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

Back Panel Position Switch Supply Voltage

B1395 03

2

--

--

Load Floor Position Switch Supply Voltage

B1395 03

1

--

--

Back Panel Position Switch Signal

B1395 03

2

1

--

Load Floor Position Switch Signal

B1395 03

1

--

--

Folding Seat Switch B+

1

1

--

--

Folding Seat Front Stow Switch Signal

1

1

B1545 00

--

Folding Seat Recline Switch Signal

1

2

B3729 00

--

Folding Seat Rear Stow Switch Signal

1

1

B1546 00

--

Folding Seat Horizontal Position Sensor Signal

B2375 0A

B2375 0A

B2375 0A

--

Folding Seat Recline Position Sensor Signal

B1825 0A

B1825 0A

B1825 0A

--

Folding Seat Rotation Position Sensor Signal

B1548 0A

B1548 0A

B1548 0A

--

Folding Seat Horizontal Motor Forward Control

B1770 0B

B2375 0A or 1

--

--

Folding Seat Horizontal Motor Rearward Control

B1770 0B

B2375 0A or 1

--

--

Folding Seat Recline Motor Forward Control

B1785 0B

B1825 0A or 1

--

--

Folding Seat Recline Motor Rearward Control

B1785 0B

B1825 0A or 1

--

--

Folding Seat Rotation Motor Forward Control

B1547 0B

B1548 0A or 1

--

--

Folding Seat Rotation Motor Rearward Control

B1547 0B

B1548 0A or 1

--

--

Sensor Low Reference

--

B1548 0A, B1825 0A, B2375 0A

--

--

1. Power Third Row Seat Inoperative

2. Power Third Row Seat Recline Inoperative

Circuit/System Description

With the seat in the seated position, and when a stow switch is pressed, battery positive voltage is applied through the switch signal circuit to the rear seat module (RSM). The RSM then simultaneously commands the rotation motor to rotate the seat back 180 degrees forward and the seat horizontal motor to move the seat cushion forward until it reaches it's end of travel. After seat back rotation and seat horizontal movements are complete, the RSM then commands the recline motor to lower the seat back rearward to the stow position. Moving the seat to the seated position works similarly to moving the seat to the stowed position, except battery positive voltage and ground are applied to the opposite control circuits causing the motors to run in the opposite direction.

Diagnostic Aids

    • The Seat Back Load Floor Position Switch is also referenced as the Seat Back Presence Sensor.
    • The Seat Back Panel Position Switch is also referenced as the Rear Seat Number 2 Folding Actuator Seat Position Switch.

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Ignition ON, verify that the scan tool Rear Seat Module DTCs; B1547, B1395, B1770, and B1785 are not set as history.
  2. If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  3. Observe the scan tool Rear Seat Module Calibrated parameter. The reading should be Yes.
  4. If not the specified value, refer to Power Folding Seat Calibration.
  5. Ignition ON with the right rear door OPEN, observe the scan tool BCM Right Rear Door Ajar Sw. parameter. The reading should be Door Ajar.
  6. If not the specified value, refer to Door Ajar Indicator Malfunction.
  7. Ignition ON with the liftgate OPEN, observe the scan tool Liftgate Module Liftgate Ajar Switch parameter. The reading should be Active.
  8. If not the specified value, refer to Liftgate Ajar Indicator Malfunction.
  9. To enable the RSM place the gear selector in PARK, open the rear liftgate or the right rear passenger door, and perform one of the following procedures:
  10. • Turn the ignition ON.
    • Press the remote control keyless entry transmitter unlock button 3 times within 5 seconds.
    • Press the driver or passenger door lock switch unlock button 3 times within 5 seconds.
  11. Ignition ON, observe the scan tool Rear Seat Module parameters listed below while pressing and releasing the appropriate switch. The reading should change between Inactive and Active.
  12. • Front Stow Switch
    • Rear Stow Switch
    • Recline Switch
    If not the specified value, refer to Folding Seat Switch Malfunction.
  13. Observe the position of the power folding seat.
  14. If the seat is stuck in a position other than the stowed position, refer to Seat Back Panel Position Switch Malfunction.
    If the seat is stuck in the stowed position, refer to Load Floor Position Switch Malfunction.

Circuit/System Testing

Folding Seat Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate folding seat stow switch or recline switch.
  2. Ignition ON, 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. If the circuit tests normal and the B+ circuit fuse is open, test the signal circuit terminal C for a short to ground.
  4. Install a 3A fused jumper wire between the appropriate signal circuit terminal C and the B+ circuit terminal A. Verify the appropriate scan tool parameter listed below is Active:
  5. • Front Stow Switch
    • Rear Stow Switch
    • Recline Switch
    If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace RSM.
  6. If all circuits test normal, test or replace the appropriate folding seat stow or recline switch.

Seat Back Panel Position Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the seat back panel position switch.
  2. Ignition ON, test for B+ between the voltage reference circuit terminal B and ground.
  3. If not the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the RSM.
  4. Verify the scan tool Back Panel Position Switch parameter is Inactive.
  5. If not the specified value, test the signal circuit terminal A for a short to voltage. If the circuit tests normal, replace the RSM.
  6. Install a 3A fused jumper wire between the signal circuit terminal A and the voltage reference circuit terminal B. Verify the scan tool Back Panel Position Switch parameter is Active.
  7. If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the RSM.
  8. If all circuits test normal, test or replace the seat back panel position switch.

Load Floor Position Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the seat back load floor position switch.
  2. Ignition ON, test for B+ between the voltage reference circuit terminal B and ground.
  3. If not the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the RSM.
  4. Verify the scan tool Load Floor Switch parameter is Active.
  5. If not the specified value, test the signal circuit terminal A for a short to voltage. If the circuit tests normal, replace the RSM.
  6. Install a 3A fused jumper wire between the signal circuit terminal A and the voltage reference circuit terminal B. Verify the scan tool Load Floor Switch parameter is Active.
  7. If not the specified value, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the RSM.
  8. If all circuits test normal, test or replace the load floor position switch.

Component Testing

Folding Seat Stow or Recline Switch

  1. Ignition OFF, disconnect the harness connector at the appropriate folding seat stow switch or recline switch.
  2. Test for infinite resistance between the signal terminal C and the B+ terminal A with the switch in the open position.
  3. If not the specified value, replace the folding seat switch.
  4. Test for less than 2 ohms between the signal terminal C and the B+ terminal A with the switch in the closed position.
  5. If greater than the specified range, replace the folding seat switch.

Seat Back Panel Position Switch or Load Floor Position Switch

  1. Ignition OFF, disconnect the harness connector at the appropriate seat back panel position switch or load floor position switch.
  2. Test for infinite resistance between the signal terminal A and the B+ terminal B with the switch in the open position.
  3. If not the specified value, replace the appropriate seat position switch.
  4. Test for less than 2 ohms between the signal terminal A and the B+ terminal B with the switch in the closed position.
  5. If greater than the specified range, replace the appropriate seat position switch.

Repair Instructions

Important: After performing this diagnostic test and electrical or component repairs have been completed, the folding seat may be in an unknown state and out of calibration with the RSM. The RSM must be calibrated before the folding seat system will operate. Refer to Power Folding Seat Calibration.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Rear Seat Number 2 Folding Actuator Switch Replacement - Rear Quarter Trim Rear
    •  Rear Seat Number 2 Folding Actuator Switch Replacement - Rear Quarter Trim Front
    •  Rear Seat Number 2 Seat Back Presence Sensor Replacement
    •  Rear Seat Number 2 Folding Actuator Seat Position Switch Replacement
    •  Control Module References for RSM replacement, setup, and programming