Power Seat Malfunction (Without Memory A45)
Power Seat Malfunction (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
The driver seat without memory and the passenger seat are completely controlled through their respective seat adjuster switches. Battery voltage is supplied at all times to the seat adjuster switch through a circuit breaker located in the instrument panel fuse block. When the seat switches are in an inactive state, the switch contacts are closed to the switch ground circuit.
All seat motors are reversible. For example, when the seat horizontal forward switch is pressed to move the entire seat forward, battery voltage is applied through the switch contacts and the seat horizontal motor forward control circuit to the motor. With the horizontal motor rearward switch contacts closed to the switch ground circuit, the motor runs in order 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 voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction. All seat motors are powered this way.
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 seat directional motors listed below operate while operating the seat switches in both directions.
* M51P Horizontal Motor
* M50P Front Vertical Motor
* M55P Rear Vertical Motor
* M56P Recline Motor
• If all seat motors do not operate
Refer to Circuit/System Testing - Seat Adjuster Switch Circuit Test.
• If 1 or more seat motors operate but not all
Refer to Circuit/System Testing - Seat Motor Circuit Test.
• If all seat motors operate
2. All OK.
Circuit/System Testing
Seat Adjuster Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the S64 seat adjuster switch.
2. Test for less than 5 ohms between the ground circuit terminal 2 and ground.
• If 5 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 5 ohms
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal 6 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. Test or replace the S64 seat adjuster switch.
Seat Motor Circuit Test
1. Ignition OFF, disconnect the harness connector at the appropriate seat motor listed below:
* M50 front vertical motor
* M55 rear vertical motor
* M51 horizontal motor
* M56 recline motor
2. Connect a test lamp between control circuit terminal 1 and control circuit terminal 5, ignition ON.
3. Verify the test lamp illuminates when commanding the seat motor Up and Down or Forward and Rearward 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
4. Test or replace the seat 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 and each control terminal with the switch in the open position.
• If less than infinite resistance
Replace the S64 seat adjuster switch.
• If infinite resistance
3. Test for less than 2 ohms between the B+ terminal and each control terminal with the appropriate switch in the closed position.
• If 2 ohms or greater
Replace the S64 seat adjuster switch.
• If less than 2 ohms
4. Test for less than 2 ohms between the ground terminal and each control terminal with the switch in the open position.
• If 2 ohms or greater
Replace the S64 seat adjuster switch.
• If less than 2 ohms
5. All OK.
Seat Motor
1. Ignition OFF, disconnect the harness connector at the appropriate seat motor listed below:
* M50 front vertical motor
* M55 rear vertical motor
* M51 horizontal motor
* M56 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 or Passenger Seat Adjuster and Recliner Switch Replacement Driver or Passenger Seat Adjuster and Recliner Switch Replacement