Liftgate Release Malfunction (Manual)
Liftgate Release Malfunction (Manual)
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 liftgate switch is an input to the body control module (BCM). The BCM supplies 12 volts to the signal circuit and when the liftgate switch is activated the signal circuit voltage goes low. The BCM controls the liftgate latch assembly through the liftgate release PCB relay. When the liftgate switch signal is activated, the BCM enables the liftgate release relay by applying battery voltage to the relay circuit high and the relay is energized when the BCM grounds the relay control circuit low. When the relay is energized battery voltage is supplied to the liftgate latch assembly through the liftgate latch control circuit.
Diagnostic Aids
Before testing can be performed, the liftgate must be opened. Refer to Opening the Liftgate Without Electrical Power (Procedures) for the appropriate procedure.
Reference Information
Schematic Reference
Release Systems Schematics (Release Systems Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Rear Hatch/Gate Description and Operation (Rear Hatch/Gate Description and Operation)
Electrical Information Reference
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Circuit Testing (Circuit Testing)
* Wiring Repairs (Wiring Repairs)
* Connector Repairs (Connector Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool Trunk Lid/Liftglass Exterior Unlatch Switch parameter while pressing and releasing the S46 liftgate handle switch. The reading should change between Active and Inactive.
• If the value does not change, refer to Liftgate Handle Switch Malfunction.
2. Command the M31 liftgate latch assembly to UNLATCH with a scan tool. The M31 liftgate latch assembly should release the liftgate.
• If the M31 liftgate latch assembly does not perform as specified, refer to Liftgate Release Malfunction.
Circuit/System Testing
Liftgate Handle Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the S46 liftgate handle switch.
2. 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.
3. Ignition ON, verify the scan tool Trunk Lid/Liftglass Exterior 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 Trunk Lid/Liftglass Exterior 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 S46 liftgate handle switch.
Liftgate Release Malfunction
1. Ignition OFF, disconnect the harness connector at the A23C liftgate latch assembly.
2. Test for less than 30 ohm between the ground circuit terminal 3 and ground.
• If greater than the specified range, test the ground circuit for and open/high resistance.
3. Connect a test lamp between the control circuit terminal 1 and the ground circuit terminal 3.
4. Ignition ON, command the A23C liftgate latch assembly to UNLATCH with a scan tool. The test lamp should briefly illuminate 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 X50A fuse block-underhood.
• If the test lamp is always OFF and the B+ circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the A23C liftgate latch assembly.
• If the test lamp is always OFF and the B+ circuit fuse is normal, test the control circuit for an open/high resistance. If the circuit tests normal, refer to Underhood Fuse Block Test.
5. If all circuits test normal, test or replace the A23C liftgate latch assembly.
Underhood Fuse Block Test
1. Ignition OFF, disconnect the X4 and X5 harness connectors at the K9 BCM.
2. Ignition ON, test for less than 1 V between each control circuit terminal listed below and ground:
* Low control circuit terminal 20 X5
* High control circuit terminal 8 X4
• If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the X50D fuse block-underhood.
3. Ignition OFF, test for infinite resistance between each control circuit terminal listed below and ground:
* Low control circuit terminal 20 X5
* High control circuit terminal 8 X4
• If not the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the X50D fuse block-underhood.
4. Ignition ON, connect a 10 A fused jumper wire between the high control circuit terminal 8 X4 and B+ and a jumper wire between the low control circuit terminal 20 X5 and ground. Verify the A23C liftgate latch assembly is activated.
• If the A23C liftgate latch assembly does not activate, test each control circuit for an open/high resistance. If the circuit tests normal, replace the X50A fuse block-underhood.
5. If all circuits test normal, replace the K9 BCM.
Component Testing
Liftgate Latch Assembly
1. Ignition OFF, disconnect the harness connector at the A23C liftgate latch assembly.
2. Install a 15 A fused jumper wire between the control terminal 1 and 12 V. Install a jumper wire between the ground terminal 3 and ground. Verify the release actuator activates.
• If the actuator does not perform as specified, replace the A23C liftgate latch assembly.
Liftgate Release Switch
1. Ignition OFF, disconnect the harness connector at the S46 liftgate handle switch.
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 S46 liftgate handle switch.
3. Test for less than 2 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 S46 liftgate handle switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.
* Liftgate Release Switch Replacement (Liftgate Release Switch Replacement)
* Liftgate Latch Replacement (Service and Repair)
* Accessory Wiring Junction Block Replacement (Accessory Wiring Junction Block Replacement)
* Control Module References (Programming and Relearning) for BCM replacement, setup and programming