Trunk Release Malfunction
Trunk Release Malfunction (Sedan)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) 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 lock/window switch. When the interior rear compartment lid release switch is activated, the signal circuit is pulled to ground. The driver door lock/window switch interprets this and sends a 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/RELSE 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 exterior rear compartment lid release switch receives a signal from the remote control door lock receiver. When the exterior rear compartment lid release switch is activated, the signal circuit is pulled to ground. The remote control door lock receiver interprets this and sends a serial data message to the 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/RELSE 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.
Reference Information
Schematic Reference
Release Systems Schematics (Release Systems Schematics)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Luggage Compartment Description and Operation (Luggage Compartment)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, command the Trunk Release with a scan tool. The M40 rear compartment lid latch should release the trunk lid.
• If the M40 rear compartment lid latch is inoperative, refer to Rear Compartment Lid Malfunction.
2. Observe the scan tool LGM Front Control Switch parameter while pressing the S58B rear compartment lid release switch - interior. The value should change from Inactive to Active each time the switch is pressed.
• If the value does not change, refer to Interior Trunk Release Switch Malfunction.
3. Observe the scan tool Remote Control Door Lock Receiver Trunk Release Switch parameter while pressing the S58A rear compartment lid unlatch switch-exterior. The value should change from Inactive to Active each time the switch is pressed.
• If the value does not change, refer to Exterior Trunk Release Switch Malfunction.
Circuit/System Testing
Rear Compartment Lid Release Malfunction
1. Ignition OFF, disconnect the TRUNK/RELSE relay.
2. Test for less than 5 ohm between the ground circuit terminal 86 and ground.
• If greater than the specified range, test 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 B+ circuit terminal 87 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the TRUNK/RELSE fuse is open, test the control circuit terminal 30 for a short to ground.
5. Ignition OFF, disconnect the harness connector at the M40 rear compartment lid latch.
6. Test for less than 5 ohm 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 M40 rear compartment lid latch.
8. Ignition ON, connect a 15 A fused jumper wire between the B+ circuit terminal 87 and the control circuit terminal 30. Verify the M40 rear compartment lid latch is activated.
• If the M40 rear compartment lid latch does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the M40 rear compartment lid latch.
9. Connect a test lamp between the control circuit terminal 85 and ground.
10. Command the Trunk Release with a scan tool. The test lamp should illuminate during the RELEASE command.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 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 K9 BCM.
11. If all circuits test normal, test or replace the TRUNK/RELSE relay.
Interior Trunk Release Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the S58B rear compartment lid release switch - interior.
2. Test for less than 5 ohm between the low reference circuit terminal A and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance, if the circuit tests normal, replace the S84D door lock/window switch-driver.
3. Ignition ON, verify the scan tool LGM Front Control Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the S84D door lock/window switch-driver.
4. Install a 3 A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool LGM Front Control 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 S84D door lock/window switch-driver.
5. If all circuits test normal, test or replace the S58B rear compartment lid release switch - interior.
Exterior Trunk Release Switch Malfunction
1. Ignition OFF, disconnect the X900 inline harness connector at the S58A rear compartment lid unlatch switch-exterior.
2. Ignition ON, test for less than 30 ohm between the ground circuit terminal 7 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Verify the scan tool Remote Control Door Lock Receiver Trunk Release Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the K77 remote control door lock receiver.
4. Install a 3 A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Remote Control Door Lock Receiver 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 K77 remote control door lock receiver.
5. If all circuits test normal, test or replace the S58A rear compartment lid unlatch switch-exterior.
Component Testing
Rear Compartment Lid Latch
1. Ignition OFF, disconnect the harness connector at the M40 rear compartment lid latch.
2. Install a 15 A fused jumper wire between the control terminal A and 12 V. Briefly install a jumper wire between the ground terminal B and ground. Verify the M40 rear compartment lid latch activates.
• If the M40 rear compartment lid latch does not perform as specified, replace the M40 rear compartment lid latch.
Interior Rear Compartment Lid Unlatch Switch Test
1. Ignition OFF, disconnect the harness connector at the S58B rear compartment lid release switch - interior.
2. Test for infinite resistance between the signal terminal C and the low reference terminal A with the switch in the open position.
• If not the specified value, replace the S58B rear compartment lid release switch - interior.
3. Test for less than 2 ohm between the signal terminal C and the low reference terminal A with the switch in the closed position.
• If greater than the specified range, replace the S58B rear compartment lid release switch - interior.
Exterior Rear Compartment Lid Unlatch Switch Test
1. Ignition OFF, disconnect the X900 inline harness connector at the S58A rear compartment lid unlatch switch-exterior.
2. Test for infinite resistance between the signal circuit terminal 2 and the ground circuit terminal 7 with the switch in the open position.
• If not the specified value, replace the S58A rear compartment lid unlatch switch-exterior.
3. Test for less than 5 ohm between the signal circuit terminal 2 and the ground circuit terminal 7 with the switch in the closed position.
• If greater than the specified range, replace the S58A rear compartment lid unlatch switch-exterior.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Rear Compartment Lid Release Switch Replacement (Sedan and Coupe) (Service and Repair)
* Rear Compartment Lid Latch Replacement (Coupe) (Rear Compartment Lid Latch Replacement)Rear Compartment Lid Latch Replacement (Sedan) (Rear Compartment Lid Latch Replacement)
* Liftgate Outside Handle Replacement (Sedan and Coupe) (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, driver door lock/window switch, or remote control door lock receiver replacement, setup, and programming