GM Service Manual Online
For 1990-2009 cars only

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

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+ Park Enable Relay

1

1

--

--

B+ Folding Seat Switch

1

2, 4

--

--

B+ Folding Seat Motor - Left

1

3

--

--

B+ Folding Seat Motor - Right

1

3

--

--

Switch Signal

1

3, 4

--

--

Park Enable PCB Relay Control

--

--

1

--

Ground - Folding Seat Motor

--

3

--

--

1. Both seats are inoperative from the front and rear switches

2. Both seats are inoperative from the front switch

3. One seat inoperative from both switches

4. One seat inoperative from one switch

Circuit/System Description

The power fold and tumble second row seats are operated from the power fold switches in the overhead console or the rear switches on the panels behind the rear doors. Voltage to the power fold switches is supplied through the park enable relay while in a de-energized state. The park enable relay is controlled by the body control module (BCM) through a high side drive control circuit and will be energized whenever the ignition is in the accessory, run, or crank positions and the transmission is not in park. The folding seat motors are supplied battery voltage from the REAR SEAT 20A fuse and grounded at the B pillars. When a folding seat switch is pressed, battery voltage is applied through the switch signal circuit to the power fold seat motor. In response to this signal, the folding seat motor will move the seat cushion to folded seat position.

Reference Information

Schematic Reference

Rear 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

Ignition ON with the transmission in the park position, one at a time, operate the left and right rear folding seats using the front and rear folding seat switches. The appropriate rear folding seat should move to the folded position.

If both rear folding seats are inoperative, refer to Power Rear Folding Seats Inoperative.
If one or both folding seat is inoperative from just one switch, refer to Folding Seat Switch Circuit Test.
If one of the folding seats is inoperative from both the front and rear folding seat switches, refer to Folding Seat Motor Circuit Test.

Circuit/System Testing

Power Rear Folding Seats Inoperative

  1. Disconnect the harness connector at either one of the folding seat motors.
  2. Verify that a test lamp illuminates between the B+ circuit terminal A and ground.
  3. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  4. Ignition OFF, disconnect the X2 harness connector at the left instrument panel (I/P) junction block.
  5. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal E2 and ground.
  6. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the EAP fuse #73 is open, test the B+ circuits terminal 1 X8 and terminal 4 X12 for a short to ground.
  7. With the transmission in the PARK position, verify that a test lamp does not illuminate between the control circuit terminal E3 and ground.
  8. If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, refer to the BCM.
  9. Ignition OFF, connect the X2 harness connector at the left I/P junction block. and disconnect the harness connector at the front folding seat switch.
  10. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 1 and ground.
  11. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit tests normal, replace the left I/P junction Block.

Folding Seat Switch Circuit Test

  1. Disconnect the harness connector at the inoperative rear folding seat switch.
  2. Verify that a test lamp illuminates between the appropriate B+ circuit listed below and ground:
  3. • Front Rear Folding Seat Switch terminal 1
    • Left or Right Rear Folding Seat Switch terminal C
    If the test lamp does not illuminate test the switch supply circuit for an open or high resistance. If the circuit tests normal replace the left I/P junction block.
  4. If the circuits test normal, test or replace the folding seat switch.

Folding Seat Motor Circuit Test

  1. Ignition OFF, disconnect the harness connector at the inoperative rear folding seat motor.
  2. Test for less than 5 ohms between the ground circuits listed below and ground:
  3. • Terminal B
    • Terminal D
    If greater than the specified range, test the ground circuit for an open or high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal A and ground.
  5. If the test lamp does not illuminate, test the B+ circuit for an open or high resistance.
  6. Connect a test lamp between the signal circuit terminal C and ground.
  7. The test lamp should illuminate while pressing the appropriate rear folding seat switch.
  8. If the test lamp does not illuminate, test the signal circuit for an open or high resistance.
  9. If all circuits test normal, test or replace the folding seat motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Rear Seat Recliner Switch Replacement - Overhead Console
    •  Rear Seat Recliner Switch Replacement - Lock Pillar Trim
    •  Rear Seat Recliner Actuator Replacement
    •  Instrument Panel Electrical Center or Junction Block Replacement - Left Side