GM Service Manual Online
For 1990-2009 cars only

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

Rear Compartment Lid Ajar Switch Signal

1

2

2

--

Rear Compartment Lid Latch Ground

--

3

3

--

1. Trunk Ajar Message Aways Illuminated

2. Trunk Ajar Message Inoperative

3. Trunk Release Inoperative

Circuit/System Description

The body control module (BCM) uses the rear compartment lid latch to determine the position of the trunk lid. When the lid is open, the rear compartment lid ajar switch is closed, providing a ground path for the trunk ajar switch signal circuit. When the BCM detects the trunk lid is ajar, a serial data message is sent to the driver information center (DIC) requesting the Trunk Ajar message be displayed.

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 Open Switch parameter while opening and closing the trunk lid. The parameter should change between Open and Closed.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the rear compartment lid latch.
  2. Ignition ON, verify the scan tool Trunk Open Switch parameter is Closed.
  3. If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the BCM.
    If the scan tool parameter is Closed and the DIC message displays Trunk Ajar, replace the DIC.
  4. Install a 3-amp fused jumper between the signal circuit terminal 2 and ground. Verify the scan tool Trunk Open Switch parameter is Open.
  5. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
    If the scan tool parameter is Open and the DIC message is not displayed, replace the DIC.
  6. If all circuits test normal, test or replace the rear compartment lid latch.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the rear compartment lid latch.
  2. Test for infinite resistance between the signal terminal 2 and the ground terminal 3 in the open position.
  3. If not the specified value, replace the rear compartment lid latch.
  4. Test for less than 2.0 ohms between the signal terminal 2 and the ground terminal 3 in the closed position.
  5. 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 Lid Ajar Indicator Switch Replacement
    •  Control Module References for BCM and DIC replacement, setup and programming