Power Seat Malfunction (With Memory A45)
Power Seat Malfunction (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 seat memory control module through a fuse located in the underhood fuse block. This voltage is used by the module for logic power. Battery positive voltage is also supplied at all times to the seat memory control module through a circuit breaker located in the instrument panel fuse block. This voltage is connected to a power rail internal to the seat memory control module and is used to drive the power seat motors and the seat heater elements on vehicles equipped with heated seats. Each seat motor is controlled by the seat memory control module through 2 motor control circuits. The seat memory control module 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 seat memory control module checks to see if the reference voltage is shorted to ground or battery before enabling any of the seat motors.
All motors are reversible. For example, when the seat switch is operated to move the entire seat forward, the switch signal circuit from the seat memory control module is pulled low indicating the entire seat forward command. In response to this signal, the seat memory control module 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 Sunshade - Left (DH6)
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.
2. Verify the scan tool seat switch parameters listed below change between Inactive and Forward/Rearward or Up/Down when pressing the appropriate switch.
* Driver Seat Horizontal Switch
* Driver Seat Cushion Front Vertical Switch
* Driver Seat Cushion Rear Vertical Switch
* Driver Seat Back Switch
• If the parameter does not change
Refer to the Driver Seat Adjuster Switch Circuit Test
• If the parameter changes
3. Verify the seat directional motors listed below operate while operating the appropriate driver seat switches in both directions.
* M51D♦Horizontal Motor
* M50D♦Front Vertical Motor
* M55D♦Rear Vertical Motor
* M56D♦Recline Motor
• If any seat motor does not operate
Refer to the Seat Motor Control Circuit Test.
• If all seat motors operate
4. All OK.
Circuit/System Testing
Driver Seat Adjuster Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the S64D♦driver seat adjuster switch.
2. Verify that all scan tool driver seat switch parameters listed below are Inactive:
* Driver Seat Cushion Front Vertical Switch
* Driver Seat Cushion Rear Vertical Switch
* Driver Seat Horizontal Switch
* Driver Seat Back Switch
• If not Inactive
1. Ignition OFF, disconnect the harness connector at the K40♦seat memory control module.
2. Test for infinite resistance between the appropriate signal circuit terminal listed below and ground:
* Front vertical upward switch terminal♦A
* Front vertical downward switch terminal♦K
* Rear vertical upward switch terminal♦F
* Rear vertical downward switch terminal♦J
* Horizontal forward switch terminal♦D
* Horizontal rearward switch terminal♦C
* Recline forward switch terminal♦H
* Recline rearward switch terminal♦G
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K40♦seat memory control module.
• If Inactive
3. Install a 3♦A fused jumper wire between the appropriate signal circuit terminal listed below and the ground circuit terminal♦E.
* Front vertical upward switch terminal♦A
* Front vertical downward switch terminal♦K
* Rear vertical upward switch terminal♦F
* Rear vertical downward switch terminal♦J
* Horizontal forward switch terminal♦D
* Horizontal rearward switch terminal♦C
* Recline forward switch terminal♦H
* Recline rearward switch terminal♦G
4. Verify the scan tool seat switch parameter is Forward/Rearward or UP/Down.
• If not Forward/Rearward or UP/Down
1. Ignition OFF, disconnect the harness connector at the K40♦seat memory control module, ignition ON.
2. Test for less than 1♦V between the signal circuit terminal and ground.
• If 1♦V or greater, repair the short to voltage on the circuit.
• If less than 1♦V
3. Ignition OFF.
4. Test for less than 2♦ohms in the signal circuit end to end.
• If 2♦ohms or greater, repair the open/high resistance in the circuit.
• If less than 2♦ohms, replace the K40♦seat memory control module.
• If Forward/Rearward or UP/Down
5. Test or replace the S64D♦driver seat adjuster switch.
Seat Motor Control Circuit Test
1. Ignition OFF, disconnect the X4 harness connector at the K40♦seat memory control module.
2. Test for less than 5♦omhs between each ground circuit terminal listed below and ground:
* Terminal♦3
* Terminal♦6
• If 5♦omhs or greater
1. Ignition OFF.
2. Test for less than 2♦omhs in the ground circuit end to end.
• If 2♦omhs or greater, repair the open/high resistance in the circuit.
• If less than 2♦omhs, repair the open/high resistance in the ground connection.
• If less than 5♦omhs
3. Ignition ON.
4. Verify that a test lamp illuminates between the B+ circuit terminal♦5 and ground.
• If the test lamp does not illuminate.
1. Ignition OFF.
2. Test for less than 2♦omhs in the B+ circuit end to end.
• If 2♦omhs or greater, repair the open/high resistance in the circuit.
• If less than 2♦omhs, verify the circuit breaker is OK and there is voltage at the circuit breaker.
• If the test lamp illuminates.
5. Ignition OFF, connect the X4 harness connector at the K40♦seat memory control module and disconnect the harness connector at the appropriate seat motor listed below:
* M50D♦seat front vertical motor
* M55D♦seat rear vertical motor
* M51D♦seat horizontal motor
* M56D♦seat back recline motor
6. Connect a test lamp between control circuit terminal♦1 and control circuit terminal♦5, ignition ON.
Note: Once a seat motor is commanded On using the scan tool, the seat function may not work using the seat adjuster switch until you back out of the scan tool Control Functions menu.
7. Verify the test lamp illuminates when commanding the seat motor in the Up/Down or Forward/Rearward states with a scan tool.
• If the test lamp does not illuminate during either of the commands
1. Ignition OFF, disconnect the X4 harness connector at the K40♦seat memory control module.
2. Test for infinite resistance between each control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2♦ohms in each control circuit end to end.
• If 2♦ohms or greater, repair the open/high resistance in the circuit.
• If less than 2♦ohms, replace the K40♦seat memory control module.
• If the test lamp illuminates during each of the commands
8. Test or replace the seat motor.
Component Testing
Seat Adjuster Switch Test
1. Ignition OFF, disconnect the harness connector at the S64D♦driver seat adjuster switch.
2. Test for infinite resistance between the ground terminal♦E and each signal terminal with the switch in the open position.
• If less than infinite resistance
Replace the S64D♦driver seat adjuster switch.
• If infinite resistance
3. Test for less than 2♦omhs between the ground terminal♦E and each signal terminal with the appropriate switch in the closed position.
• If 2♦omhs or greater
Replace the S64D♦driver seat adjuster switch.
• If less than 2♦omhs
4. All OK.
Seat Motor
1. Ignition OFF, disconnect the harness connector at the appropriate seat motor listed below:
* M50D♦front vertical motor
* M55D♦rear vertical motor
* M51D♦horizontal motor
* M56D♦recline 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 control terminal♦1 and 12♦V.
3. Momentarily install a jumper wire between control terminal♦5 and ground. The seat motor should momentarily perform the appropriate FORWARD/ REARWARD/ UP/ DOWN function.
• If the motor does not perform the FORWARD/ REARWARD/ UP/ DOWN function
Replace the motor.
• If the motor performs the FORWARD/ REARWARD/ UP/ DOWN function
4. Reverse the jumper wires; the motor should perform FORWARD/ REARWARD/ UP/ DOWN function.
• If the motor does not perform the FORWARD/ REARWARD/ UP/ DOWN function
Replace the motor.
• If the motor performs the FORWARD/ REARWARD/ UP/ DOWN function
5. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Driver Seat Adjuster and Recliner Switch Replacement Driver Seat Adjuster and Recliner Switch Replacement
* 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
* Driver or Passenger Seat Recliner Actuator Replacement Driver or Passenger Seat Recliner Actuator Replacement
* Control Module References Control Module References for seat memory control module replacement, programming and setup