Diagnostic Routine D

Diagnostic Routine D

Diagnostic Overview

Power-Stow Seat Motor and Sensor Functional Test - RH

Refer to Wiring Diagram Set 120 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

The PFSM (Power-Fold Seat Module) supplies voltage and ground to the power-stow seat motor to move the seat to and from the STOW position when selected by the seat control switch. When STOW is selected from NORMAL, the backrest folds forward to release the spring loaded headrest. If an obstruction is detected in the STOW range of movement, the seat stops, reverses movement a few inches and then stops again until the obstruction is removed. When the obstruction has been removed, the seat control switch must be pressed again to reset the request. The seat goes to the power-stow seat motor home position (seat folded and latched to the floor) and then continues with the STOW request. If the PFSM (Power-Fold Seat Module) detects an open or short in the power-stow seat motor circuitry, motor operation is disabled. If a short to ground is present, the motor works in only one direction.

A Hall-effect sensor is located inside each of the power-stow seat motor assemblies to detect power-stow seat motor movement and position to the PFSM (Power-Fold Seat Module). If the sensor does not detect motor movement during a request from the seat control switch, the PFSM (Power-Fold Seat Module) disables the power-stow seat motor output. When the seat control switch is pressed again, the seat moves in short increments indicating a fault with the sensor or circuitry.

Visual Inspection and Diagnostic Pre-checks

Verify good battery condition before diagnosing the PFSM (Power-Fold Seat Module) system. Poor battery condition may interfere with PFSM (Power-Fold Seat Module) operation. If battery voltage drops below 10 volts, seat movement does not start. If battery voltage drops below 8 volts, a started seat movement stops.

Pinpoint Test

NOTE: Verify good battery condition before diagnosing the PFSM (Power-Fold Seat Module) system. Poor battery condition may interfere with PFSM (Power-Fold Seat Module) operation. If battery voltage drops below 10 volts, seat movement will not start. If battery voltage drops below 8 volts, a started seat movement will stop.

NOTE: The battery saver relay system will time-out after 10 minutes and disable the third row power seat operation. Meter voltage measurements will be inaccurate when this occurs, which could lead to misdiagnosis. To enable the battery saver relay system during diagnosis and testing, close and open any vehicle door.

1. CHECK THE PFSM (Power-Fold Seat Module) FOR OUTPUT VOLTAGE TO THE POWER-STOW SEAT MOTOR
NOTICE: The following pinpoint test uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.

NOTICE: This pinpoint test step directs testing circuits using a back-probe method. Use the special back-probe tool specified in the tool list. Do not force test leads or other probes into connectors. Adequate care must be exercised to avoid connector terminal damage while making sure that good electrical contact is made with the circuit or terminal. Failure to follow these instructions may cause damage to wiring, terminals, or connectors and subsequent electrical faults.

1. Access the PFSM (Power-Fold Seat Module). To access the PFSM (Power-Fold Seat Module), REFER to Power-Fold Seat Module (PFSM) .

2. Verify the vehicle is in PARK and the liftgate is open.

3. Verify the courtesy lights are on. If needed, close and open any door on the vehicle.

4. Measure:





5. Press the STOW button and monitor the test light.

Does the test light illuminate momentarily when the STOW button is pressed?








2. CHECK THE RH (Right Hand) POWER-STOW SEAT MOTOR AND CIRCUITS FOR A SHORT TO GROUND

1. Disconnect: PFSM (Power-Fold Seat Module) C4250C.

2. Measure:





Are the resistances greater than 10,000 ohms?








3. CHECK THE RH (Right Hand) POWER-STOW SEAT MOTOR AND CIRCUITS FOR A SHORT TO GROUND

1. Disconnect: RH (Right Hand) Power-Stow Seat Motor.

- Remove the rear quarter trim finish panel to access the RH (Right Hand) power-stow seat motor electrical connector. REFER to Quarter Trim Panel - With Inflatable Safety Belts or REFER to Quarter Trim Panel - Without Inflatable Safety Belts .

2. Measure:





Are the resistances greater than 10,000 ohms?








4. CHECK THE RH (Right Hand) POWER-STOW SEAT MOTOR AND CIRCUITS FOR AN OPEN

1. Disconnect: PFSM (Power-Fold Seat Module) C4250C.

2. Measure:





Is the resistance less than 5 ohms?








5. CHECK THE RH (Right Hand) POWER-STOW SEAT MOTOR CIRCUITS FOR AN OPEN

1. Disconnect: RH (Right Hand) Power-Stow Seat Motor.

- Remove the rear quarter trim finish panel to access the RH (Right Hand) power-stow seat motor electrical connector. REFER to Quarter Trim Panel - With Inflatable Safety Belts or REFER to Quarter Trim Panel - Without Inflatable Safety Belts .

2. Measure:





Are the resistances less than 3 ohms?








6. CHECK THE PFSM (Power-Fold Seat Module) FOR OUTPUT VOLTAGE TO THE STOW SENSOR
NOTICE: This pinpoint test step directs testing circuits using a back-probe method. Use the special back-probe tool specified in the tool list. Do not force test leads or other probes into connectors. Adequate care must be exercised to avoid connector terminal damage while making sure that good electrical contact is made with the circuit or terminal. Failure to follow these instructions may cause damage to wiring, terminals, or connectors and subsequent electrical faults.

1. Connect: PFSM (Power-Fold Seat Module) C4250C.

2. Verify the vehicle is in PARK and the liftgate is open.

3. Verify the courtesy lights are on. If needed, close and open any door on the vehicle.

4. Measure:





Is the voltage greater than 5 volts?








7. CHECK THE RH (Right Hand) POWER-STOW SEAT MOTOR SENSOR AND CIRCUIT FOR A SHORT TO GROUND

1. Disconnect: PFSM (Power-Fold Seat Module) C4250B.

2. Disconnect: RH (Right Hand) Power-Fold Seat Motor.

- Remove the rear quarter trim finish panel to access the RH (Right Hand) power-fold seat motor electrical connector. REFER to Quarter Trim Panel - With Inflatable Safety Belts or REFER to Quarter Trim Panel - Without Inflatable Safety Belts .

3. Measure:





Is the resistance greater than 10,000 ohms?








8. CHECK THE RH (Right Hand) POWER STOW SEAT MOTOR SENSOR CIRCUIT FOR A SHORT TO GROUND

1. Disconnect: RH (Right Hand) Power-Stow Seat Motor.

- Remove the rear quarter trim finish panel to access the power-stow seat motor electrical connector. REFER to Quarter Trim Panel - With Inflatable Safety Belts or REFER to Quarter Trim Panel - Without Inflatable Safety Belts .

2. Measure:





Are the resistances greater than 10,000 ohms?








9. CHECK THE RH (Right Hand) POWER-STOW SEAT MOTOR SENSOR CIRCUITS FOR AN OPEN

1. Disconnect: RH (Right Hand) Power-Stow Seat Motor.

- Remove the rear quarter trim finish panel to access the power-stow seat motor electrical connector. REFER to Quarter Trim Panel - With Inflatable Safety Belts or REFER to Quarter Trim Panel - Without Inflatable Safety Belts .

2. Disconnect: PFSM (Power-Fold Seat Module) C4250B.

3. Measure:





Are the resistances less than 3 ohms?








10. CHECK PFSM (Power-Fold Seat Module) CONNECTORS AND PINS FOR DAMAGE AND RETEST THE SYSTEM

1. Disconnect and inspect all PFSM (Power-Fold Seat Module) connectors.

2. Repair:

- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins as necessary
- pushed-out pins - install new pins as necessary

3. Reconnect all previously disconnected electrical connectors.

4. Operate the seats and determine if the concern is still present.

Is the concern still present?