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Power Liftgate Inoperative



POWER LIFTGATE INOPERATIVE

DIAGNOSTIC INSTRUCTIONS
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
- 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/SYSTEM DESCRIPTION
The power liftgate module (PLGM) controls operation of the liftgate latch motor and the liftgate actuator assembly. Under normal conditions the power latch can only be unlatched under power from the PLGM through an input from the liftgate handle switch, the instrument panel switch, or the remote keyless entry (RKE) transmitter, but the liftgate may be manually closed to the primary latched position without the PLGM performing the power latch function. The ON/OFF switch in the instrument panel switchbank will enable or disable the power open/close operation of the actuator assembly but will have no effect on power latch operation. The liftgate actuator assembly consists of the actuator drive motor with 2 internal Hall effect sensors. The drive motor is mated to a worm type gear off the actuator clutch and when the clutch is engaged the motor rotation is transferred to the clutch gear, intermediate gear, and actuator arm gear. The full open switch is a limit switch mounted on the liftgate actuator assembly along side the actuator arm gear, and will make contact with the cam on the actuator arm gear when the liftgate is near the full open position. The PLGM continuously monitors the liftgate location and direction of travel using the 2 Hall effect sensors in the drive motor. The sensor counts are used to determine when the liftgate has reached the open and closed points of travel where the actuator clutch should be disengaged. These positions may vary slightly and must be learned when most liftgate components are serviced.

DIAGNOSTIC AIDS
Power liftgate function will only be allowed if certain operating criteria are met. Any of the following may cause the power liftgate not to function:
- After a power loss of the low current battery supply until the ignition is cycled.
- Vehicle is not in park.
- Engine cranking is present.
- Ambient temperature at the PLGM must be within -17 to +80°C (+1 to +176°F).
- Liftgate motor excess current is detected.
- System voltage is out of range.
- A DTC is set that disables power liftgate functionality.
- The liftgate is locked when attempting to open from exterior handle.
- The theft deterrent system is enabled.
The liftgate also receives input from 2 pressure sensing object detection sensors. If either of these sensors indicates an object may be pinched as the liftgate is brought to the closed position, the liftgate will reverse direction and power close operation will be suspended until the pressure against the sensor is released.

CIRCUIT/SYSTEM VERIFICATION
1. Ignition ON, doors unlocked, transaxle in Park, disable the power liftgate by pressing the Liftgate Enable/Disable button on the I/P Switch Assembly.
2. Open the liftgate by pressing the touchpad on the liftgate handle switch and close by pushing the liftgate closed. The liftgate should release, cinch-in and latch.
- If the liftgate fails to release, cinch-in or latch, refer to Latch Assembly Malfunction.
3. Enable the liftgate by pressing the Enable/Disable button on the I/P Switch Assembly and command the liftgate to OPEN and CLOSE with a scan tool. The liftgate should OPEN and CLOSE as commanded.
- If the liftgate fails to OPEN and CLOSE, refer to Power Liftgate Inoperative.
- If the liftgate closes and immediately reopens, refer to Liftgate Closes and Reopens
4. Command the Power Liftgate to OPEN and CLOSE by pressing the I/P Switch Assembly, the liftgate should OPEN and CLOSE as commanded.
- If the liftgate does not OPEN and CLOSE as commanded, refer to I/P Switch Inoperative.
5. Command the Power Liftgate to OPEN by pressing the touchpad on the Liftgate Handle, the liftgate should OPEN as commanded.
- If the liftgate does not OPEN as commanded, refer to Liftgate Handle Switch Inoperative.
6. Command the Power Liftgate to Close by pressing the liftgate button next to the liftgate latch, the liftgate should CLOSE as commanded.
- If the liftgate does not CLOSE as commanded, refer to Liftgate Button Switch Inoperative.

CIRCUIT/SYSTEM TESTING

Latch Assembly Malfunction
1. Ignition OFF, disconnect the harness connector at the Liftgate Latch Assembly.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the Release control circuit terminal 1 and ground.
- If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the PLGM.
3. Ignition OFF, test for less than 1.0 ohm of resistance between the Cinch control circuit terminal 3 and ground.
- If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the PLGM.
4. Connect a test lamp between control circuit terminal 1 and control circuit terminal 3.
5. Command the Liftgate to OPEN and CLOSE with a scan tool. The test lamp should turn ON when commanding the OPEN and CLOSE states.
- If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, replace the PLGM.
6. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 2 and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the PLGM.
7. Ignition ON, verify the scan tool Pawl Sw. parameter is INACTIVE.
- If not the specified value, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the PLGM.
8. Ignition ON, verify the scan tool Ratchet Sw. parameter is INACTIVE.
- If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the PLGM.
9. Ignition ON, verify the scan tool Sector Sw. parameter is INACTIVE.
- If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the PLGM.
10. Install a 3A fused jumper wire between the signal circuit terminal 5 and low reference circuit terminal 2. Verify the scan tool Pawl Sw. parameter is ACTIVE.
- If not the specified value, test the signal circuit terminal 5 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PLGM.
11. Install a 3A fused jumper wire between the signal circuit terminal 6 and low reference circuit terminal 2. Verify the scan tool Ratchet Sw. parameter is ACTIVE.
- If not the specified value, test the signal circuit terminal 6 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PLGM.
12. Install a 3A fused jumper wire between the signal circuit terminal 4 and low reference circuit terminal 2. Verify the scan tool Sector Sw. parameter is ACTIVE.
- If not the specified value, test the signal circuit terminal 4 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PLGM.
13. If all circuits test normal, test or replace the Liftgate Latch Assembly.

Power Liftgate Inoperative
1. Ignition OFF, disconnect the harness connector at the PLGM.
2. Ignition OFF, test for 1.0 ohm of resistance between the ground terminal 6 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 3 and ground.
- 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 PWR L/GATE fuse is open, replace the PLGM.

Liftgate Closes and Reopens
1. Ignition OFF, disconnect the harness connector at the appropriate liftgate object sensor.
2. Ignition OFF, test for 10 ohms of resistance between the signal terminal B and the low reference circuit terminal A.
- If less than the specified range, replace the appropriate liftgate object sensor. If the circuit tests normal, replace the PLGM.

I/P Switch Inoperative
1. Ignition OFF, disconnect the harness connector at the I/P switch assembly.
2. Ignition OFF, test for less than 1 ohm of resistance between the ground circuit terminal 3 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool PLGM Disable Switch parameter is Inactive.
- If not the specified value, test the signal circuit terminal 8 for a short to ground. If the circuit tests normal, replace the PLGM.
4. Install a 3A fused jumper wire between the signal circuit terminal 8 and ground. Verify the scan tool PLGM Disable Switch parameter is Active.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PLGM.
5. Verify the scan tool Front Control Switch parameter is Inactive.
- If not the specified value, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the PLGM.
6. Install a 3A fused jumper wire between the signal circuit terminal 7 and ground. Verify the scan tool Front Control Switch parameter is Active.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PLGM.
7. If all circuits test normal, test or replace the I/P switch.

Liftgate Handle Switch Inoperative
1. Ignition OFF, disconnect the harness connector at the exterior liftgate switch.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal 2 and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Liftgate Handle Sw Status parameter is Inactive.
- If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the PLGM.
4. Install a 3A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Liftgate Handle Sw Status parameter is Active.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PLGM.
5. If all circuits test normal, test or replace the exterior liftgate switch.

Liftgate Button Switch Inoperative
1. Ignition OFF, disconnect the harness connector at the interior liftgate switch.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal 2 and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Liftgate Handle Sw Status parameter is Inactive.
- If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the PLGM.
4. Install a 3A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Liftgate Handle Sw Status parameter is Active.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PLGM.
5. If all circuits test normal, test or replace the interior liftgate switch.

COMPONENT TESTING
Liftgate Object Sensor
1. Ignition OFF, disconnect the harness connector at the right liftgate tape switch.
2. Test for 10K ohms of resistance between the signal terminal A and the low reference terminal B.
- If not within the specified range, replace the right liftgate tape switch.
3. Disconnect the harness connector at the left liftgate tape switch.
4. Test for 10K ohms of resistance between the signal terminal A and the low reference terminal B.
- If resistance is not within the specified range, replace the left liftgate tape switch.

Liftgate Interior/Exterior Switch
1. Ignition OFF, disconnect the harness connector at the appropriate Liftgate Switch.
2. Test for infinite resistance between the signal terminal 1 and the low reference circuit terminal 2 with the switch in the open position.
- If not the specified value, replace the appropriate Liftgate Switch.
3. Test for less than 2.0 ohms between the signal terminal 1 and the low reference circuit terminal 2 with the switch in the closed position.
- If greater than the specified range, replace the appropriate Liftgate Switch.

Liftgate Latch Assembly
1. Install a 20-amp fused jumper wire between the control terminal 1 and 12 volts. Momentarily install a jumper wire between the control terminal 3 and ground. The Liftgate Latch Assembly should perform the CINCH or RELEASE function.
- If the function does not perform as specified, replace the Liftgate Latch Assembly.
2. Reverse the jumper wires, the Liftgate Latch Assembly should perform the RELEASE or CINCH function.
- If the function does not perform as specified, replace the Liftgate Latch Assembly.

I/P Switch Assembly
1. Ignition OFF, disconnect the harness connector at the I/P Switch Assembly.
2. Test for infinite resistance between the signal circuit terminal 7 and the ground circuit terminal 3 with the liftgate open switch in the inactive position.
- If not the specified value, replace the I/P Switch Assembly.
3. Test for infinite resistance between the signal circuit terminal 8 and the ground circuit terminal 3 with the liftgate disable switch in the inactive position.
- If not the specified value, replace the I/P Switch Assembly.
4. Test for less than 3 ohms between the signal circuit terminal 7 and the ground circuit terminal 3 with the liftgate open switch in the active position.
- If greater than the specified range, replace the I/P Switch Assembly.
5. Test for less than 3 ohms between the signal circuit terminal 8 and the ground circuit terminal 3 with the switch in the disable position.
- If greater than the specified range, replace the I/P Switch Assembly.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
- Control Module References for BCM replacement, setup, and programming. Programming and Relearning
- Liftgate Calibration Procedure
- Liftgate Outside Handle Replacement
- Power Liftgate Motor Replacement
- Liftgate Side Upper Sensor Replacement
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