Lumbar Support Malfunction (Without Memory A45)
Lumbar Support 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 seat lumbar support without memory is controlled through the seat lumbar support switch and the lumbar support control module. Battery voltage is supplied at all times to the seat lumbar support switch through a circuit breaker that is located in the rear fuse block. When the lumbar support switches are in an inactive state, the switch contacts are closed to the switch ground circuit.
Both lumbar motors are reversible. For example, when the lumbar horizontal forward switch is pressed to move the lumbar support forward, battery voltage is applied through the switch contacts and the lumbar motor forward control circuit to the lumbar support control module. The lumbar support control module then directs this voltage to the appropriate lumbar motor move in response to the switch signals. The motor is grounded through the lumbar motor rearward switch contacts, through the lumbar support control module, and the lumbar motor rearward control circuit to the motor. The motor runs in order to drive the lumbar support forward toward the occupants back until the switch is released. Moving the lumbar support rearward works similarly to moving the lumbar support forward, except that battery positive 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
Lumbar Support Description and Operation (Without Memory A45) Lumbar Support (Without Memory A45)Lumbar Support Description and Operation (With Memory A45) Lumbar Support (With Memory A45)
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. Ignition ON.
2. Verify that all power seat functions operate when being controlled by the S64 Seat Adjuster Switches.
• If any power seat function does not operate
Refer to Power Seat Malfunction (Without Memory A45) Power Seat Malfunction (Without Memory A45)Power Seat Malfunction (With Memory A45) Power Seat Malfunction (With Memory A45).
• If all power seat functions operate
3. Refer to Circuit/System Testing.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the appropriate K104 Seat Lumbar Support Control Module.
2. Connect a test lamp between each signal circuit terminal listed below and ground one at a time, ignition ON.
* Upper lumbar forward signal terminal 1
* Upper lumbar rearward signal terminal 5
* Lower lumbar up signal terminal 2
* Lower lumbar down signal terminal 6
3. Verify the test lamp turns ON and OFF when pressing and releasing the appropriate lumbar switch.
• If the test lamp remains OFF
1. Ignition OFF, disconnect the X2 harness connector at the S64 Seat Adjuster Switch.
2. Test for infinite resistance between the signal circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal 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 64 Seat Adjuster Switch.
• If the test lamp remains ON
1. Ignition OFF, disconnect the X2 harness connector at the S64 Seat Adjuster Switch, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, test or replace the S64 Seat Adjuster Switch.
• If the test lamp turns ON and OFF
4. Ignition OFF, connect the harness connector at the K104 Seat Lumbar Support Control Module and disconnect the harness connector at the appropriate M53 Seat Lumbar Support Motor.
5. Connect a test lamp between control circuit terminal A and control circuit terminal B, ignition ON.
6. Verify the test lamp turns ON when commanding the lumbar support motor Up/Down or Forward/Rearward using the lumbar support switch.
• If the test lamp remains OFF
1. Ignition OFF, disconnect the harness connector at the K104 Seat Lumbar Support Control Module.
2. Test for infinite resistance between each control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the 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 K104 Seat Lumbar Support Control Module.
• If the test lamp turns ON
7. Test or replace the M53 Seat Lumbar Support Motor.
Component Testing
Lumbar Support Switch
1. Ignition OFF, disconnect the X2 harness connector at the appropriate S64 Seat Adjuster Switch.
2. Test for infinite resistance between the ground terminal and each lumbar signal 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 ground terminal and each lumbar signal 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. All OK.
Lumbar Support Motor
1. Ignition OFF, disconnect the harness connector at the appropriate M53 Seat Lumbar Support Motor.
Note: When performing the following tests, make sure that the lumbar support 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 lumbar motor should momentarily perform the appropriate FORWARD/ REARWARD function.
• If the motor does not perform the FORWARD/ REARWARD function
Replace the M53 Seat Lumbar Support Motor.
• If the motor performs the FORWARD/ REARWARD function
4. Reverse the jumper wires; the lumbar motor should perform FORWARD/ REARWARD function.
• If the motor does not perform the FORWARD/ REARWARD function
Replace the M53 Seat Lumbar Support Motor.
• If the motor performs the FORWARD/ REARWARD 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
* Seat Lumbar Sub System Replacement Seat Lumbar Sub System Replacement