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 at all times to the memory seat module (MSM) from the MSM 10A fuse. This voltage is used by the MSM for logic power and to supply battery reference voltage to the seat adjuster switches. Battery positive voltage is also supplied at all times to the MSM from the LT/PWR/SEAT 25A circuit breaker. This voltage is connected to a power rail internal to the MSM and is used to drive the power seat motors, lumbar motors, and seat heater elements on vehicles equipped with heated seats. Each seat and lumbar adjuster motor is controlled by the MSM through 2 motor control circuits. The MSM connects all motor control circuits on the power rail to a common reference point whenever they are not in operation. This reference point is biased to approximately 2.5 volts. The MSM checks to see if the reference voltage is shorted to ground or battery before enabling any of the seat or lumbar motors.

Diagnostic Fault Information






Circuit/System Verification

1. Ignition ON, observe the scan tool memory seat module seat switch parameters. Verify that the seat switch parameters are INACTIVE while the switch is in an inactive state.

^ If not the specified value, refer to Seat Adjuster Switch Malfunction.

2. Observe the scan tool memory seat module seat switch parameters while pressing the appropriate seat switch. The reading should display ACTIVE.

^ If not the specified value, refer to Seat Adjuster Switch Malfunction.

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. If the circuit tests normal, replace the MSM.

3. Install a 3A fused jumper wire between the inoperative switch signal circuit terminal and the B+ circuit terminal E. With a scan tool, verify the appropriate seat adjuster switch parameter is ACTIVE.

^ 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.

Component Testing

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

^ If less than the specified value, replace the seat adjuster switch.

3. Test for less than 1 ohm of resistance between each signal terminal and the B+ terminal E with the switch in the closed position.

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

Repair Instructions

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

* Power Seat Switch Replacement