Power Seat Malfunction (Without Memory)
Power Seat Malfunction (Without Memory)
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- 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 rear l fuse block. When the seat switches are in an inactive state, the switch contacts are closed to the switch B+ circuit.
All seat motors are reversible. For example, when the seat horizontal forward switch is pressed to move the entire seat forward, ground 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 B+ 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
- Passenger Seat Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Power Seats System Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Circuit/System Verification
Operate the appropriate driver or passenger S64 seat adjuster 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
Circuit/System Testing
S64 Seat Adjuster 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 ground circuit terminal E and ground.
3. If greater than the specified range, test the ground circuit for an open/high resistance.
4. Ignition ON, verify that a test lamp illuminates between the appropriate B+ circuit terminal B and ground.
5. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
6. 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 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.
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.
4. 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 switch.
5. 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 switch.
2. Test for infinite resistance between the ground terminal and each control terminal with the switch in the open position.
3. If less than the specified value, replace the S64 seat switch.
4. Test for less than 1 Ohms between the ground terminal and each control terminal with the appropriate switch in the closed position.
5. If greater than the specified range, replace the S64 seat switch.
6. Test for less than 1 Ohms between the B+ terminal and each control terminal with the switch in the open position.
7. If greater than the specified range, replace the S64 seat switch.
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
2. NOTE: When performing the following tests, make sure that the seat is not already in the position the test is attempting to produce.
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.
3. If the function does not perform as specified, replace the seat motor.
4. Reverse the polarity of jumper wires. The seat motor should perform in the opposite direction.
5. If the function does not perform as specified, replace the seat motor.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Driver Seat Adjuster Switch Replacement
- Passenger Seat Adjuster Switch Replacement
- Driver or Passenger Seat Cushion Frame Replacement