Pinpoint Tests BU: Seat Latch Motor And Latch Switch Functional Tests - LH Third Row Power Seat
Seats
Pinpoint Test BU: Seat Latch Motor and Latch Switch Functional Test - LH Third Row Power Seat
Refer to Wiring Diagram Set 120, Power Seats for schematic and connector information. Diagrams By Number
Normal Operation
The Power-Fold Seat Module (PFSM) 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 to move the seat to the STOW or TAILGATE position. The PFSM 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 will fold together to prevent the seat from being occupied.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Latch release motor and switch
- PFSM
PINPOINT TEST BU: SEAT LATCH MOTOR AND LATCH SWITCH FUNCTIONAL TEST - LH THIRD ROW POWER SEAT
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. 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.
NOTE: Verify good battery condition before diagnosing the Power-Fold Seat Module (PFSM) system. Poor battery condition may interfere with PFSM 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 accessory delay system (courtesy lamps) 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 accessory delay system during diagnosis and testing, close and open any vehicle door.
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BU1 CONFIRM THE FUNCTIONAL TEST HAS BEEN COMPLETED
- Verify the Functional Test - Third Row Power Seat has been completed before testing the latch assembly.
- Has the Functional Test been completed?
Yes
GO to BU2.
No
CARRY OUT the Functional Test - Third Row Power Seat. GO to Pinpoint Test BT and return to this test only if directed to do so. Pinpoint Tests BT: Functional Tests - Third Row Power Seat
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BU2 CHECK FOR AUDIBLE SEAT LATCH OPERATION
- Select the LH seat switch position and press the NORMAL or FOLD button.
- Press the STOW button and observe and listen for latch motor operation.
- Does the latch motor operate or is audible?
Yes
GO to BU7.
No
GO to BU3.
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BU3 CHECK THE PFSM FOR OUTPUT VOLTAGE TO THE SEAT LATCH MOTOR
- Access the PFSM. If necessary, to release an inoperative latch or to reposition an inoperative power-stow motor, refer to the appropriate steps in Power-Fold Seat Module (PFSM) Power-Fold Seat Module (PFSM).
- Verify the vehicle is in PARK and the liftgate is open.
- Verify the courtesy lights are on. If needed, close and open any door on the vehicle.
- Connect a test lamp between C4250A pin 3 and pin 6 by back-probing the connector.
- Press the STOW button and monitor the test lamp.
- Does the test lamp illuminate momentarily when the STOW button is pressed?
Yes
GO to BU4.
No
GO to BU5.
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BU4 CHECK THE SEAT LATCH MOTOR CIRCUITS FOR AN OPEN
- Disconnect: PFSM C4250A.
- Disconnect: LH Latch Motor C4243.
- To access to the LH latch motor connector, refer to the appropriate steps in Seat Latch - Third Row, Power Seat Latch - Third Row, Power.
- Measure the resistance between:
- PFSM C4250A-3, circuit CPS05 (BU/WH), harness side and LH latch motor C4243-1, circuit CPS74 (VT/WH), harness side.
- PFSM C4250A-6, circuit CPS04 (YE/OG), harness side and LH latch motor C4243-2, circuit CPS04 (YE/OG), harness side.
- Are the resistances less than 5 ohms?
Yes
INSTALL a new power seat latch. REFER to Seat Latch - Third Row, Power Seat Latch - Third Row, Power. TEST the system for normal operation.
No
REPAIR the circuit(s). TEST the system for normal operation.
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BU5 CHECK THE SEAT LATCH MOTOR AND CIRCUIT FOR A SHORT TO GROUND
- Disconnect: PFSM C4250A.
- Measure the resistance between PFSM C4250A-3, circuit CPS05 (BU/WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to BU13.
No
GO to BU6.
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BU6 CHECK THE SEAT LATCH MOTOR CIRCUIT FOR A SHORT TO GROUND
- Disconnect: LH Latch Motor C4243.
- To access to the LH latch motor connector, refer to the appropriate steps in Seat Latch - Third Row, Power Seat Latch - Third Row, Power.
- Measure the resistance between PFSM C4250A-3, circuit CPS05 (BU/WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
INSTALL a new power seat latch. Refer to Seat Latch - Third Row, Power Seat Latch - Third Row, Power. TEST the system for normal operation.
No
REPAIR the circuit. TEST the system for normal operation.
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BU7 CHECK THE SEAT LATCH SWITCH AND CIRCUITS FOR A SHORT TO GROUND
- Disconnect: PFSM C4250A.
- To access the PFSM, refer to the appropriate steps in Power-Fold Seat Module (PFSM) Power-Fold Seat Module (PFSM).
- With the latch released, measure the resistance between PFSM C4250A-13, circuit CPS56 (GN/BN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to BU9.
No
GO to BU8.
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BU8 CHECK THE SEAT LATCH SWITCH CIRCUITS FOR A SHORT TO GROUND OR SHORT TOGETHER
- Disconnect: LH Latch Switch C4241.
- To access to the LH latch switch connector, refer to the appropriate steps in Seat Latch - Third Row, Power Seat Latch - Third Row, Power.
- Measure the resistance between:
- PFSM C4250A-13, circuit CPS56 (GN/BN), harness side and ground.
- PFSM C4250A-13, circuit CPS56 (GN/BN), harness side and PFSM C4250A-12, circuit CPS51 (VT/GY), harness side.
- Are the resistances greater then 10,000 ohms?
Yes
INSTALL a new power seat latch. REFER to Seat Latch - Third Row, Power Seat Latch - Third Row, Power. TEST the system for normal operation.
No
REPAIR the circuit(s). TEST the system for normal operation.
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BU9 CHECK THE SEAT LATCH SWITCH AND CIRCUITS FOR AN OPEN
- Use a suitable tool and manually lock the latch.
- With the latch locked, measure the resistance between PFSM C4250A-13, circuit CPS56 (GN/BN), harness side and PFSM C4250A-12, circuit CPS51 (VT/GY), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to BU11.
No
GO to BU10.
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BU10 CHECK THE SEAT LATCH SWITCH CIRCUITS FOR AN OPEN
- Disconnect: LH Latch Switch C4241.
- To access to the LH latch switch connector, refer to the appropriate steps in Seat Latch - Third Row, Power Seat Latch - Third Row, Power.
- Measure the resistance between:
- PFSM C4250A-13, circuit CPS56 (GN/BN), harness side and LH latch switch C4241-1, circuit CPS57 (GY/BN), harness side.
- PFSM C4250A-12, circuit CPS51 (VT/GY), harness side and LH latch switch C4241-2, circuit CPS51 (VT/GY), harness side.
- Are the resistances less than 5 ohms?
Yes
INSTALL a new power seat latch. REFER to Seat Latch - Third Row, Power Seat Latch - Third Row, Power. TEST the system for normal operation.
No
REPAIR the circuit(s). TEST the system for normal operation.
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BU11 CHECK THE SEAT LATCH SWITCH CIRCUIT FOR VOLTAGE AT THE PFSM
- Connect: PFSM C4250A.
- Verify the vehicle is in PARK and the liftgate is open.
- Verify the courtesy lights are on. If needed, close and open any door on the vehicle.
- Back-probe PFSM C4250A and measure the voltage between PFSM C4250A-13, circuit CPS56 (GN/BN), and PFSM C4250A-12, circuit CPS51 (VT/GY).
- Press the STOW button to release the latch and measure the voltage.
- Is the voltage greater than 10 volts?
Yes
The latch assembly checks OK. GO to BU12.
No
GO to BU13.
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BU12 IDENTIFY THE SEAT FUNCTION(S) USING THE TABLE AND DETERMINE THE DIAGNOSTIC DIRECTION
- Reconnect all disconnected electrical connectors.
- Operate the seat to each position (NORMAL, STOW, FOLD and TAILGATE) allowing the seat to complete each selection and note all resulting seat movements and seat positions obtained.
- Compare the step results to the table and determine the diagnostic direction.
- Does the seat operate correctly?
Yes
The fault is not present and cannot be recreated at this time. Do not install any new components at this time. Components should only be installed when directed to do so in the pinpoint test. GO to BU13.
No
To check the power-stow seat motor, stow sensor and circuits, GO to Pinpoint Test BW. Pinpoint Tests BW: Power-Stow Seat Motor And Sensor Functional Tests - LH Third Row Power Seat
To check the power-fold seat motor (backrest), fold sensor and circuits, GO to Pinpoint Test BY. Pinpoint Tests BY: Power-Fold Seat Motor (Backrest) And Sensor Functional Tests - LH Third Row Power Seat
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BU13 CHECK PFSM CONNECTORS AND PINS FOR DAMAGE AND RETEST THE SYSTEM
- Inspect the PFSM connectors for corrosion and pushed out or damaged pins and repair as necessary.
- Reconnect all the PFSM connectors.
- Operate the seats and determine if the concern is still present.
- Is the concern still present?
Yes
INSTALL a new PFSM. Refer to Power-Fold Seat Module (PFSM) Power-Fold Seat Module (PFSM). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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