Power Seat Malfunction (8-Way Without Memory A45)
Power Seat Malfunction (8-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 30 A fuse located in the underhood 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, 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 [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Sunshade - Left Front
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 appropriate seat switch in both directions.
* M51 Seat Horizontal Motor
* M50 Seat Front Vertical Motor
* M55 Seat Rear Vertical Motor
* M56 Seat 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
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 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 B 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 and the circuit fuse is good
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 fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for greater than 10 ohms between each B+ circuit listed below and ground.
* Control circuit terminal A - M50 Seat Front Vertical Motor
* Control circuit terminal K - M50 Seat Front Vertical Motor
* Control circuit terminal F - M55 Seat Rear Vertical Motor
* Control circuit terminal J - M55 Seat Rear Vertical Motor
* Control circuit terminal D - M51 Seat Horizontal Motor
* Control circuit terminal C - M51 Seat Horizontal Motor
* Control circuit terminal H - M56 Seat Recline Motor
* Control circuit terminal G - M56 Seat Recline Motor
• If 10 ohms or less, disconnect the motor and retest to verify if the short is in the circuit or the motor.
• If greater than 10 ohms, replace the S64 Seat Adjuster switch.
• 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 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, ignition ON.
3. Verify the test lamp turns ON when commanding the seat motor Up and Down or Forward and Rearward using the S64 Seat Adjuster Switch.
• If the test lamp remains OFF 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 turns ON 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 E 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 omhs between the B+ terminal E and each control terminal with the appropriate switch in the closed position.
• 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 B and each control terminal with the switch in the open position.
• 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 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.
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 Switch Replacement Driver Seat Adjuster Switch Replacement
* Front Seat Tilt Adjuster Actuator Replacement Front Seat Tilt Adjuster Actuator Replacement
* Driver or Passenger Seat Vertical Adjuster Actuator Replacement Driver or Passenger Seat Vertical Adjuster Actuator Replacement
* Front Seat Adjuster Actuator Replacement Front Seat Adjuster Actuator Replacement
* Driver or Passenger Seat Recliner Actuator Replacement Driver or Passenger Seat Recliner Actuator Replacement