Trunk Release Malfunction
Trunk Release Malfunction
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 Body Control Module (BCM) supplies a 12 V reference voltage to the rear compartment lid unlatch switch through the release switch signal circuit. When the rear compartment lid unlatch switch is pressed, the release switch signal circuit is grounded through the rear compartment lid unlatch switch ground circuit and the reference voltage is pulled low within the BCM. In response, the BCM applies battery positive voltage to the rear compartment lid release relay control circuit, which energizes the coil side of the relay. The switch side of the rear compartment lid release relay then closes, supplying battery positive voltage through the relay and the Rear Compartment Lid Latch control circuit activating the latch so that the trunk lid may be manually raised to an open position.
Reference Information
Schematic Reference
Release Systems Schematics Release Systems Schematics
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Luggage Compartment Description and Operation Description and Operation
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 Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify the scan tool Trunk Lid/Liftgate Window Exterior Unlatch Switch parameter changes between Active and Inactive when pressing and releasing the S58A Rear Compartment Lid Unlatch Switch-Exterior.
• If the parameter does not change
Refer to Circuit/System Testing - Exterior Trunk Release Switch Inoperative
• If the parameter changes
3. Verify the scan tool Interior Liftgate/Liftgate Window Unlatch Switch parameter changes between Active and Inactive when pressing and releasing the S58B Rear Compartment Lid Unlatch Switch-Interior.
• If the parameter does not change
Refer to Circuit/System Testing - Interior Trunk Release Switch Inoperative
• If the parameter changes
4. Verify the operation of the M40 Rear Compartment Lid Latch when commanding the Trunk Lid Unlatch with a scan tool.
• If the M40 Rear Compartment Lid Latch does not Unlatch
Refer to Circuit/System Testing - Release Actuator Inoperative
• If the M40 Rear Compartment Lid Latch does Unlatch
5. All OK.
Circuit/System Testing
Exterior Trunk Release Switch Inoperative
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S58A Rear Compartment Lid Unlatch Switch-Exterior. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 2 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Ignition ON.
4. Verify the scan tool Trunk Lid/Liftgate Window Exterior Unlatch Switch parameter is Inactive.
• If not Inactive
1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
2. Test for infinite resistance between the signal circuit terminal 1 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K9 Body Control Module.
• If Inactive
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the ground circuit terminal 2.
6. Verify the scan tool Trunk Lid/Liftgate Window Exterior Unlatch Switch parameter is Active.
• If not Active
1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 Body Control Module.
• If Active
7. Test or replace the S58A Rear Compartment Lid Unlatch Switch-Exterior.
Interior Trunk Release Switch Inoperative
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S58B Rear Compartment Lid Unlatch Switch-Interior. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 2 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Ignition ON.
4. Verify the scan tool Interior Liftgate/Liftgate Window Unlatch Switch parameter is Inactive.
• If not Inactive
1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
2. Test for infinite resistance between the signal circuit terminal 1 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K9 Body Control Module.
• If Inactive
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the ground circuit terminal 2.
6. Verify the scan tool Interior Liftgate/Liftgate Window Unlatch Switch parameter is Active.
• If not Active
1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 Body Control Module.
• If Active
7. Test or replace the S58B Rear Compartment Lid Unlatch Switch-Interior.
Release Actuator Inoperative
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the M40 Rear Compartment Lid Latch. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 2 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Ignition ON, connect a test lamp between the control circuit terminal 1 and the ground circuit terminal 2.
4. Verify the test lamp briefly turns ON when commanding the Trunk Lid Unlatch with a scan tool.
• If the test lamp is always ON
1. Ignition OFF, disconnect the harness connector at the X50A Fuse Block-Underhood, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the X50A Fuse Block-Underhood.
• If the test lamp is always OFF and the circuit fuse is open
1. Ignition OFF, disconnect the harness connector at the X50A Fuse Block-Underhood.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If the test lamp is always OFF and the circuit fuse is good
1. Ignition OFF, disconnect the harness connector at the X50A Fuse Block-Underhood.
2. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, refer to Underhood Fuse Block Test.
• If the test lamp turns ON and OFF
5. Test or replace the M40 Rear Compartment Lid Latch.
Underhood Fuse Block Test
1. Ignition OFF and all vehicle systems OFF, disconnect the X1 harness connector at the X50A Fuse Block-Underhood. It may take up to 2 minutes for all vehicle systems to power down
2. Test for less than 10 ohms between the ground circuit terminal 71 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Connect the X1 harness connector at the X50A Fuse Block-Underhood and disconnect the X5 harness connector at the K9 Body Control Module.
4. Verify that a test lamp does not illuminate between the control circuit terminal 11 and ground.
• If the test lamp illuminates
Repair the short to voltage on the control circuit
• If the test lamp does not illuminate
5. Briefly connect a 3A fused jumper wire between the control circuit terminal 11 and B+, verify the M40 Rear Compartment Lid Latch activates.
• If the M40 Rear Compartment Lid Latch does not activate
1. Ignition OFF, disconnect the X2 harness connector at the X50A Fuse Block-Underhood, ignition ON.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the X50A Fuse Block-Underhood.
3. Ignition OFF.
4. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the X50A Fuse Block-Underhood.
• If the M40 Rear Compartment Lid Latch activates
6. Replace the K9 Body control Module.
Component Testing
Rear Compartment Lid Latch
1. Ignition OFF, disconnect the harness connector at the M40 Rear Compartment Lid Latch.
2. Install a 10 A fused jumper wire between the control terminal 1 and 12 V. Install a jumper wire between the ground terminal 2 and ground.
3. Verify the M40 Rear Compartment Lid Latch activates
• If the M40 Rear Compartment Lid Latch does not activate.
Replace the M40 Rear Compartment Lid Latch.
• If the M40 Rear Compartment Lid Latch does activate.
4. All OK
Exterior Trunk Release Switch
1. Ignition OFF, disconnect the harness connector at the S58A Rear Compartment Lid Unlatch Switch-Exterior.
2. Test for infinite resistance between the signal terminal 1 and the ground terminal 2 with the switch in the open position.
• If less than infinite resistance
Replace the S58A Rear Compartment Lid Unlatch Switch-Exterior.
• If infinite resistance
3. Test for less than 3 ohms between the signal terminal 1 and the ground terminal 2 with the switch in the closed position.
• If 3 ohms or greater
Replace the S58A Rear Compartment Lid Unlatch Switch-Exterior.
• If less than 3 ohms
4. All OK
Interior Trunk Release Switch
1. Ignition OFF, disconnect the harness connector at the S58B Rear Compartment Lid Unlatch Switch-Interior.
2. Test for infinite resistance between the signal terminal 1 and the ground terminal 2 with the switch in the open position.
• If less than infinite resistance
Replace the S58B Rear Compartment Lid Unlatch Switch-Interior.
• If infinite resistance
3. Test for less than 3 ohms between the signal terminal 1 and the ground terminal 2 with the switch in the closed position.
• If 3 ohms or greater
Replace the S58B Rear Compartment Lid Unlatch Switch-Interior.
• If less than 3 ohms
4. All OK
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Front Compartment Fuse Block Replacement Front Compartment Fuse Block Replacement
* Rear Compartment Lid Release Switch Replacement Service and Repair
* Rear Compartment Lid Latch Replacement Service and Repair
* Control Module References Control Module References for BCM replacement, programming and setup