Power Seat Malfunction
Power Seat Malfunction
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 switch. Battery voltage is supplied at all times to the seat switch through a 25 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, B+ 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 (Connector End Views By Name)
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
Operate the appropriate driver or passenger switches for the seat directional motors listed below in both directions. The seat should move in the commanded direction.
* M51 Horizontal Motor
* M50 Front Vertical Motor
* M55 Rear Vertical Motor
* M56 Recline Motor
If the power seat is inoperative in all directions, refer to the S64 Seat Switch Circuit Test.
If 1 or more of the seat adjuster motors operate, refer to the Seat Adjuster Motor Circuit Test.
Circuit/System Testing
S64 Seat Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the appropriate S64 seat adjuster switch.
2. Test for less than 5 Ohms between the appropriate ground circuit terminal listed below and ground:
* 8-way power seat terminal B
* 2-way power seat terminal A and terminal C
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the appropriate B+ circuit listed below and ground:
* 8-way power seat terminal E
* 2-way power seat terminal D
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. If all circuits test normal, test or replace the S64 seat adjuster switch.
Seat Adjuster Motor Circuit Test
1. Ignition OFF, disconnect the harness connector at the appropriate seat motor listed below:
* M50 seat front vertical motor
* M55 seat rear vertical motor
* M51 seat horizontal motor
* M56 seat recline motor
2. Connect a test lamp between control circuit terminal 1 and control circuit terminal 5.
3. Ignition ON, command the seat motor Up and Down or Forward and Rearward using the seat switch. The test lamp should turn ON when commanding the up and down or forward and rearward states.
• If the test lamp remains OFF for either of the commands, test the control circuits for a short to ground or an open/high resistance. If the circuits test normal, test or replace the S64 seat adjuster switch.
4. If all circuits test normal, test or replace the seat motor.
Component Testing
Seat Switch Test
1. Ignition OFF, disconnect the harness connector at the S64 seat adjuster switch.
2. Test for infinite resistance between the ground terminal and each control terminal with the switch in the open position.
• If less than the specified value, replace the S64 seat adjuster switch.
3. Test for less than 1 Ohms between the ground terminal and each control terminal with the appropriate switch in the closed position.
• If greater than the specified range, replace the S64 seat adjuster switch.
4. Test for less than 1 Ohms between the B+ terminal and each control terminal with the switch in the open position.
• If greater than the specified range, replace the S64 seat adjuster switch.
Seat Motor
1. Ignition OFF, disconnect the harness connector at the appropriate seat motor listed below:
* M50 seat front vertical motor
* M55 seat rear vertical motor
* M51 seat horizontal motor
* M56 seat 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. 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 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.
* Driver or Passenger Seat Adjuster Switch Replacement (Driver/Passenger Seat 4-Way Hybrid) (Driver or Passenger Seat Adjuster Switch Replacement (Driver/Passenger Seat 4-Way Hybrid))
* Front Seat Tilt Adjuster Actuator Replacement (Driver/Passenger Seat 6-Way Hybrid) (Front Seat Tilt Adjuster Actuator Replacement (Driver/Passenger Seat 6-Way Hybrid))Front Seat Tilt Adjuster Actuator Replacement (Driver/Passenger Seat 8-Way Power) (Front Seat Tilt Adjuster Actuator Replacement (Driver/Passenger Seat 8-Way Power))
* Driver or Passenger Seat Adjuster Vertical Actuator Replacement (4/6/8-Way) (Service and Repair)
* Front Seat Adjuster Actuator Replacement (8-Way Power) (Front Seat Adjuster Actuator Replacement (8-Way Power))
* Front Seat Adjuster Motor Replacement (Driver or Passenger Seat 8-Way Power) (Front Seat Adjuster Motor Replacement (Driver or Passenger Seat 8-Way Power))
* Front Seat Recliner Actuator Motor Replacement (Driver or Passenger Seat 8-Way Power) (Front Seat Recliner Actuator Motor Replacement (Driver or Passenger Seat 8-Way Power))