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Home >> Ford Truck >> 2012 >> Explorer FWD L4-2.0L Turbo >> Repair and Diagnosis >> Body and Frame >> Seats >> Testing and Inspection >> Pinpoint Tests >> Seating - 3rd Row >> Diagnostic Routine A

Diagnostic Routine A




Diagnostic Routine A

Diagnostic Overview

Seat Latch Motor and Latch Switch Functional Test - LH

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 seat latch release motor to electronically release the seat latch from the latched position (seat folded and latched to the floor) when the third row seat control switch sends a signal to the PFSM (Power-Fold Seat Module) to move the seat to the STOW position. The PFSM (Power-Fold Seat Module) monitors the latch switch to determine if the position of the latch is closed or released. If the seat latch does not release, the latch must be mechanically released to move the seat from the latched home position. If a fault is detected during a seat operation, the seat may enter a faulted state. When the seat is in a faulted state, the seat backrest and cushion fold together to prevent the seat from being occupied.

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

NOTICE: Do not carry out this pinpoint test unless directed to do so from the Symptom Chart: Seating - Power-Fold Preliminary Inspection.

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 FOR AUDIBLE SEAT LATCH OPERATION

1. Select the LH (Left Hand) seat switch position and press the NORMAL or FOLD button.

2. Press the STOW button and observe and listen for latch motor operation.

Does the latch motor operate or is it audible?








2. CHECK THE PFSM (Power-Fold Seat Module) FOR OUTPUT VOLTAGE TO THE LH (Left Hand) SEAT LATCH 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). If necessary, to release an inoperative latch or to reposition an inoperative power-stow motor, 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 necessary, 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?








3. CHECK THE LH (Left Hand) SEAT LATCH MOTOR CIRCUITS FOR AN OPEN

1. Disconnect: PFSM (Power-Fold Seat Module) C4250A.

2. Disconnect: LH (Left Hand) Latch Motor.

- To access the LH (Left Hand) latch motor connector, REFER to Seat Latch - Power .

3. Measure:





Are the resistances less than 3 ohms?








4. CHECK THE LH (Left Hand) SEAT LATCH MOTOR AND CIRCUIT FOR A SHORT TO GROUND

1. Disconnect: PFSM (Power-Fold Seat Module) C4250A.

2. Measure:





Is the resistance greater than 10,000 ohms?








5. CHECK THE LH (Left Hand) SEAT LATCH MOTOR CIRCUIT FOR A SHORT TO GROUND

1. Disconnect: LH (Left Hand) Latch Motor.

- To access the LH (Left Hand) latch motor connector, REFER to Seat Latch - Power .

2. Measure:





Is the resistance greater than 10,000 ohms?








6. CHECK THE LH (Left Hand) SEAT LATCH SWITCH AND CIRCUITS FOR A SHORT TO GROUND

1. Disconnect: PFSM (Power-Fold Seat Module) C4250A.

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

2. With the latch released, measure:





Is the resistance greater than 10,000 ohms?








7. CHECK THE LH (Left Hand) SEAT LATCH SWITCH CIRCUITS FOR A SHORT TO GROUND OR SHORT TOGETHER

1. Disconnect: LH (Left Hand) Latch Switch.

- To access the LH (Left Hand) latch switch connector, REFER to Seat Latch - Power .

2. Measure:









Are the resistances greater then 10,000 ohms?








8. CHECK THE LH (Left Hand) SEAT LATCH SWITCH AND CIRCUITS FOR AN OPEN

1. Use a suitable tool and manually lock the latch.

2. With the latch locked, measure:





Is the resistance less than 3 ohms?








9. CHECK THE LH (Left Hand) SEAT LATCH SWITCH CIRCUITS FOR AN OPEN

1. Disconnect: LH (Left Hand) Latch Switch.

- To access the LH (Left Hand) latch switch connector, REFER to Seat Latch - Power .

2. Measure:





Are the resistances less than 3 ohms?








10. CHECK THE LH (Left Hand) SEAT LATCH SWITCH CIRCUIT FOR VOLTAGE AT THE PFSM (Power-Fold Seat Module)

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) C4250A.

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 to release the latch and measure the voltage.

Is the voltage greater than 11 volts when the STOW button is pressed?








11. IDENTIFY THE SEAT FUNCTION(S) USING THE TABLE AND DETERMINE THE DIAGNOSTIC DIRECTION

1. Reconnect all disconnected electrical connectors.

2. Operate the seat to each position (NORMAL, STOW, and FOLD) allowing the seat to complete each selection and note all resulting seat movements and seat positions obtained.

3. Compare the step results to the table and determine the diagnostic direction.





Does the seat operate correctly?








12. 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?







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