For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | 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 | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Relay Switch B+ | 1, 2 | 1, 2 | -- | --
Rear Closure Handle Switch Open Signal | 1 | 1 | 1 | --
Liftgate Latch Relay Supply Voltage | B3265 | B3265 | B3265 | --
Liftgate Latch Relay Coil Control | B3265 | B3265 | B3265 | --
Liftgate Switch Ground | -- | 1, 2 | 1, 2 | --
Liftgate Latch Ground | -- | 2 | 2 | --
1. Liftgate Release Switch Inoperative 2. Liftgate Release Inoperative

### Circuit/System Description

The liftgate can be released by operating the liftgate release switch or pressing the liftgate release button on the key fob. The gear selector may be in any position, but vehicle must be stationary for the liftgate to release.

Pressing the liftgate switch closes a contact providing a ground for the rear closure handle switch open signal circuit. The BCM will detect the voltage drop and command voltage to be supplied to the liftgate latch relay supply voltage circuit thus energizing the liftgate relay which provides voltage to the liftgate latch releasing the liftgate.

### Reference Information

#### Schematic Reference

Release Systems Schematics

#### Connector End View Reference

Vehicle Access Connector End Views

#### Description and Operation

Rear Hatch/Gate Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Ignition ON, observe the scan tool Int Trunk/Liftglass Sw parameter while pressing and releasing the liftgate switch. The reading should change between Active and Inactive.

⇒ | If the reading does not change as specified, refer to Liftgate Switch Malfunction.

2. Observe the scan tool Trunk Release Solenoid Command parameter while pressing and releasing the liftgate switch. The reading should change between ON and OFF.

⇒ | If the reading does not change as specified, refer to Liftgate Release Malfunction.

### Circuit/System Testing

#### Liftgate Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the liftgate switch.
2. Test for less than 1 ohm for resistance between the ground circuit terminal C and ground.

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

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

⇒ | If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3-A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Int Trunk/Liftglass Sw 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 BCM.

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

#### Liftgate Release Malfunction

1. Ignition OFF, disconnect the harness connector C2 at the I/P fuse block.
2. Connect a test lamp between the B+ circuit terminal 1 and ground.
3. Ignition ON, the test lamp should illuminate.

⇒ | If the test lamp is always OFF and the batt 2 fuse is good, test the B+ circuit for an open/high resistance. If the circuit tests normal, replace the underhood fuse block.

⇒ | If the test lamp is always OFF and the batt 2 fuse is open, test the B+ circuit for a short to ground, if the circuit tests normal, replace the I/P fuse block.

4. Ignition OFF, reconnect the harness connector C2 and disconnect the harness connector C3 at the I/P fuse block.
5. Connect a test lamp between the liftgate latch relay supply voltage circuit terminal 20 and ground.
6. Ignition ON, command the liftgate latch to release by pressing the liftgate switch. The test lamp should turn ON and OFF while pressing and depressing the liftgate switch.

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

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

7. Connect a test lamp between the liftgate latch relay coil control circuit terminal 9 and B+.
8. Command the liftgate latch to release by pressing the liftgate switch. The test lamp should turn ON and OFF while pressing and depressing the liftgate switch.

⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

9. Test for less than 1.0 ohm of resistance between the liftgate latch ground circuit terminal 3 and ground

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

10. Connect a test lamp between the control circuit terminal 1 and ground.
11. Ignition ON, command the liftgate latch to release by pressing the liftgate switch. The test lamp should turn ON and OFF while pressing and depressing the liftgate switch.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the I/P fuse block

⇒ | If the test lamp is always OFF and the l/gate circuit fuse is good, test the control circuit for an open/high resistance, if the circuit tests normal, test or replace the I/P fuse block.

⇒ | If the test lamp is always OFF and the l/gate circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the liftgate latch.

12. If all circuits test normal, test or replace the liftgate latch.

### Component Testing

#### Liftgate Latch

1. Ignition OFF, disconnect the harness connector at the liftgate latch.
2. Install a 15-amp fused jumper wire between the control circuit terminal 1 and 12 volts. Install a jumper wire between the ground circuit terminal 3 and ground. Verify the release actuator activates.

⇒ | If the actuator does not perform as specified, replace the liftgate latch.

#### Liftgate Switch

1. Ignition OFF, disconnect the harness connector at the liftgate switch.
2. Test for infinite resistance between the signal terminal A and the ground circuit terminal C with the switch in the open position.

⇒ | If not the specified value, replace the liftgate switch.

3. Test for less than 2 ohms between the signal terminal A and the ground circuit terminal C with the switch in the closed position.

⇒ | If greater than the specified range, replace the liftgate switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Liftgate Outside Handle Replacement

• | Control Module References for BCM replacement, setup, and programming