Power Seat Malfunction (2-Way Without Memory A45)
Power Seat Malfunction (2-Way Without 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 adjuster switch through a 25 A circuit breaker located in the instrument panel fuse block. When the seat switch is in a inactive state, the switch contacts are closed to the switch ground circuit.
The seat vertical motor is reversible. For example, when the seat adjuster switch is pressed to move the entire seat up, battery voltage is applied through the switch contacts and the seat vertical motor up control circuit to the motor. With the vertical motor down switch contacts closed to the switch ground circuit, the motor runs in order to drive the entire seat up until the switch is released. Moving the entire seat down works similarly to moving the entire seat up, except that battery voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction.
Reference Information
Schematic Reference
* Driver Seat Schematics Driver Seat Schematics
* Passenger Seat Schematics Passenger Seat Schematics
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Power Seats System Description and Operation Power Seats System
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
Circuit/System Verification
1. Verify the driver or passenger M55 Seat Rear Vertical Motor operates when pressing the seat adjuster switch in both directions.
• If the M55 Seat Rear Vertical Motor does not operate
Refer to Circuit/System Testing.
• If the M55 Seat Rear Vertical Motor operates
2. All OK.
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S64 Seat Adjuster Switch. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 omhs between the ground circuit terminal H and ground:
• If 10 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 10 omhs
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal E and ground.
• If the test lamp does not illuminate
1. Ignition OFF
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the circuit breaker is not open and there is voltage at the circuit breaker.
• If the test lamp illuminates
5. Ignition OFF, connect the harness connector at the S64 Seat Adjuster Switch and disconnect the harness connector at the M55 Seat Rear Vertical Motor.
6. Connect a test lamp between control circuit terminal 1 and control circuit terminal 5, ignition ON.
7. Verify the test lamp illuminates when commanding the M55 Seat Rear Vertical Motor Up and Down using the seat adjuster switch.
• If the test lamp does not illuminate during either of the commands
1. Ignition OFF, disconnect the harness connector at the S64 Seat Adjuster Switch.
2. 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, test or replace the S64 Seat Adjuster Switch.
• If the test lamp illuminates during each of the commands
8. Test or replace the M55 Seat Rear Vertical Motor.
Component Testing
Seat Adjuster Switch Test
1. Ignition OFF, disconnect the harness connector at the S64 Seat Adjuster Switch.
2. Test for infinite resistance between the B+ terminal E and each control terminal listed below with the switch in the open position.
* Terminal A
* Terminal D
• If less than infinite resistance
Replace the S64 Seat Adjuster Switch.
• If infinite resistance
3. Test for less than 2 omhs between the B+ terminal E and each control terminal listed below with the appropriate switch in the closed position.
* Terminal A
* Terminal D
• If 2 omhs or greater
Replace the S64 Seat Adjuster Switch.
• If less than 2 omhs
4. Test for less than 2 omhs between the ground terminal H and each control terminal with the switch in the open position.
* Terminal A
* Terminal D
• If 2 omhs or greater
Replace the S64 Seat Adjuster Switch.
• If less than 2 omhs
5. All OK.
Seat Motor
1. Ignition OFF, disconnect the harness connector at the M55 Seat Rear Vertical 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 UP/ DOWN function.
• If the motor does not perform the UP/ DOWN function
Replace the motor.
• If the motor performs the UP/ DOWN function
4. Reverse the jumper wires; the motor should perform UP/ DOWN function.
• If the motor does not perform the UP/ DOWN function
Replace the motor.
• If the motor performs the UP/ DOWN function
5. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Driver Seat Adjuster Switch Replacement Driver Seat Adjuster Switch Replacement
* Passenger Seat Adjuster Switch Replacement Passenger Seat Adjuster Switch Replacement
* Front Seat Tilt Adjuster Actuator Replacement Front Seat Tilt Adjuster Actuator Replacement