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 provide an overview of each diagnostic category.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Rear Compartment Lid Ajar Switch Signal | 1 | 2 | 2 | --
Rear Compartment Lid Latch Ground | -- | 3 | 3 | --
1. Trunk Ajar Indicator Always Illuminated. 2. Trunk Ajar Indicator Inoperative. 3. Trunk Release Inoperative.

### Circuit/System Description

The rear compartment lid can be released by operating the rear compartment lid release switch or by pressing the rear compartment release button on the remote keyless entry transmitter. The gear selector may be in any position, but the vehicle must be stationary for the rear compartment lid to release.

When the ignition is ON, the body control module (BCM) supplies battery positive voltage to the rear compartment lid ajar switch through the rear compartment lid ajar switch signal circuit. When the rear compartment lid is opened, the signal circuit is connected to ground through the rear compartment lid ajar switch ground circuit and the voltage is pulled low within the BCM. In response, the BCM sends a serial data message to the driver information center (DIC) in the instrument panel cluster (IPC) to illuminate the rear compartment lid ajar indicator.

### Reference Information

#### Schematic Reference

Release Systems Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Door Ajar Indicator Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Ignition ON, observe the scan tool Trunk Ajar Switch parameter while opening and closing the rear compartment lid, the parameter should change between Trunk Closed and Trunk Ajar.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the rear compartment lid release actuator.
2. Ignition ON, verify the scan tool Trunk Ajar Switch parameter is Trunk Closed.

⇒ | If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the BCM.

3. Install a 3A fused jumper wire between the signal circuit terminal 2 and the ground circuit terminal 3. Verify the scan tool Trunk Ajar Switch parameter is Trunk Ajar.

⇒ | 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.

4. If all circuits test normal, test or replace the rear compartment lid release actuator.

### Component Testing

#### Rear Compartment Lid Release Actuator

1. Ignition OFF, disconnect the harness connector at the rear compartment lid release actuator.
2. Test for infinite resistance between the signal terminal 2 and the ground terminal 3 with the switch in the open position.

⇒ | If not the specified value, replace the rear compartment lid release actuator.

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

⇒ | If greater than the specified range, replace the rear compartment lid release actuator.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Rear Compartment Lid Latch Replacement

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