Trunk Release Inoperative
Trunk Release Inoperative
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The interior rear compartment lid release switch receives a signal from the driver door module (DDM). When the interior rear compartment lid release switch is activated, the signal circuit is pulled to ground. The DDM interprets this and sends a GMLAN serial data message to the body control module (BCM) requesting the rear compartment lid be released. The BCM responds by applying battery voltage to the trunk release relay control circuit which energizes the TRUNK RELES relay. The trunk release relay is supplied with battery voltage at all times. With the relay coil energized, the relay switch contacts close allowing battery voltage to flow to the rear compartment lid release actuator causing the rear compartment lid to release. The rear compartment lid release actuator is permanently grounded at G401. When the rear compartment lid release actuator releases the rear compartment lid, the rear compartment lid ajar switch, which is internal the rear compartment lid release actuator, is supplied with ground which causes the trunk ajar switch signal circuit to be pulled low. The trunk ajar switch signal circuit is an input to the BCM. When the BCM receives a trunk ajar signal, a GMLAN serial data message is sent to the instrument panel cluster (IPC) requesting the TRUNK OPEN message be displayed on the message center.
Reference Information
Schematic Reference
* Release Systems Schematics (Release Systems Schematics)
* Remote Function Schematics (Remote Function Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Luggage Compartment Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool trunk release switch parameter located in the driver door switch menu while activating the interior rear compartment lid release switch ON and OFF. The reading should toggle between ACTIVE and INACTIVE.
If the readings do not change as the switch is activated, refer to Trunk Release Switch Malfunction.
Circuit/System Testing
Trunk Release Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the interior rear compartment lid release switch.
2. Ignition OFF, scan tool OFF, test for less than 10.0 ohms between the ground circuit terminal A and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the DDM.
3. Ignition ON, verify the scan tool trunk release switch parameter located in the driver door switch menu is INACTIVE.
• If not the specified value, test the signal circuit terminal C for a short to ground. If the circuit tests normal, replace the DDM.
4. Install a 3A fused jumper wire between the signal circuit terminal C and ground. Verify the scan tool trunk release switch parameter is ACTIVE.
• 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 DDM.
5. If all circuits test normal, test or replace the interior rear compartment lid release switch.
Trunk Release Malfunction
1. Ignition OFF, disconnect the trunk release relay.
2. Ignition OFF, test for less than 5.0 ohms between the relay coil ground circuit terminal 85 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 30 and ground.
• If the test lamp illuminates, test the control circuit for a short to voltage.
4. Verify that a test lamp illuminates between the relay switch B+ circuit terminal 87 and ground.
• If the test lamp does not illuminate, test the relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test the relay controlled output circuit terminal 30 for a short to ground.
5. Ignition OFF, disconnect the harness connector at the rear compartment lid latch.
6. Ignition OFF, test for less than 5.0 ohms between the ground circuit terminal B and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the rear compartment lid latch.
8. Ignition ON, connect a 15A fused jumper wire between the B+ circuit terminal 87 and the control circuit terminal 30. Verify the rear compartment lid release actuator is activated.
• If the rear compartment lid release actuator does not activate, test the control circuit terminal 30 for an open/high resistance. If the circuit tests normal, test or replace the rear compartment lid latch.
9. Ignition OFF, connect a test lamp between the relay control circuit terminal 86 and the relay coil ground circuit terminal 85.
10. Command the trunk release relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
• 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.
11. If all circuits test normal, test or replace the trunk release relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Rear Compartment Lid Switch Replacement (Service and Repair)
* Rear Compartment Lid Latch Replacement (Service and Repair)
* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Control Module References (Programming and Relearning) for BCM or DDM replacement, setup, and programming