Liftgate Release Malfunction (Manual Liftgate)
Liftgate Release Malfunction (Manual Liftgate)
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 release switch is an input to the body control module (BCM). The BCM monitors the signal circuit and when the release switch is activated the signal circuit voltage goes low. The BCM controls the liftgate release actuator through the liftgate latch release relay. When the release switch signal is activated, the BCM enables the liftgate latch release relay by applying battery voltage to the liftgate latch release relay supply circuit and the relay is energized when the BCM grounds the liftgate latch release relay control circuit. When the relay is energized battery voltage is supplied to the liftgate release actuator through the liftgate release actuator 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 End Views By Name
Description and Operation
Liftgate Description and Operation Liftgate
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 observe the scan tool Liftgate Handle Sw. parameter while using the liftgate handle switch, the parameter should change from Inactive to Active.
• If the value does not change, refer to Liftgate Handle Switch Malfunction.
2. Command the liftgate to release by using the liftgate handle switch, the liftgate latch assembly should release the liftgate.
• If the liftgate latch assembly does not release the liftgate, refer to Liftgate Latch Malfunction.
Circuit/System Testing
Liftgate Release Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the liftgate handle switch.
2. Test for less than 1 ohms between the ground circuit terminal B and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Liftgate Handle Sw parameter is Inactive.
• If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the body control module.
4. Install a 3 A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Liftgate Handle Sw 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 body control module.
5. If all circuits test normal, test or replace the liftgate handle switch.
Liftgate Release Malfunction
1. Ignition OFF, disconnect the harness connector at the liftgate latch assembly.
2. Test for less than 5 ohms between the ground circuit terminal 3 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal 1 and ground.
4. Ignition ON, command the liftgate latch assembly to UNLATCH by pressing the liftgate handle switch. The test lamp should 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 fuse block-underhood.
• If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the liftgate latch assembly
• If the test lamp is always OFF and the circuit fuse is good, 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 liftgate latch assembly.
Underhood Panel Fuse Block Test
1. Ignition OFF, disconnect the X7 harness connector at the body control module.
2. Connect a 10 A fused jumper wire between the control circuit terminal 3 and B+, briefly connect a jumper wire between the control circuit terminal 1 and ground. Verify the liftgate latch is activated.
• If the liftgate latch does not activate, test either control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the fuse block-underhood.
3. If all circuits test normal, replace the body control module.
Component Testing
Liftgate Latch
1. Ignition OFF, disconnect the harness connector at the 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 liftgate latch assembly activates.
• If the liftgate latch assembly does not perform as specified, replace the liftgate latch assembly.
Liftgate Release Switch
1. Ignition OFF, disconnect the harness connector at the liftgate handle switch.
2. Test for infinite resistance between the signal terminal A and the ground terminal B with the switch in the open position.
• If not the specified value, replace the liftgate handle switch.
3. Test for less than 2 ohms between the signal terminal A and the ground terminal B with the switch in the closed position.
• If greater than the specified range, replace the liftgate handle switch.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Liftgate Latch Replacement Liftgate Latch Replacement
* Liftgate Release Switch Replacement (Except Avalanche and Escalade EXT) Liftgate Release Switch Replacement
* Underhood Electrical Center or Junction Block Replacement Underhood Electrical Center or Junction Block Replacement
* Control Module References Control Module References for BCM replacement, programming and setup