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
--- | --- | --- | --- | ---
Trunk Ajar Switch Signal | 2 | 1 | 1 | --
Rear Compartment Lid Ajar Switch Ground | -- | 1 | 1 | --
1. Trunk Ajar Indicator Always Off 2. Trunk Ajar Indicator Always Illuminated

### Circuit/System Description

The body control module (BCM) receives a discrete input from the rear compartment lid ajar switch signal circuit. When the rear compartment is opened, the normally open rear compartment lid ajar switch closes. With the rear compartment lid ajar switch closed, ground is provided to the rear compartment lid ajar switch signal circuit. The BCM interprets this and sends a serial data message to the instrument panel cluster (IPC). When the rear compartment is open/ajar and the vehicle is in any gear other than PARK, the driver information center (DIC) will display TRUNK AJAR. If the rear compartment is still ajar and the vehicles speed is greater than 5 km/h (3 mph) a chime will sound.

### Reference Information

#### Schematic Reference

Release Systems Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Luggage Compartment 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 and the IPC TRUNK AJAR indicator while opening and closing the trunk. The parameter should change between Trunk Closed and Trunk Ajar and the TRUNK AJAR indicator should turn ON and OFF.

⇒ | If the parameter changes but the TRUNK AJAR indicator is always OFF or always ON, replace the IPC.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the rear compartment lid ajar 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 Trunk Ajar Switch parameter is Trunk Closed.

⇒ | 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. Install a 3A fused jumper wire between the signal circuit terminal A and ground. 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.

5. If all circuits tests normal, test or replace the rear compartment lid ajar switch.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the rear compartment lid latch.
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 rear compartment lid latch.

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 rear compartment lid latch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Rear Compartment Latch Striker Replacement

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