Liftgate Ajar Indicator Malfunction (TB4)
Liftgate Ajar Indicator Malfunction (TB4)
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 provide an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The body control module (BCM) supplies a 12 V signal to the liftgate ajar switch signal circuit. When the liftgate latch releases the liftgate, the liftgate ajar switch, which is internal to the liftgate latch, is supplied with ground which causes the rear hatch/gate ajar switch signal circuit to be pulled low. The BCM interprets this and communicates via serial data to the driver information center which will display the Liftgate Open message.
Diagnostic Aids
Before testing can be performed the liftgate must be opened. Refer to Opening the Liftgate Without Electrical Power Service and Repair for the procedure.
Reference Information
Schematic Reference
Release Systems Schematics Release Systems Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left Front
Description and Operation
Liftgate Ajar Indicator Description and Operation Liftgate Ajar Indicator
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 Rear Closure Ajar Switch parameter changes between Inactive and Active when opening and closing the liftgate.
• If the parameter does not change
Refer to Circuit/System Testing.
• If the parameter changes
3. All OK.
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the A23C liftgate latch assembly. 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 5 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 Rear Closure Ajar 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 6 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 6 and the ground circuit terminal 5.
6. Verify the scan tool Rear Closure Ajar 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 A23C liftgate latch assembly.
Component Testing
1. Ignition OFF, disconnect the harness connector at the A23C liftgate latch assembly.
2. Test for infinite resistance between the signal terminal 6 and the ground terminal 5 with the switch in the open position.
• If less than infinite resistance
Replace the A23C liftgate latch assembly.
• If infinite resistance
3. Test for less than 3 ohms between the signal terminal 6 and the ground terminal 5 with the switch in the closed position.
• If 3 ohms or greater
Replace the A23C liftgate latch assembly.
• If less than 3 ohms
4. All OK
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Liftgate Latch Replacement Service and Repair
* Control Module References Control Module References for BCM replacement, setup, and programming