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Power Seat Inoperative (With Memory A45)




Power Seat Inoperative (With Memory A45)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information





Circuit/System Description

Battery voltage is supplied at all times to the memory seat module (MSM) from the 10A DPM fuse located in the left rear fuse block. This voltage is used by the MSM for logic power and to supply battery reference voltage to the seat and lumbar adjuster switches. Battery voltage is supplied at all times to the MSM from the SEATS 30A circuit breaker located in the left rear fuse block. This voltage is used by the MSM to drive the driver seat adjuster motors, recline motor and the lumbar motors.

All motors are reversible. For example, when the seat switch is pressed to move the seat forward, battery voltage is applied through the switch contacts and the seat horizontal forward switch signal circuit to the MSM. In response to this signal, the MSM applies battery voltage through the seat horizontal motor forward control circuit and ground through the seat horizontal motor rearward control circuit to the motor. The motor runs to drive the seat forward until the switch is released. Moving the seat rearward works similarly to moving the seat forward, except that battery positive voltage and ground are applied on the opposite circuits causing the motor to run in the opposite direction.

Diagnostic Aids

The scan tool may reference the Memory Seat Module (MSM) as the Driver Position Module.

Reference Information
Schematic Reference

Driver Seat Schematics (Driver Seat Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* Power Seats System Description and Operation (with A45 Disabled) (Power Seats System (with A45 Disabled))Power Seats System Description and Operation (Without Memory A45) (Power Seats System (Without Memory A45))
* Memory Seats Description and Operation (Memory Seats)

Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Ignition ON, observe the scan tool Driver Position Module seat switch parameters while pressing the appropriate seat switch. The reading should change between Inactive and Active.

• If the reading does not change between the specified values, refer to the Seat Adjuster Switch Circuit Test.

2. If all seat switch inputs to the MSM function normal, refer to the appropriate test listed below:

* Seat Motor Control Circuit Test
* Recline 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 appropriate B+ circuit terminal listed below and ground.

* B+ terminal E (LHD)
* B+ terminal A (RHD)

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.

3. Install a 3 A fused jumper wire between the B+ circuit terminal E (LHD) or terminal A (RHD) and the appropriate signal circuit terminal listed below. Verify the appropriate scan tool seat switch parameter is Active.

* Front vertical upward switch terminal K
* Front vertical downward switch terminal J
* Rear vertical upward switch terminal H
* Rear vertical downward switch terminal G
* Horizontal forward switch terminal D
* Horizontal rearward switch terminal C
* Recline forward switch terminal F
* Recline rearward switch terminal A

• If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the MSM.

4. If all circuits test normal, test or replace the seat adjuster switch.

Seat Motor Control Circuit Test
1. Ignition OFF, disconnect the X1 harness connector at the MSM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal B and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect the X1 harness connector at the MSM and disconnect the X1 harness connector at the seat adjuster motor assembly.
4. Connect a test lamp between the appropriate control circuits listed below:

* Seat horizontal motor terminal 3 and terminal 6
* Seat front vertical motor terminal 2 and terminal 5
* Seat rear vertical motor terminal 1 and terminal 4

5. Ignition ON, command the appropriate seat motor in the Up/Down or Forward/Rearward directions with a scan tool. The test lamp should turn ON when commanding the up and down or forward and rearward states.

• If the test lamp remains OFF during either of the commands, test the control circuits for a short to ground or an open/high resistance. If the circuits test normal replace the MSM.

6. If all circuits test normal, test or replace the seat motor.

Recline Motor Control Circuit Test
1. Ignition OFF, disconnect the X1 harness connector at the recline motor.
2. Connect a test lamp between control circuit terminal A and control circuit terminal B.
3. Ignition ON, command the Recline Forward/Rearward with a scan tool. The test lamp should turn ON when commanding the forward and rearward states.

• If the test lamp remains OFF during either of the commands, test the control circuits for a short to ground or an open/high resistance. If the circuits test normal, replace the MSM.

4. If all circuits test normal, test or replace the recline motor.

Component Test

Seat Adjuster Switch
1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.
2. Test for infinite resistance between each seat direction signal terminal and the B+ terminal with the switch in the open position.

• If not the specified value, replace the seat adjuster switch.

3. Test for less than 1 Ohms between each seat direction signal terminal and the B+ terminal with the appropriate switch in the closed position.

• If greater than the specified range, replace the seat adjuster switch.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Power Seat Switch Replacement (Power Seat Switch Replacement)
* Front Seat Adjuster Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for MSM replacement, setup, and programming

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