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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 voltage 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 relay. When the liftgate switch signal is activated, the BCM enables the liftgate release relay by applying battery voltage to the liftgate relay circuit and the relay is energized when the BCM grounds the liftgate release relay control circuit. 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

Liftgate Schematics (Liftgate Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Rear Hatch/Gate Description and Operation (Rear Hatch/Gate)
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 the S46B liftgate release switch. The reading should change between Active and Inactive.

• If the parameter does not change, refer to Liftgate Release Switch Malfunction.

2. Command the endgate to UNLATCH with a scan tool. The M31 liftgate latch assembly should release the liftgate.

• If the M31 liftgate latch assembly does not release the liftgate, refer to Liftgate Latch Malfunction (Except UA2/UTC).
• If the M31 liftgate latch assembly does not release the liftgate, refer to Liftgate Latch Malfunction (With UA2/UTC).

Circuit/System Testing

Liftgate Release Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the S46B liftgate release switch.
2. Test for less than 5 ohm between the ground circuit terminal 1 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 parameter, test the signal circuit terminal 2 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 2 and ground. Verify the scan tool Trunk Lid/Liftglass Exterior Unlatch Switch parameter is Active.

• If not the specified parameter, 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 S46B liftgate release switch.

Liftgate Latch Malfunction (Except UA2/UTC)
1. Ignition OFF, disconnect the RR CLOSURE relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 30 and ground.

• If the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the B+ circuit terminal 87 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 30 for a short to ground. If the circuit tests normal, test or replace the RR CLOSURE relay.

4. Connect a test lamp between the control circuit terminal 86 and B+.
5. Command the endgate 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 ground. If the circuit tests normal, replace the K9 BCM.
• If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.

6. Connect a test lamp between the control circuit terminal 85 and ground.
7. Command the endgate 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 B+. 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

8. Ignition OFF, disconnect the X1 harness connector at the M31 liftgate latch assembly.
9. Test for less than 5 ohm between the ground circuit terminal 3 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

10. Connect the X1 harness connector at the M31 liftgate latch assembly.
11. Connect a 15A fused jumper wire between the B+ circuit terminal 87 and the control circuit terminal 30. Verify the M31 liftgate latch assembly is activated.

• If the M31 liftgate latch assembly does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the M31 liftgate latch assembly.

12. If all circuits test normal, test or replace the RR CLOSURE relay.

Liftgate Latch Malfunction (With UA2/UTC)
1. Ignition OFF, disconnect the RR CLOSURE relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 30 and ground.

• If the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the B+ circuit terminal 87 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 30 for a short to ground. If the circuit tests normal, test or replace the RR CLOSURE relay.

4. Connect a test lamp between the control circuit terminal 86 and B+.
5. Command the endgate 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 ground. If the circuit tests normal, replace the K9 BCM.
• If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.

6. Connect a test lamp between the control circuit terminal 85 and ground.
7. Command the endgate 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 B+. 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

8. Ignition OFF, disconnect the RR CLOSURE 2 relay.
9. Test for less than 5 ohm between the ground circuit terminal 86 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

Component Testing

Liftgate Latch Assembly
1. Ignition OFF, disconnect the X1 harness connector at the M31 liftgate latch assembly.
2. Install a 15 A fused jumper wire between the control terminal 1 and 12 V. Momentarily install a jumper wire between the ground terminal 3 and ground. Verify the M31 liftgate latch assembly activates.

• If the actuator does not perform as specified, replace the M31 liftgate latch assembly.

Liftgate Release Switch
1. Ignition OFF, disconnect the harness connector at the S46B liftgate release switch.
2. Test for infinite resistance between the signal terminal 2 and the ground terminal 1 with the switch in the open position.

• If not the specified value, replace the S46B liftgate release switch.

3. Test for less than 2 ohm between the signal terminal 2 and the ground terminal 1 with the switch in the closed position.

• If greater than the specified range, replace the S46B liftgate release switch.

Relay Test
1. Ignition OFF, disconnect the appropriate K609 Rear Closure relay.
2. Test for 60-180 ohms between terminals 85 and 86.

• If not within the specified range, replace the K609 Rear Closure relay.

3. Test for infinite resistance between the following terminals:

* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87

• If not the specified value, replace the K609 Rear Closure relay.

4. Install a 25A fused jumper wire between relay terminal 85 and 12V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.

• If greater than the specified range, replace the K609 Rear Closure relay

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)
* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Control Module References (Programming and Relearning) for BCM replacement, setup and programming

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