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 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 compartment lid release relay control circuit, which energizes the coil side of the relay. The switch side of the 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 (Connector End Views By Name)
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 (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool Interior Trunk Lid/Liftgate Window Unlatch Switch parameter while pressing and releasing the S58 rear compartment lid unlatch switch. The parameter should be Inactive and change to Active when the switch is pressed.
• If the value does not change, refer to Trunk Release Switch Inoperative.
2. Command the M40 rear compartment lid latch to UNLATCH with a scan tool. The M40 rear compartment lid latch should release the deck lid.
• If the M40 rear compartment lid latch does not release the deck lid, refer to Release Actuator Inoperative.
Circuit/System Testing
Trunk Release Switch Inoperative
1. Ignition OFF, disconnect the harness connector at the S58A rear compartment lid unlatch switch-exterior.
2. Ignition ON, test for less than 10 ohm between the ground circuit terminal 2 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Verify the scan tool Interior Trunk Lid/Liftgate Window Unlatch Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K9 BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Interior Trunk Lid/Liftgate Window Unlatch 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 K9 BCM.
5. If all circuits test normal, test or replace the S58A rear compartment lid unlatch switch-exterior.
Release Actuator Inoperative
1. Ignition OFF for 10 minutes, disconnect the KR95B rear compartment lid release relay.
2. Test for less than 10 ohm between the ground circuit terminal 1 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 5 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 4 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 B+ circuit fuse is open, test the control circuit terminal 5 for a short to ground. If the circuit tests normal, test or replace the KR95B rear compartment lid release relay.
5. Ignition OFF, disconnect the harness connector at the M40 rear compartment lid latch.
6. Test for less than 30 ohm between the ground circuit terminal 2 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 10 A fused jumper wire between the B+ circuit terminal 4 and the control circuit terminal 5. 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 3 and the ground circuit terminal 1.
10. Command the M40 rear compartment lid latch to UNLATCH with a scan tool. The test lamp should turn ON during the UNLATCH 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 KR95B rear compartment lid release relay.
Component Testing
Rear Compartment Lid Latch Test
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 1 and B+. Momentarily Install a jumper wire between the ground terminal 2 and ground. Verify the M40 rear compartment lid latch.
• If the actuator does not perform as specified, replace the M40 rear compartment lid latch.
Rear Compartment Lid Unlatch Switch Test
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 not the specified value, replace the S58A Rear Compartment Lid Unlatch Switch - Exterior.
3. Test for less than 5 ohm between the signal terminal 1 and the ground terminal 2 with the switch in the closed position.
• If greater than the specified range, replace the S58A Rear Compartment Lid Unlatch Switch - Exterior.
Relay Test
1. Ignition OFF, disconnect the KR95B rear compartment lid release relay.
2. Test for 60-180 ohm between terminals 1 and 2.
• If not within the specified range, replace the KR95B rear compartment lid release relay.
3. Test for infinite resistance between the following terminals:
* 3 and 2
* 3 and 5
* 3 and 1
* 1 and 5
• If not the specified value, replace the KR95B rear compartment lid release relay.
4. Install a 5A fused jumper wire between relay terminal 2 and 12V. Install a jumper wire between relay terminal 1 and ground. Test for less than 2 ohm between terminals 3 and 5.
• If greater than the specified range, replace the KR95B rear compartment lid release relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Rear Compartment Lid Release Switch 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))
* Rear Compartment Lid Latch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming