Liftgate Ajar Indicator Malfunction

Liftgate Ajar Indicator Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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/System Description

The liftgate can be released by operating the liftgate release switch or by pressing the liftgate release button on the remote keyless entry transmitter. The gear selector may be in any position, but the vehicle speed must equal 0 for the liftgate to release.

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

Circuit/System Verification

With the ignition key ON, the liftgate ajar indicator should illuminate when the liftgate is opened and go off when the liftgate is closed.

Circuit/System Testing

1. Ignition OFF, disconnect the C1 harness connector of the liftgate door latch.
2. Ignition OFF, test for less than 1 ohm of resistance between the ajar switch ground circuit and ground.

• If greater than 1 ohm, test the ground circuit for an open/high resistance.

3. Using a scan tool, verify the Trunk Ajar Switch parameter is Closed.

• If not Closed, test that signal circuit for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3-amp fused jumper wire between the signal circuit and ground. Verify the Trunk Ajar Switch parameter is Ajar.

• If not Ajar, test the signal circuit of the liftgate ajar switch 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 ajar switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* Liftgate Latch Replacement
* Control Module References for BCM replacement, setup, and programming. Verification Tests