Liftgate Release Malfunction (Power)
Liftgate Release Malfunction (Power)
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 control module controls operation of the liftgate latch motor and the liftgate actuator assembly. Under normal conditions the power latch can only be unlatched under power from the liftgate control module through an input from the liftgate handle switch, the open/close switch on the overhead console, or the remote keyless entry transmitter, but the liftgate may be manually closed to the primary latched position without the liftgate control module performing the power latch function. The liftgate mode switch in the driver door will enable or disable the power operation of the liftgate but will have no effect on power latch operation. The liftgate pump motor is a bi-directional motor and open or close operation is the result of the direction of the motor rotation. The liftgate module controls the liftgate pump motor through the control circuits by supplying power and ground in the appropriate polarity. The motor control circuits are monitored by the liftgate module prior to activation for a high or low condition and during motor operation for any irregular current flow conditions.
The liftgate control module continuously monitors power liftgate operation and calculates its location and direction of travel using 2 inputs from the liftgate position sensor. One input returns the position of the liftgate relative to the latch along the x-axis and the other returns the position of the liftgate relative to the latch along the y-axis. The liftgate control module then uses these 2 inputs together to calculate its angle relative to the liftgate latch.
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.
Power liftgate function will only be allowed if certain operating criteria are met. Any of the following may cause the power liftgate not to function:
* After a power loss of the low current battery supply until the ignition is cycled
* Vehicle is not in park
* Engine cranking is present.
* Ambient temperature at the liftgate control module must be within -17 to +80°C (+1 to +176°F).
* Liftgate motor excess current is detected which may be caused by a misaligned liftgate striker.
* System voltage is out of range.
* A DTC is set that disables power liftgate functionality.
* The vehicle doors are locked when attempting to open from the exterior handle.
* Interior trim and/or liftgate wedge/bumper misalignment.
A power liftgate that will not fully open may be caused by kinked or twisted hydraulic lines, inspect and replace any hydraulic lines.
Inspect the system for contaminated hydraulic fluid, improper fluid level and any hydraulic fluid leaks prior to any extensive electrical diagnostics; refer to Liftgate Hydraulic System Refilling (Liftgate Hydraulic System Refilling)
The liftgate module also receives input from 2 pressure sensing object detection sensors. If either of these sensors indicates an object may be pinched as the liftgate is brought to the closed position, the liftgate will reverse direction and power close operation will be suspended until the pressure against the sensor is released.
Whenever the liftgate module loses power or is disconnected, the ignition must be cycled OFF then ON in order to reactivate the liftgate module.
Certain SIR DTCs will make the power liftgate inoperative. Correct any SIR concern first before performing any extensive power liftgate diagnostics.
Reference Information
Schematic Reference
Liftgate Schematics (Liftgate Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Liftgate Description and Operation (Liftgate 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 Liftgate Front Control Switch parameter while pressing the open/close switch on the S58B Rear Compartment Lid Unlatch Switch - Interior. The parameter should change between Inactive and Active.
• If the values do not change, refer to Interior Liftgate Control Switch Malfunction
2. Observe the scan tool Liftgate Mode Switch parameters while selecting the mode switch between the 3/4 and Off settings. The values should be between 80 counts and 430 counts.
• If not within the specified range, refer to Interior Liftgate Control Switch Malfunction.
3. Observe the scan tool Liftgate Handle Switch parameter while pressing and releasing the S46 liftgate handle switch. The parameter should change between Active and Inactive.
• If the values do not change, refer to Liftgate Handle Switch Inoperative.
4. With the liftgate mode switch in the 3/4 or Max position, command the liftgate to power OPEN by pressing S46 liftgate handle switch. The liftgate latch should release and the liftgate should power open.
• If the liftgate will not open, refer to Liftgate Inoperative.
• If the liftgate latch releases but does not perform the power OPEN function, refer to Power Open Inoperative.
5. With the liftgate open, observe the scan tool Liftgate Rear Close Switch parameter while pressing and releasing the B70 liftgate close switch. The parameter should change from Inactive to Active.
• If the value does not change, refer to Liftgate Close Switch Inoperative.
6. Command the liftgate to power CLOSE pressing the open/close switch on the S58B Rear Compartment Lid Unlatch Switch - Interior. The liftgate should perform the power CLOSE function.
• If the liftgate does not power CLOSE, refer to Power Close Inoperative.
7. Manually open the liftgate and verify that the liftgate will remain at or near the full open position for several minutes.
• If the liftgate will not remain open, replace the liftgate struts.
Circuit/System Testing
Interior Liftgate Control Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the S58B Rear Compartment Lid Unlatch Switch - Interior.
2. Test for less than 30 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 Liftgate Front Control Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the K39 liftgate control module.
4. Install a 3 A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool Liftgate Front Control 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 K39 liftgate control module.
5. Verify the scan tool Liftgate Mode Switch parameter is greater than 300 counts.
• If less than the specified range, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the K39 liftgate control module.
6. Connect a 3 A fused jumper wire between the signal circuit terminal 3 and ground, verify the scan tool Liftgate Mode Switch parameter is less than 5 counts.
• If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K39 liftgate module.
7. If all circuits test normal, test or replace the S45B liftgate control switch - interior.
Liftgate Handle Switch Inoperative
1. Ignition OFF, disconnect the harness connector at the S46 liftgate handle switch.
2. Test for less than 30 ohm between the low reference circuit terminal 2 and ground.
• If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K39 liftgate module.
3. Ignition ON, verify the scan tool Liftgate Handle 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 K39 liftgate module.
4. Connect a 3 A fused jumper wire between the signal circuit terminal 1 and ground, verify the scan tool Liftgate Handle 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 K39 liftgate module.
5. If all circuits test normal, test or replace the S46 liftgate handle switch.
Liftgate Inoperative
1. Ignition OFF, disconnect the X1 harness connector at the K39 liftgate control module.
2. Test for less than 30 ohm between the ground circuit terminal 6 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminals listed below and ground.
* B+ terminal 3
* B+ terminal 4
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Test for less than 15 ohm between the control circuit terminal 1 and the control circuit terminal 2.
• If greater than the specified range, test either control circuit for a short to voltage or an open/high resistance. If circuits test normal, test or replace the M31 liftgate latch assembly.
5. Verify that a test lamp does not illuminate between the control circuit terminal listed below and B+.
* Control circuit terminal 1
* Control circuit terminal 2
• If the test lamp illuminates, test the control circuit for a short to ground. If circuit tests normal, test or replace the M31 liftgate latch assembly
6. If all circuits test normal test or replace the M31 liftgate latch assembly.
Liftgate Close Switch Inoperative
1. Ignition OFF, disconnect the harness connector at the B70 liftgate close switch.
2. Test for less than 30 ohm between the low reference circuit terminal 4 and ground.
• If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K39 liftgate module.
3. Ignition ON, verify the scan tool Liftgate Rear Close Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the K39 liftgate module
4. Connect a 3 A fused jumper wire between the signal circuit terminal 3 and ground, verify the scan tool Liftgate Rear Close 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 K39 liftgate module.
5. If all circuits test normal, test or replace the B70 liftgate close switch.
Power Open Inoperative
1. Ignition OFF, disconnect the harness connector at the A23C liftgate latch assembly.
2. Test for less than 30 ohm between the low reference circuit terminal 2 and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K39 liftgate module.
3. Ignition ON, verify the scan tool LGM Latch Pawl Sw. parameter is Inactive.
• If not the specified value, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the K39 liftgate module
4. Install a 3A fused jumper wire between the signal circuit terminal 5 and low reference circuit terminal 2. Verify the scan tool LGM Latch Pawl 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 K39 liftgate module.
5. Verify the scan tool Liftgate Latch Ratchet Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the K39 liftgate module.
6. Install a 3 A fused jumper wire between the signal circuit terminal 6 and low reference circuit terminal 2. Verify the scan tool Liftgate Latch Ratchet 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 K39 liftgate module.
7. Verify the scan tool Liftgate Latch Sector Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the K39 liftgate module.
8. Install a 3 A fused jumper wire between the signal circuit terminal 4 and low reference circuit terminal 2. Verify the scan tool Liftgate Latch Sector 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 K39 liftgate module.
9. Ignition OFF, connect the harness connector at the A23C liftgate latch assembly.
10. Ignition ON, observe the scan tool LGM Latch Pawl Sw., LGM Latch Ratchet Sw and LGM Latch Ratchet Sw while opening and closing the liftgate. Each parameter should change for Inactive to active as the liftgate is opened and closed.
• If a value is always Inactive or always Active, test or replace the A23C liftgate latch assembly.
11. Ignition OFF, disconnect the harness connector at the M17 liftgate motor assembly
12. Test for less than 30k ohm between the control circuit terminal A and ground.
• If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K39 liftgate module.
13. Test for less than 30k ohm between the control circuit terminal B and ground
• If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K39 liftgate module.
14. Connect a test lamp between control circuit terminal A and control circuit terminal B
15. Ignition ON, with the liftgate open, command the liftgate to CLOSE by pressing the interior liftgate control switch. The test lamp should briefly illuminate when commanding the CLOSE state.
• If the test lamp is always OFF, test the control circuit terminal B for a short to ground. If the circuit tests normal, replace the K39 liftgate module.
16. With the liftgate closed, command the liftgate to OPEN by pressing the interior liftgate control switch. The test lamp should briefly illuminate when commanding the OPEN state
• If the test lamp is always OFF, test the control circuit terminal A for a short to ground. If the circuit tests normal, replace the K39 liftgate module.
17. If all circuits test normal, test or replace the M17 liftgate motor assembly.
Power Close Inoperative
1. Ignition OFF, disconnect the harness connector at the B71L liftgate object sensor - left.
2. Test for less than 30 ohm between the low reference circuit terminal B and ground.
• If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K39 liftgate module.
3. Disconnect the harness connector at the B71R liftgate object sensor - right.
4. Ignition ON, test for 4.75-5.25 V between the signal circuit terminal A and ground.
• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K39 liftgate module.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K39 liftgate module.
5. Test of infinite resistance between the signal circuit terminal B at the B71R liftgate object sensor - right and ground.
• If not the specified value, test the signal circuit for a short to ground
6. Test for less than 1 ohm between the signal circuit terminal B at the B71R liftgate object sensor - right and the signal circuit terminal A at the B71L liftgate object sensor - left.
• If greater than the specified range, test the signal circuit for an open/high resistance.
7. Test for 8k-12k ohm between the signal terminal A and the low reference terminal B at the B71R liftgate object sensor - right.
• If not within the specified range, replace the B71R liftgate object sensor - right
8. Test for 8k-12k ohm between the signal terminal A and the low reference terminal B at the B71L liftgate object sensor - left.
• If not within the specified range, replace the B71L liftgate object sensor - left.
9. If all circuits test normal, replace the B71L liftgate object sensor - left and the B71R liftgate object sensor - right.
Component Testing
Liftgate Handle Switch
1. Ignition OFF, disconnect the harness connector at the S46 liftgate handle switch.
2. Test for infinite resistance between the signal terminal 2 and the low reference terminal 1 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 2 and the low reference terminal 1 with the switch in the closed position.
• If greater than the specified range, replace the S46 liftgate handle switch.
Interior Liftgate Control Switch
1. Ignition OFF, disconnect the harness connector at the S58B Rear Compartment Lid Unlatch Switch - Interior.
2. Test for infinite resistance between the signal terminal 3 and the low reference terminal 4 with the liftgate open switch in the inactive position.
• If not the specified value, replace the S58B Rear Compartment Lid Unlatch Switch - Interior.
3. Test for less than 3 ohm between the signal terminal 3 and the low reference terminal 4 with the liftgate open switch in the active position.
• If greater than the specified range, replace the S58B Rear Compartment Lid Unlatch Switch - Interior.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Liftgate Latch Replacement (Service and Repair)
* Liftgate Hydraulic Actuator Replacement (Service and Repair)
* Liftgate Close Switch Replacement (Liftgate Close Switch Replacement)
* Rear Compartment Lid Release Switch Replacement (Rear Compartment Lid Release Switch Replacement)
* Liftgate Side Upper Sensor Replacement (Equinox) (Service and Repair)Liftgate Side Upper Sensor Replacement (Terrain) (Service and Repair)
* Liftgate Release Switch Replacement (Liftgate Release Switch Replacement)
* Control Module References (Programming and Relearning) for liftgate module replacement, setup and programming