyless Entry Transmitter in this group.

(1) Check the fuse in the junction block. If OK, go to Step 2. If not OK, repair the shorted circuit or component as required and replace the faulty fuse.

(2) Disconnect and isolate the battery negative cable. Remove the passenger side front door trim panel and unplug the 8-way PDM wire harness connector (C-1) from the PDM. Check for continuity between the ground circuit cavity of the 8-way PDM wire harness connector and a good ground. There should be continuity. If OK, go to Step 3. If not OK, repair the open circuit to ground as required.

(3) If the problem being diagnosed is inoperative power lock switch illumination, proceed as follows. If the problem is not power lock switch illumination, go to Step 5. Connect the battery negative cable. Turn the ignition switch to the Accessory or On positions.

Check for battery voltage at both sides of the power window circuit breaker in the junction block. If OK, go to Step 4. If not OK, replace the faulty circuit breaker.

(4) With the ignition switch still in the Accessory or On positions, check for battery voltage at the fused ignition switch output circuit cavity of the 8-way PDM wire harness connector. If OK, replace the faulty PDM. If not OK, repair the open circuit to the junction block as required.

(5) If the problem being diagnosed is an inoperative door lock inhibit feature or a power lock system that responds to an Unlock command, but not a Lock command, proceed as follows. Otherwise, go to Step 7. With the driver side front door closed, check for continuity between the door ajar/key-in circuit cavity of the 8-way PDM wire harness connector and a good ground. There should be no continuity. If OK, go to Step 6. If not OK, repair the shorted door ajar and/or key-in ignition circuits as required. Refer to Group 8U - Chime/Buzzer Warning Systems for more information.

(6) Open the driver side front door with the key in the ignition switch or with the headlamp switch in the On position. Check for continuity between the door ajar/key-in circuit cavity of the 8-way PDM wire harness connector and a good ground. There should be continuity. If OK, go to Step 8. If not OK, repair the open door ajar and/or key-in ignition circuits as required. Refer to Group 8U - Chime/Buzzer Warning Systems for more information.

(7) Connect the battery negative cable. Check for battery voltage at the fused B(+) circuit cavity of the 8-way PDM wire harness connector. If OK, go to Step 8. If not OK, repair the open circuit to the fuse in the junction block as required.

(8) Test the PDM power lock switch continuity through the two PDM wire harness connector receptacles.

See the PDM Power Lock Switch Continuity chart (Fig. 2) to determine if the continuity is correct in both the Lock and Unlock switch positions. If OK, see the diagnosis for Power Lock Motors in this group. If not OK, replace the faulty PDM.

Remote keyless entry transmitter

Before you proceed with this diagnosis, confirm proper power door lock switch operation. See Door Module in this group for the diagnostic procedures.

Remember, the Passenger Door Module (PDM) circuitry controls the output to each of the power lock motors. For circuit descriptions and diagrams, refer to 8W-61 - Power Door Locks in Group 8W - Wiring Diagrams.

Fig. 2 PDM Power Lock Switch Continuity

(1) Check each power lock motor for correct operation while moving the power lock switch to both the Lock and Unlock positions. If all of the power lock motors are inoperative, go to Step 2. If one power lock motor is inoperative, go to Step 3.

(2) If all of the power lock motors are inoperative, the problem may be caused by one shorted motor.

Unplugging a shorted power lock motor from the power lock circuit will allow the good power lock motor to operate. Unplug each power lock motor wire harness connector, one at a time, and recheck both the lock and unlock functions by operating the power lock switch. If all of the power lock motors are still inoperative after the above test, check for a short or open circuit between the power lock motors and the PDM. If unplugging one power lock motor causes the other motors to become functional, go to Step 3 to test the unplugged motor.

(3) Once it is determined which power lock motor is inoperative, that motor can be tested as follows.

Unplug the wire harness connector at the inoperative power lock motor. Apply 12 volts to the motor terminals to check its operation in one direction. Reverse the polarity to check the operation in the other direction.

If OK, repair the short or open circuits between the power lock motor and the PDM as required. If not OK, replace the faulty power lock motor.

REMOTE KEYLESS ENTRY TRANSMITTER

(1) Replace the Remote Keyless Entry (RKE) transmitter batteries. See Remote Keyless Entry Transmitter Battery Replacement in this group for the procedures. Test each of the transmitter functions.

If OK, discard the faulty batteries. If not OK, go to Step 2.

(2) Perform the Remote Keyless Entry Transmitter Programming procedure with the suspect transmitter and another known good transmitter. Use a DRB scan tool, as described in the proper Diagnostic Procedures manual.

(3) Test the RKE system operation with both transmitters. If both transmitters fail to operate the power lock system, see the diagnosis for the Remote Keyless Entry Receiver in this group. If the known good transmitter operates the power locks and the suspect transmitter does not, replace the faulty transmitter.

NOTE: Be certain to perform the Remote Keyless Entry Transmitter Programming procedure again following this test. This procedure will erase the access code of the test transmitter from the RKE receiver.

Remote keyless entry receiver

If the problem being diagnosed is an inoperative Remote Keyless Entry (RKE) horn chirp feature, be certain that the horn chirp feature has not been disabled.

See Remote Keyless Entry Receiver Programming in this group for the procedures. Also be certain that the vehicle horn system is operational. Refer to Group 8G - Horn Systems for more information.

If the problem being diagnosed is an inoperative RKE illuminated entry system, be certain that the interior courtesy lamp system is operational. Refer to Group 8L - Lamps for more information.

Before you proceed with diagnosis of the RKE receiver, see the diagnosis for Remote Keyless Entry Transmitter in this group. For circuit descriptions and diagrams, refer to 8W-61 - Power Door Locks in Group 8W - Wiring Diagrams.

(1) Check the fuses in the Power Distribution Center (PDC) and the junction block. If OK, go to Step 2.

If not OK, repair the shorted circuit or component as required and replace the faulty fuse.

(2) Disconnect and isolate the battery negative cable. Remove the Remote Keyless Entry (RKE) receiver from the headliner. Unplug the wire harness connector from the RKE receiver.

(3) Check the wire harness connector and the receptacle in the RKE receiver for loose, corroded, or damaged terminals and pins. If OK, go to Step 4. If not OK, repair as required.

(4) Check for continuity between each of the two ground circuit cavities of the RKE receiver wire harness connector and a good ground. In each case, there should be continuity. If OK, go to Step 5. If not OK, repair the circuit to ground as required.

(5) Connect the battery negative cable. Check for battery voltage at each of the two fused B(+) circuit cavities of the RKE receiver wire harness connector.

If OK, go to Step 6. If not OK, repair the open circuit to the PDC or the junction block as required.

(6) If the problem being diagnosed involves only the RKE horn chirp feature, go to Step 10. If the problem being diagnosed involves only the RKE illuminated entry feature, go to Step 9. If the problem being diagnosed involves only the RKE power lock feature, go to Step 7.

(7) Disconnect and isolate the battery negative cable. Unplug the 8-way Passenger Door Module (PDM) wire harness connector. Check for continuity between the lock request circuit cavity of the RKE receiver wire harness connector and a good ground.

Repeat the test between the unlock request circuit cavity of the RKE receiver wire harness connector and a good ground. In each case, there should be no continuity. If OK, go to Step 8. If not OK, repair the shorted circuit as required.

(8) Check for continuity between the lock request circuit cavities of the RKE receiver wire harness connector and the 8-way PDM wire harness connector.

Repeat the test between the unlock request circuit cavities of the RKE receiver wire harness connector and the 8-way PDM wire harness connector. In each case, there should be continuity. If OK, replace the faulty RKE receiver. If not OK, repair the open circuit as required.

(9) Check for continuity between the door ajar circuit cavity of the RKE receiver wire harness connector and a good ground with the driver door closed.

There should be no continuity until the driver door is opened. If OK, replace the faulty RKE receiver. If not OK, repair the circuit or replace the faulty driver door ajar switch as required.

(10) Unplug the horn relay from the junction block. Check for continuity between the horn relay output circuit cavity of the RKE receiver wire harness connector and a good ground. There should be no continuity. If OK, go to Step 11. If not OK, repair the short circuit to the horn relay as required.

(11) Check for continuity between the horn relay output circuit cavity of the RKE receiver wire harness connector and the junction block cavity for the horn relay coil ground terminal (85). There should be continuity. If OK, replace the faulty RKE receiver. If not OK, repair the open circuit to the junction block as required.