GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2008 🢒 LaCrosse 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Trunk Release Inoperative

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 Release Control

1

1

1

--

Door Lock Switch Unlock Signal

2

2

2

--

Rear Compartment Lid Latch Ground

--

1

1

--

1. Trunk release is inoperative from both the switch and keyless entry transmitter

2. Trunk release is inoperative only from switch

Circuit/System Description

The rear compartment lid can be released by holding the left front power door lock switch to the unlock position for a minimum of 2 seconds or by pressing the rear compartment release button on the key fob. The transaxle must be in the PARK position for the rear compartment to release. When the rear compartment lid release is commanded, voltage is applied to the rear compartment lid release actuator from the BCM, thus opening the rear compartment.

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
  1. Ignition ON, command the doors to LOCK and UNLOCK by using the left front door lock switch.
    2. ⇒If the left front door lock switch is inoperative, refer to Power Door Locks Inoperative .
  2. Command the trunk release with a scan tool, the rear compartment lid latch should release the trunk lid.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the rear compartment lid latch.
  2. Test for less than 1 ohm between the ground circuit terminal 3 and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 4 and ground.
  4. Command the trunk release ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    5. ⇒If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    ⇒If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. 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. Install a 7.5-amp fused jumper wire between the control terminal 4 and 12 volts. Install a jumper wire between the ground terminal 3 and ground. Verify the rear compartment lid latch activates.
    3. ⇒If the latch does not perform as specified, replace the rear compartment lid latch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Rear Compartment Lid Latch Replacement
    •  Control Module References for BCM replacement, setup, and programming