Power Seat Inoperative (w/Memory)
Power Seat Inoperative (w/Memory)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
Battery voltage is supplied to the memory seat module (MSM) through the power seat circuit breaker. The MSM supplies the seat adjuster switch assembly with a battery positive reference voltage. While the seat adjuster switches are in an inactive state the switch contacts are closed to the adjuster switch ground circuit. When a seat adjuster switch is pressed to an active state the switch contact is closed to the reference voltage circuit. Battery voltage on a switch signal circuit indicates to the MSM the switch status is active. Each seat adjuster motor is controlled by the MSM through 2 motor control circuits. While the seat adjuster motors are in an inactive state the motor control circuits are closed to ground circuit contacts within the MSM. The MSM operates the seat adjuster motors by switching one of a motor's control circuits to battery voltage. The seat adjuster motors are bidirectional and the direction of adjuster motor rotation is determined by which of the adjuster motor control circuits is switched to battery voltage while the other remains grounded.
Circuit/System Verification
1. Ignition ON, observe the scan tool seat adjuster switch parameters while operating each adjuster switch in both directions. The reading should change between Inactive and the desired direction.
^ If any of the switch input parameters are Inactive or Invalid while the switch is pressed, refer to the affected Switch Circuit Test
2. If the switch inputs to the MSM function normal, refer to Motor Control Circuit Test.
Circuit/System Testing
Seat Adjuster Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal E and ground.
^ If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
3. Verify the scan tool switch parameter is Inactive.
^ If not the specified value, test the affected signal circuit terminal listed for a short to voltage. If the circuit tests normal, replace the memory seat module.
* Recline forward terminal F
* Recline rearward terminal A
* Horizontal forward terminal D
* Horizontal rearward terminal C
* Rear down terminal G
* Rear up terminal J
* Front up terminal K
* Front down terminal H
4. Install a 3A fused jumper wire between the affected signal circuit terminal listed and the B+ circuit terminal E. Verify the scan tool switch parameter is the desired direction.
* Recline forward terminal F
* Recline rearward terminal A
* Horizontal forward terminal D
* Horizontal rearward terminal C
* Rear down terminal G
* Rear up terminal J
* Front up terminal K
* Front down terminal H
^ If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the memory seat module.
5. If all circuits test normal, test or replace the seat adjuster switch.
Lumbar Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the lumbar switch.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal E and ground.
^ If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
3. Verify the scan tool switch parameter is Inactive.
^ If not the specified value, test the affected signal circuit terminal listed for a short to voltage. If the circuit tests normal, replace the memory seat module.
* Lumbar forward terminal A
* Lumbar rearward terminal D
4. Install a 3A fused jumper wire between the affected signal circuit terminal listed and the B+ circuit terminal E. Verify the scan tool switch parameter is the desired direction.
* Lumbar forward terminal A
* Lumbar rearward terminal D
^ If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the memory seat module.
5. If all circuits test normal, test or replace the lumbar switch.
Motor Control Circuit Test
1. Ignition OFF, disconnect the X1 harness connector at the MSM.
2. Verify that a test lamp illuminates between the B+ circuit terminal C and ground.
^ If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
3. Connect the X1 harness connector at the MSM.
4. Ignition OFF, disconnect the harness connector at the affected seat motor.
5. Ignition OFF, test for less than 1.0 ohm of resistance between the control circuit terminal A and ground.
^ If greater than the specified range, test the control circuit for an open/high resistance. If circuits test normal, replace the MSM.
6. Ignition OFF, test for less than 1.0 ohm of resistance between the control circuit terminal B and ground.
^ If greater than the specified range, test the control circuit for an open/high resistance. If circuits test normal, replace the MSM.
7. Connect a test lamp between control circuit terminal A and control circuit terminal B.
8. Command the affected seat motor in both directions with a scan tool. The test lamp should turn ON when commanding the motor in both directions.
^ If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, replace the MSM.
9. If all circuits test normal, test or replace the affected motor assembly.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Power Seat Switch Replacement
* Front Seat Lumbar Control Switch Replacement
* Power Seat Adjuster Mechanism Replacement
* Front Seat Lumbar Support Replacement