Power Seat Inoperative (With Memory A45)
Power Seat Inoperative (With Memory A45)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
Battery positive voltage is supplied at all times to the seat adjuster switch, memory seat adjuster switch, and memory seat module (MSM) from the TILT/TELE SW/MEM SEAT MOD 10A fuse located in the Body Control Module (BCM) fuse block. When a seat adjustment switch is pressed, battery voltage is applied through the switch contacts and the appropriate switch signal circuit to the MSM. In response to this signal, the MSM commands the selected seat motor to move in response to the switch signal.
All power seat motors are reversible. For example, when the seat switch is operated to moved the entire seat forward, battery positive voltage is applied through the horizontal forward switch contacts and the power seat horizontal forward switch signal circuit to the MSM. In response to this signal, the MSM applies battery positive voltage through the driver seat horizontal motor forward control circuit to the horizontal motor. The MSM supplies ground to the motor through the driver seat horizontal motor rearward control circuit. The motor runs to drive the entire seat forward until the switch is released. Moving the entire seat rearward works similarly to moving the entire seat forward, except that battery positive voltage and ground are applied on the opposite circuits causing the motor to run in the opposite direction. All other seat motors are also powered this way.
Diagnostic Aids
The memory seat module is also referred to as the Driver Position Module in certain scan tool menus.
Reference Information
Schematic Reference
Driver Seat Schematics (Driver Seat Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Memory Seats Description and Operation (Memory Seats Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
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 driver 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 all scan tool Driver Position Module power seat switch parameters are Inactive.
• If not the specified value, test the appropriate signal circuit listed below for a short to voltage. If the circuit tests normal, replace the MSM.
* Front vertical down switch terminal J
* Front vertical up switch terminal K
* Horizontal forward switch terminal D
* Horizontal rearward switch terminal C
* Rear vertical down switch terminal G
* Rear vertical up switch terminal H
* Recline forward switch terminal F
* Recline rearward switch terminal A
4. Install a 3A fused jumper wire between the B+ circuit terminal E and the appropriate signal circuit listed below. Verify the appropriate scan tool seat switch parameter is Active.
* Front vertical down switch terminal J
* Front vertical up switch terminal K
* Horizontal forward switch terminal D
* Horizontal rearward switch terminal C
* Rear vertical down switch terminal G
* Rear vertical up switch terminal H
* 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.
5. 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 seat adjuster motor assembly.
2. Connect a test lamp between the appropriate control circuits listed below:
* Seat horizontal motor terminal A and terminal B
* Seat front vertical motor terminal C and terminal D
* Seat rear vertical motor terminal E and terminal F
3. 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 an open/high resistance. If the circuits test normal, replace the MSM.
4. 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 seat 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 an open/high resistance. If the circuits test normal, replace the MSM.
4. If all circuits test normal, test or replace the seat recline motor.
Component Testing
Seat Adjuster Switch Test
1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.
2. Test for infinite resistance between the B+ terminal E and the switch terminals listed below and with the switch in the open position.
* 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, replace the seat adjuster switch.
3. Test for less than 1 ohm between the B+ terminal E and each the switch terminals listed below with the appropriate switch in the closed position.
* 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 greater than the specified range, replace the seat adjuster switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Driver Seat Adjuster and Recliner Switch Replacement (Driver Seat Adjuster and Recliner Switch Replacement)
* Driver Seat Adjuster Replacement (Driver Seat Adjuster Replacement)
* Control Module References (Programming and Relearning) for MSM replacement, setup, and programming