Power Seat Inoperative (Coupe with Memory A45)
Power Seat Inoperative (Coupe 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) through a 10 A MSM fuse located in the rear fuse block. This voltage is used by the MSM for logic power and to supply reference voltage to the seat and lumbar adjuster switches. Battery positive voltage is also supplied at all times to the MSM through the a 25 A circuit breaker located in the rear fuse block. This voltage is connected to a power rail internal to the MSM and is used to drive the driver power seat motors, lumbar motor, the passenger seat horizontal motor, and the seat heater elements on vehicles equipped with heated seats. Each seat and lumbar 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 V. The MSM checks to see if the reference voltage is shorted to ground or battery before enabling any of the seat or lumbar motors.
All motors are reversible. For example, when the seat switch is operated to move the entire seat forward, battery positive 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 driver seat horizontal motor forward control circuit and ground through the driver seat horizontal motor rearward control circuit to the motor. 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.
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
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 Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool Seat 1 Inputs seat switch parameters while pressing the appropriate driver seat switch. The reading should change between Active and Inactive.
• If the reading does not change between the specified values, refer to the Driver Seat Adjuster Switch Circuit Test.
2. Command the appropriate driver seat motor in the Up/Down or Forward/Rearward directions with a scan tool. The seat should move up and down or forward and rearward as commanded.
• If the seat does not move up and down or forward and rearward, refer to the Driver Seat Motor Circuit Test.
3. Operate the passenger seat adjuster switches for the seat directional motors listed below in both directions. The seat should move in the commanded directions.
* Horizontal Motor
* Front Vertical Motor
* Rear Vertical Motor
* Recline Motor
• If the passenger power seat is inoperative in all directions, refer to Power Seat Inoperative (Without Memory A45) Power Seat Inoperative (Without Memory A45)Power Seat Inoperative (Coupe with Memory A45) Power Seat Inoperative (Sedan, Wagon with Memory A45) Power Seat Inoperative (Sedan, Wagon with Memory A45). Without Memory A45
4. Ignition ON, observe the scan tool Seat 2 Inputs Horizontal/Easy Entry Forward and Rearward Sw parameters while pressing the passenger seat horizontal switch in the forward and rearward directions. The readings should change between Active and Inactive.
• If the reading does not change between the specified values, refer to the Passenger Seat Adjuster Switch Circuit Test.
5. Command the passenger Seat Forward/Backward with a scan tool. The passenger seat should move horizontally forward and rearward as commanded.
• If the seat does not move forward and rearward, refer to the Passenger Seat Horizontal Motor Circuit Test.
Circuit/System Testing
Driver 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 3 A 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 upward switch terminal A (LHD)
* Front vertical upward switch terminal K (RHD)
* Front vertical downward switch terminal K (LHD)
* Front vertical downward switch terminal A (RHD)
* Rear vertical upward switch terminal F (LHD)
* Rear vertical upward switch terminal J (RHD)
* Rear vertical downward switch terminal J (LHD)
* Rear vertical downward switch terminal F (RHD)
* Horizontal forward switch terminal D
* Horizontal rearward switch terminal C
* Recline forward switch terminal H
* Recline rearward switch terminal G
• 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.
Driver Seat Motor Circuit Test
1. Ignition OFF, disconnect the X3 harness connector at the MSM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 5 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 X3 harness connector at the memory seat module and disconnect the X1 harness connector at the appropriate seat adjuster motor.
4. Connect a test lamp between control circuit terminal 1 and control circuit terminal 5.
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 an open/high resistance. If the circuits test normal replace the MSM.
6. If all circuits test normal, test or replace the seat adjuster motor.
Passenger Seat Adjuster Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the passenger seat adjuster switch.
2. Install a 3 A fused jumper wire between the B+ circuit terminal E and the appropriate signal circuit listed below. Verify the appropriate scan tool Horizontal/Easy Entry Forward or Rearward Sw parameter is Active.
* Horizontal forward switch terminal D
* Horizontal rearward switch terminal C
• If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the MSM.
3. If all circuits test normal, test or replace the seat adjuster switch.
Passenger Seat Horizontal Motor Circuit Test
1. Ignition OFF, disconnect the harness connector at the passenger seat horizontal motor.
2. Connect a test lamp between control circuit terminal 1 and control circuit terminal 5.
3. Ignition ON, command the passenger Seat Forward/Backward with a scan tool. The test lamp should turn ON when commanding the forward and backward 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 horizontal motor.
Component Testing
Seat Adjuster Switch
1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.
2. Test for infinite resistance between the B+ terminal E and each seat direction signal 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 the B+ terminal E and each seat direction signal terminal with the appropriate switch in the closed position.
• If greater than the specified range, replace the adjuster switch switch.
Seat Motor
1. Ignition OFF, disconnect the harness connector at the appropriate seat motor.
Note: When performing the following tests, make sure that the seat is not already in the position the test is attempting to produce.
2. Install a 30 A fused jumper wire between the control terminal 1 and 12 V. Momentarily install a jumper wire between the control terminal 5 and ground. The seat motor should momentarily perform the appropriate FORWARD/REARWARD/UP/DOWN function.
• If the function does not perform as specified, replace the seat motor.
3. Reverse the polarity of jumper wires; the a seat motor should perform in the opposite direction.
• If the function does not perform as specified, replace the seat motor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Front Seat Adjuster Switch Replacement - Driver Side (AQ9) Front Seat Adjuster Switch Replacement - Driver Side (AQ9)Front Seat Adjuster Switch Replacement - Driver Side (W2E) Front Seat Adjuster Switch Replacement - Driver Side (W2E)
* Front Seat Tilt Adjuster Actuator Replacement Front Seat Tilt Adjuster Actuator Replacement
* Front Seat Adjuster Actuator Replacement Front Seat Adjuster Actuator Replacement
* Driver Seat Outer Adjuster Rear Vertical Actuator Replacement Driver Seat Outer Adjuster Rear Vertical Actuator Replacement
* Front Seat Recliner Actuator Motor Replacement Front Seat Recliner Actuator Motor Replacement
* Control Module References Control Module References for MSM replacement, setup, and programming