Power Seat Inoperative (w/A45)
Power Seat Inoperative (w/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 switch, and memory seat module (MSM) from the TELE SW/MSM fuse located in the body control module (BCM) fuse block. When a seat adjustment switch is operated, battery voltage is applied through the switch contacts to the appropriate switch signal circuit to the memory seat module (MSM) input to ground. The MSM responds to the input from the adjuster switch by commanding the selected seat motor to move in response to the switch signal. When a memory recall switch is pressed battery positive voltage is applied through the switch contacts and the switch signal circuit to the memory seat module (MSM). The MSM then commands the appropriate seat motors to move to the pre-recorded seat position stored in memory in response to the switch signal.
All 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 (MSM) is also referred to as the driver position module (DPM) 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
Power Seats System Description and Operation (Power Seats System 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)
Circuit/System Verification
Ignition ON, observe the scan tool seat switch parameters located in the driver position module data display menu while activating each switch. The reading should change between ACTIVE and INACTIVE as each switch is activated.
If the readings do not change between ACTIVE and INACTIVE as each switch is activated, refer to Seat Adjuster Switch Malfunction.
If the readings change between ACTIVE and INACTIVE as each switch is activated, refer to Seat Adjuster Motor Malfunction.
Circuit/System Testing
Seat Adjuster Switch Malfunction
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. Ignition ON, verify the scan tool seat switch parameters display INACTIVE for all switches.
• If the scan tool displays ACTIVE, test the appropriate switch signal circuit for a short to voltage. If the circuit tests normal, replace the MSM.
4. Install a 3 A fused jumper wire between the B+ circuit terminal E and the inoperative switch signal circuit. Verify the appropriate scan tool seat switch parameter is ACTIVE.
• If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
5. If all circuits test normal, test or replace the driver seat adjuster switch.
Seat Adjuster Motor Malfunction
1. Ignition OFF, disconnect the X2 harness connector at the MSM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal B11 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 X2 harness connector at the MSM.
4. Ignition OFF, disconnect the X1 harness connector at the seat adjuster motor assembly.
5. Connect a test lamp between the inoperative motor control circuit terminals of the inoperative motor.
6. Verify the test lamp illuminates as the appropriate seat adjuster switch is operated in both positions for the inoperative motor.
• If the test lamp does not illuminate as the switch is operated to both positions, test the appropriate motor control circuits for a short to ground or an open/high resistance. If the circuits test normal, replace the MSM.
7. If all circuits test normal, test or replace the seat adjuster motor assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Front Seat Adjuster Motor Replacement (Front Seat Adjuster Motor Replacement)
* Power Seat Switch Replacement (Power Seat Switch Replacement)
* Control Module References (Programming and Relearning)for MSM replacement, setup, and programming