Liftgate Window Release Inoperative

Liftgate Window Release Inoperative

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information






Circuit/System Description

The liftglass release switch is an input to the body control module (BCM). The BCM supplies battery voltage to the signal circuit and when the release switch is activated the signal circuit voltage goes low. The BCM controls the liftglass release actuator through the rear wiper motor control module. When the release switch signal is activated, the BCM applies battery voltage as a signal through the liftglass latch release control circuit to the rear wiper motor control module. The rear wiper motor control module supplies voltage to the release actuator through the liftglass latch assembly.

Reference Information
Schematic Reference

Release Systems Schematics Release Systems Schematics
Connector End View Reference

Component Connector End Views Connector Views
Description and Operation

Liftgate Description and Operation Liftgate
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, command the rear window wiper ON and OFF by using the rear wiper switch. The rear window wiper should turn ON and OFF when changing between commanded states.

• If the rear window wiper does not turn ON and OFF, refer to Rear Wiper System Malfunction Rear Wiper System Malfunction

2. Observe the scan tool Ext. Trunk/Liftglass Rel. Sw parameter while pressing the liftgate window release switch. The parameter should change from Inactive to active.

• If the parameter does not change, refer to Liftglass Release Switch Malfunction.

3. Command the liftglass latch to release the liftglass by pressing the liftgate window release switch. The liftglass latch should release the liftglass.

• If the liftglass latch does not release the liftglass, refer to Liftglass Latch Assembly Malfunction.

Circuit/System Testing

Liftglass Release Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the liftglass release switch.
2. Test for less than 5 Ohms between the ground circuit terminal B and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Ext. Trunk/Liftglass Rel. Sw parameter is Inactive.

• If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the BCM.

4. Connect a 3A fused jumper wire between the signal circuit terminal A and ground, verify the scan tool Ext. Trunk/Liftglass Rel. Sw 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 BCM.

5. If all circuits test normal, test or replace the liftglass release switch.

Liftglass Latch Assembly Malfunction
1. Ignition OFF, disconnect the harness connector at the rear window wiper motor.
2. Ignition ON, connect a test lamp between the signal circuit terminal B and ground.
3. Command the liftglass latch to release by pressing the liftgate window release switch. The test lamp should briefly illuminate when the liftgate window release switch is pressed.

• If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

• If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.

4. Ignition OFF, connect the harness connector at the rear window wiper motor. Disconnect the harness connector at the liftglass latch assembly.
5. Test for less than 5 Ohms between the ground circuit terminal 2 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

6. Ignition ON, connect a test lamp between the control circuit terminal 1 and ground.
7. Command the liftglass latch to release by pressing the liftgate window release switch. The test lamp should briefly illuminate when the liftgate window release switch is pressed.

• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal replace the rear window wiper motor.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal replace the rear window wiper motor.

8. If all circuits test normal, test or replace the liftglass latch assembly.

Component Testing

Liftglass Latch Assembly
1. Ignition OFF, disconnect the harness connector at the rear liftglass latch assembly.
2. Install a 20A fused jumper wire between the control terminal 1 and 12 volts. Install a jumper wire between the ground terminal 2 and ground. Verify the liftglass actuator activates.

• If the actuator does not perform as specified, replace the liftglass latch assembly.

Liftglass Release Switch
1. Ignition OFF, disconnect the harness connector at the liftglass release switch.
2. Test for infinite resistance between the signal terminal A and the ground terminal B with the switch in the open position.

• If not the specified value, replace the liftglass release switch.

3. Test for less than 2 Ohms between the signal terminal A and the ground terminal B with the switch in the closed position.

• If greater than the specified range, replace the liftglass release switch.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Liftgate Window Latch Replacement Liftgate Window Latch Replacement
* Rear Window Wiper Motor Replacement Rear Window Wiper Motor Replacement
* Control Module References Control Module References for BCM replacement, setup, and programming