Power Seat Systems — 1998 Jeep Grand Cherokee ZJ Export Service Manual
Pages 511–518 · 8 pages · 8 words repaired
memory functions and features. The MSM contains a central processing unit and interfaces with other modules in the vehicle on the Chrysler Collision Detection (CCD) data bus network.
The MSM receives hard-wired inputs from the power seat switch, the power lumbar switch, and the potentiometers on each of the driver side power seat motors. The MSM receives messages on the CCD data bus from the Driver Door Module (DDM) (memory set/select switch status), the Powertrain Control Module (PCM) (vehicle speed status), and the Body Control Module (seat belt switch status). The programming in the MSM allows it to process the information from these inputs and send control outputs to each of the driver side power seat motors. The MSM will prevent the seat memory function from being initiated if the driver side seat belt is buckled, or if the vehicle is moving.
For diagnosis of the MSM or the CCD data bus, a DRB scan tool and the proper Diagnostic Procedures manual are recommended. The MSM cannot be repaired and, if faulty or damaged, it must be replaced.
POWER SEAT SWITCH
The power seat can be adjusted in eight different ways using the power seat switch. The switch is located on the lower outboard side of the seat cushion on the seat cushion side shield. Refer to the owner's manual for more information on the power seat switch functions and the seat adjusting procedures.
The individual switches in the power seat switch module cannot be repaired. If one switch is damaged or faulty, the entire power seat switch module must be replaced.
POWER LUMBAR SWITCH
The power lumbar adjuster on each front seat can be moved in or out electrically by operating the single two-way switch mounted near the front of the outboard seat cushion side shield.
The power lumbar switches cannot be repaired and, if faulty or damaged, they must be replaced.
POWER SEAT ADJUSTER AND MOTORS
There are three reversible motors that operate the power seat adjuster. The motors are connected to worm-drive gearboxes that move the seat adjuster through a combination of screw-type drive units.
The front and rear of a seat are operated by different motors. They can be raised or lowered independently of each other. When the center of the seat switch knob is pushed in the Up or Down direction, both the front and rear motors operate in unison, moving the entire seat up or down. The forward-rearward motor is operated by pushing the seat switch knob in the Forward or Rearward direction.
When a power seat switch is actuated, a battery feed and a ground path are applied through the switch contacts to the motor(s). The motor(s) and drive unit(s) operate to move the seat in the selected direction until the switch is released, or until the travel limit of the power seat adjuster is reached. When the switch is moved in the opposite direction, the battery feed and ground path to the motor(s) are reversed through the switch contacts. This causes the motor to run in the opposite direction.
Each motor contains a self-resetting circuit breaker to protect it from overload. Consecutive or frequent resetting of the circuit breakers must not be allowed to continue, or the motors may be damaged. Make the necessary repairs. The motors used on models with the optional memory system also have a position potentiometer included in the motor assembly.
The power seat adjuster and motors cannot be repaired, and are serviced only as a complete unit. If any component in this unit is faulty or damaged, the entire power seat adjuster and motors assembly must be replaced.
POWER RECLINER ADJUSTER AND MOTOR
The power recliner adjuster uses a reversible motor to operate the seat back recliner adjuster. The motor is connected to a gearbox that moves the recliner adjuster through a screw-type drive unit.
When the power recliner switch is actuated, a battery feed and a ground path are applied through the switch contacts to the motor. The motor operates to move the seat back in the selected direction until the switch is released, or until the travel limit of the power recliner adjuster is reached. When the switch is moved in the opposite direction, the battery feed and ground path to the motor are reversed through the switch contacts. This causes the motor to run in the opposite direction.
The motor contains a self-resetting circuit breaker to protect it from overload. Consecutive or frequent resetting of the circuit breaker must not be allowed to continue, or the motor may be damaged. Make the necessary repairs. The motor used on models with the optional memory system also has a position potentiometer included in the motor assembly.
The power recliner adjuster and motor cannot be repaired, and is serviced only as a complete unit. If any component in this unit is faulty or damaged, the entire power recliner adjuster and motor assembly must be replaced.
POWER LUMBAR ADJUSTER AND MOTOR
There is a reversible motor that operates the power lumbar adjuster. The motor is connected to a wormdrive gearbox that moves the lumbar adjuster mechanism through a cable and lever-type actuator unit.
When the power lumbar switch is actuated, a battery feed and a ground path are applied through the switch contacts to the motor. The motor operates to move the lumbar adjuster mechanism in the selected direction until the switch is released, or until the travel limit of the lumbar adjuster is reached. When the switch is moved in the opposite direction, the battery feed and ground path to the motor are reversed through the switch contacts. This causes the motor to run in the opposite direction.
The motor contains a self-resetting circuit breaker to protect it from overload. Consecutive or frequent resetting of the circuit breaker must not be allowed to continue, or the motor may be damaged. Make the necessary repairs. The motor used on models with the optional memory system also has a position potentiometer included in the motor assembly.
The power lumbar adjuster and motor cannot be repaired, and are serviced only as a complete unit with the seat back frame. If any component in this unit is damaged or is faulty, the entire power lumbar seat back frame assembly must be replaced.
CIRCUIT BREAKER
An automatic resetting circuit breaker in the junction block is used to protect the power seat system circuit. The circuit breaker can protect the system from a short circuit, or from an overload condition caused by an obstructed or stuck seat adjuster.
The circuit breaker cannot be repaired and, if faulty or damaged, it must be replaced.
DIAGNOSIS AND TESTING
POWER SEAT SYSTEM
Before any testing of the power seat system is attempted, the battery should be fully-charged and all wire harness connections and pins cleaned and tightened to ensure proper continuity and grounds. For circuit descriptions and diagrams, refer to 8W-63 - Power Seat in Group 8W - Wiring Diagrams.
With the dome lamp on, apply the power seat switch in the direction of the failure. If the dome lamp dims, the seat may be jamming. Check under and behind the seat for binding or obstructions. If the dome lamp does not dim, proceed with testing of the individual components and circuits.
CIRCUIT BREAKER
For circuit descriptions and diagrams, refer to 8W-63 - Power Seat in Group 8W - Wiring Diagrams.
(1) Locate the correct circuit breaker in the junction block. Pull out the circuit breaker slightly, but be certain that the circuit breaker terminals still contact the terminals in the junction block cavities.
(2) Connect the negative lead of a 12-volt DC voltmeter to a good ground.
(3) With the voltmeter positive lead, check both terminals of the circuit breaker for battery voltage.
If only one terminal has battery voltage, the circuit minal has battery voltage, repair'the open circuit from the Power Distribution Center (PDC) as required.
POWER SEAT SWITCH
For circuit descriptions and diagrams, refer to 8W-63 - Power Seat in Group 8W - Wiring Diagrams.
(1)
Disconnect and isolate the battery negative cable.
Remove the power seat switch from the power seat.
(2) Use an ohmmeter to test the continuity of the power seat switches in each position. See the Power Seat Switch Continuity chart (Fig. 1). If OK, see the diagnosis for the Power Seat Adjuster and Motors or Power Recliner Adjuster and Motor, as required. If not OK, replace the faulty power seat switch module.
POWER LUMBAR SWITCH
For circuit descriptions and diagrams, refer to 8W-63 - Power Seat in Group 8W - Wiring Diagrams.
(1) Disconnect and isolate the battery negative cable. Remove the power lumbar switch from the power seat.
(2) Use an ohmmeter to test the continuity of the power lumbar switch in each switch position. See the Power Lumbar Switch Continuity chart (Fig. 2). If OK, see the diagnosis for the Power Lumbar Adjuster and Motor. If not OK, replace the faulty power lumbar switch.
POWER SEAT ADJUSTER AND MOTORS
The tests below apply to a power seat system without the memory system option. For testing of the power seats with the memory system, refer to the proper Diagnostic Procedures manual. For circuit descriptions and diagrams, refer to 8W-63 - Power Seat in Group 8W - Wiring Diagrams.
Operate the power seat switch to move all three seat motors in each direction. The seat should move in each of the selected directions. If the power seat adjuster fails to operate in only one direction, move the adjuster a short distance in the opposite direction and test again to be certain that the adjuster is not at its travel limit. If the power seat adjuster still fails to operate in only one direction, see the diagnosis for the Power Seat Switch in this group. If the power seat adjuster fails to operate in more than one direction, proceed as follows:
(1) Test the circuit breaker in the junction block as described in this group. If OK, go to Step 2. If not OK, replace the faulty circuit breaker.
(2) Remove the power seat switch from the seat. Check for battery voltage at the fused B(+) circuit cavity of the power seat switch wire harness connector. If OK, go to Step 3. If not OK, repair the open circuit to the junction block as required.
(3) Check for continuity between the ground circuit cavity of the power seat switch wire harness connector and a good ground. There should be continuity. If OK, go to Step 4. If not OK, repair the open circuit to ground as required.
(4) Test the power seat switch as described in this group. If the switch tests OK, check the wire harness to the inoperative power seat motor(s) between the
power seat switch and the motor for shorts or opens. If the circuits check OK, replace the faulty power seat adjuster and motors assembly. If the circuits are not OK, repair the wire harness as required.
POWER RECLINER ADJUSTER AND MOTOR
The tests below apply to a power seat system without the memory system option. For testing of the power seats with the memory system, refer to the proper Diagnostic Procedures manual. For circuit descriptions and diagrams, refer to 8W-63 - Power Seat in Group 8W - Wiring Diagrams.
Operate the power seat switch to move the power recliner adjuster in each direction. The recliner adjuster should move in both directions. If the power recliner adjuster fails to operate in only one direction, move the adjuster a short distance in the opposite direction and test again to be certain that the adjuster is not at its travel limit. If the power recliner adjuster still fails to operate in only one direction, see the diagnosis for the Power Seat Switch in this group. If the power recliner adjuster fails to operate in either direction, proceed as follows:
(1) Test the circuit breaker in the junction block as described in this group. If OK, go to Step 2. If not OK, replace the faulty circuit breaker.
(2) Remove the power seat switch from the seat. Check for battery voltage at the fused B(+) circuit cavity of the power seat switch wire harness connector. If OK, go to Step 3. If not OK, repair the open circuit to the junction block as required.
(3) Check for continuity between the ground circuit cavity of the power seat switch wire harness connector and a good ground. There should be continuity. If OK, go to Step 4. If not OK, repair the open circuit to ground as required.
(4) Test the power seat switch as described in this group. If the switch tests OK, check the wire harness for the power recliner adjuster motor between the power seat switch and the motor for shorts or opens. If the circuits check OK, replace the faulty power recliner adjuster and motor assembly. If the circuits are not OK, repair the wire harness as required.
POWER LUMBAR ADJUSTER AND MOTOR
The tests below apply to a power seat system without the memory system option. For testing of the power seats with the memory system, refer to the proper Diagnostic Procedures manual. For circuit descriptions and diagrams, refer to 8W-63 - Power Seat in Group 8W - Wiring Diagrams.
Operate the power lumbar switch to move the power lumbar adjuster in each direction. The lumbar adjuster should move in both directions. If the power lumbar adjuster fails to operate in only one direction, move the adjuster a short distance in the opposite direction and test again to be certain that the adjuster is not at its travel limit. If the power lumbar adjuster still fails to operate in only one direction, see the diagnosis for the Power Lumbar Switch in this group. If the power lumbar adjuster fails to operate in either direction, proceed as follows:
(1) Test the circuit breaker in the junction block as described in this group. If OK, go to Step 2. If not OK, replace the faulty circuit breaker.
(2) Remove the power lumbar switch from the seat. Check for battery voltage at the fused B(+) circuit cavity of the power lumbar switch wire harness connector. If OK, go to Step 3. If not OK, repair the open circuit to the junction block as required.
(3) Check for continuity between the ground circuit cavity of the power lumbar switch wire harness connector and a good ground. There should be continuity. If OK, go to Step 4. If not OK, repair the open circuit to ground as required.
(4) Test the power lumbar switch as described in this group. If the switch tests OK, check the wire harness for the power lumbar adjuster motor between the power lumbar switch and the motor for shorts or opens. If the circuits check OK, replace the faulty power lumbar adjuster and motor, which are serviced with the seat back frame assembly. If the circuits are not OK, repair the wire harness as required.
REMOVAL AND INSTALLATION
POWER SEAT SWITCH
(1) Disconnect and isolate the battery negative cable.
(2) Using a trim stick or another suitable wide flat-bladed tool, gently pry the power seat and power recliner switch knobs off of the switch stems.
(3) Remove the three screws that secure the seat cushion side shield to the outboard seat cushion frame.
(4) Pull the seat cushion side shield away from the seat cushion frame far enough to access the power seat switch and power lumbar switch wire harness connectors.
(5) Unplug the wire harness connectors from the power seat and power lumbar switches.
(6) Remove the seat cushion side shield from the vehicle.
(7) Remove the two screws that secure the power seat switch to the inside of the seat cushion side shield (Fig. 3).
(8) Remove the power seat switch from the seat cushion side shield.
(9) Reverse the removal procedures to install. Tighten the mounting screws to 2.2 N·m (20 in. lbs.).
POWER LUMBAR SWITCH
(1) Disconnect and isolate the battery negative cable.
(2) Remove the three screws that secure the seat cushion side shield to the outboard seat cushion frame.
(3) Pull the seat side shield away from the seat cushion frame far enough to access the power seat switch and power lumbar switch wire harness connectors.
(4) Unplug the power seat switch and power lumbar switch wire harness connectors from the switches.
(5) Remove the seat side shield from the vehicle.
(6) Remove the two screws that secure the power lumbar switch to the inside of the seat side shield.
(7) Remove the power lumbar switch from the seat side shield.
(8) Reverse the removal procedures to install. Tighten the mounting screws to 2.2 N·m (20 in. lbs.).
POWER SEAT ADJUSTER AND MOTORS
(1) Move the seat to its fully forward position, if possible.
(2) Remove the single screw that secures each of the two rear seat track covers to the rear of the seat tracks and remove the covers.
(3) Remove the single screw that secures the rear of each of the two seat tracks to the floor panel.
(4) Move the seat to its fully rearward position, if possible.
(5) Disconnect and isolate the battery negative cable.
(6)
Remove the single screw that secures the front of each of the two seat tracks to the floor panel (Fig. 4).
(7) Tilt the seat rearward and unplug the power seat wire harness connector located on the floor below the seat cushion.
(8) Remove the seat and adjuster assembly from the vehicle.
(9) Remove the three screws that secure the outboard seat cushion side shield to the seat cushion frame and pull the shield away from the seat cushion. (10) For the driver side front seat only, if the vehicle is equipped with the optional memory seat module, the memory seat module must be removed from the inboard side of the driver side front seat. See Memory Seat Module in this group for the procedures.
(11) Remove the four nuts that secure the upper seat adjuster mounting rails to the seat cushion frame.
(12) Unplug the wire harness connectors from the power adjuster motors as required, depending upon how the vehicle is equipped, to separate the power seat adjuster and motors assembly from the seat cushion frame.
(13) Reverse the removal procedures to install. Tighten the seat mounting hardware as follows:
• Seat cushion frame to adjuster nuts - 20 N·m (15 ft. lbs.)
• Seat adjuster to floor pan screws - 29 N·m (20 ft. lbs.)
• Seat cushion side shield screws - 2.2 N·m (20 in. lbs.).
POWER RECLINER ADJUSTER AND MOTOR
(1) Move the seat to its fully forward and fully raised positions, if possible.
(2) Remove the three screws that secure the outboard seat cushion side shield to the seat cushion frame and pull the shield away from the seat cushion far enough to access the power recliner adjuster lower bracket.
(3) If possible, adjust the seat back with the power recliner switch far enough to access both of the two screws in the power recliner adjuster lower bracket.
(4) Disconnect and isolate the battery negative cable.
(5) Remove the two screws that secure the power recliner adjuster lower bracket to the seat cushion frame (Fig. 5).
(6) Remove the inboard seat back pivot screw. (7) Unplug any wire harness connectors between the seat back and the seat cushion, the number of which will vary with the vehicle equipment.
(8) Remove the seat back from the seat cushion and place it on a suitable work surface.
(9) Carefully pull up the side of the seat back cover far enough to access the two screws that secure the power recliner adjuster upper bracket to the seat back frame (Fig. 6). Refer to Group 23 - Body for the seat back cover removal procedures.
(10) Remove the power recliner adjuster and motor unit from the seat back frame.
(11) Reverse the removal procedures to install. Tighten the hardware as follows:
• Inboard pivot screw - 40 N·m (29 ft. lbs.) • Recliner adjuster bracket screws - 28 N·m (20 ft. lbs.)
• Seat cushion side shield screws - 2.2 N·m (20 in. lbs.).
POWER LUMBAR ADJUSTER AND MOTOR
(1) Remove the power recliner adjuster and motor from the seat back frame. See Power Recliner Adjuster and Motor in this group for the procedures.
(2) Remove all of the seat back trim from the seat back. Refer to Group 23 - Body for the procedures.
(3) Replace the seat back frame assembly, which includes the lumbar adjuster and motor (Fig. 7). (4) Reverse the removal procedures to install.
MEMORY SEAT MODULE
(1) Move the driver side front seat to its fully forward and fully raised positions, if possible.
(2) Remove the single screw that secures each of the two rear seat track covers to the rear of the seat tracks and remove the covers.
(3) Remove the single screw that secures the rear of each of the two seat tracks to the floor panel.
(4) Move the driver side seat to its fully rearward position, if possible.
(5) Disconnect and isolate the battery negative cable.
(6) Remove the single screw that secures the front of each of the two seat tracks to the floor panel.
(7) Carefully tilt the top of the seat back towards the outboard side of the vehicle.
(8) Release the two retainers that secure the memory seat module wire harness to the inboard seat adjuster top rail (Fig. 8).
(9) There are two snap clips that are molded into the side of the memory seat module closest to the seat adjuster, which help to secure the module to the riser portion of the stepped mounting bracket. Using a trim stick or another suitable wide flat-bladed tool, reach between the module and the seat adjuster to gently pry each of the two snap clips while pulling the module away from the mounting bracket.
(10) Slide the memory seat module off of the two mounting bracket slide tabs far enough to access and unplug the wire harness connectors.
(11) Remove the memory seat module from under the seat cushion.
(12) Reverse the removal procedures to install. Tighten the seat mounting hardware as follows:
• Seat cushion frame to adjuster nuts - 20 N·m (15 ft. lbs.)
• Seat adjuster to floor panel screws - 29 N·m (20 ft. lbs.).
NOTE: Following installation, it will be necessary to initialize the memory seat module. This is done by moving each of the power seat adjuster motors (including the power recliner and power lumbar motors) through its full range of motion using the power seat switches. In order to function properly, the memory seat module must “learn” the motor sensor values in each of the adjuster hard stop positions.