Power Liftgate System: Notes
In order to obtain conclusive testing of the power liftgate system, the Controller Area Network (CAN) data bus, and all of the electronic modules that provide inputs to, or receive outputs from the power liftgate system components must be checked. Any diagnosis of the power liftgate system should begin with, the use of a scan tool and the appropriate diagnostic service information.
For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article. Also refer to CONNECTOR PIN-OUT article as needed.
NOTE:
Before any testing of the power liftgate system is attempted, the battery should be fully-charged.
Following are quick reference diagnostic tables to help when diagnosing and testing the power liftgate system.
SYMPTOM DRIVEN POWER LIFTGATE SYSTEM DIAGNOSIS TABLE
| CONDITION | POSSIBLE CAUSES | CORRECTION |
|---|---|---|
| LIFTGATE WILL NOT INITIATE POWER OPEN/POWER CLOSE WITH EITHER KEY FOB OR OVERHEAD CONSOLE SWITCH | Power Liftgate System Inhibitors preventing operation | Check Inhibit Monitors with scan tool. Refer to POWER LIFTGATE SYSTEM INHIBIT MONITORS TABLE , repair as required. |
| Power Liftgate Input/Output status incorrect | Check power liftgate input - output status with scan tool. Refer to POWER LIFTGATE INPUT - OUTPUT TABLE , repair as required | |
| Binding or sticking of components | Establish location of binding and repair components if necessary | |
| Wiring problems (system or vehicle) | Troubleshoot using wiring diagrams information, For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article | |
| Power Liftgate Control Module | Check for diagnostic trouble codes and cycle with scan tool, replace module if necessary | |
| Failure of latch assembly | Check for foreign matter or damaged components preventing the operation of latch assembly | |
| - | Check for diagnostic trouble codes and cycle with scan tool, replace latch if necessary | |
| Failure of power liftgate drive unit | Check for diagnostic trouble codes and cycle with scan tool, replace power liftgate drive unit if necessary | |
| KEY FOB DOES NOT OPERATE POWER LIFTGATE (BUT OVERHEAD CONSOLE SWITCH DOES) | Power Liftgate System Inhibitors preventing operation | Check Inhibit Monitors with scan tool. Refer to POWER LIFTGATE SYSTEM INHIBIT MONITORS TABLE , repair as required. |
| - | Power Liftgate Input/Output status incorrect | Check power liftgate input - output status with scan tool. Refer to POWER LIFTGATE INPUT - OUTPUT TABLE , repair as required |
| - | Key in ignition | Key fob buttons do not function when key is ignition |
| - | Failure of key fob | Reprogram key fob, replace if necessary |
| - | Failure of Wireless Control Module (WCM) | Check for diagnostic trouble codes and cycle liftgate with scan tool, replace inoperative module as necessary |
| - | Wiring problems (system or vehicle) | Troubleshoot using wiring diagrams information, For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article |
| - | Controller Area Network (CAN) Data Bus issue | Refer to the ELECTRONIC CONTROL MODULES - ELECTRICAL DIAGNOSTICS article |
| - | Power Liftgate Control Module | Check for diagnostic trouble codes and cycle with scan tool, replace module if necessary |
| OVERHEAD CONSOLE SWITCH DOES NOT OPERATE POWER LIFTGATE (BUT KEY FOB DOES) | Power Liftgate System Inhibitors preventing operation | Check Inhibit Monitors with scan tool. Refer to POWER LIFTGATE SYSTEM INHIBIT MONITORS TABLE , repair as required. |
| - | Power Liftgate Input/Output status incorrect | Check power liftgate input - output status with scan tool. Refer to POWER LIFTGATE INPUT - OUTPUT TABLE , repair as required |
| - | Failure of overhead console switch | See DIAGNOSIS AND TESTING . |
| - | Wiring problems (system or vehicle) | Troubleshoot using wiring diagrams information, For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article |
| - | Power Liftgate Control Module | Check for diagnostic trouble codes and cycle with scan tool, replace module if necessary |
| LATCH WILL NOT RELEASE WITH OUTSIDE HANDLE (POWER-OPEN CYCLE MAY OR MAY NOT INITIATE) | Power Liftgate System Inhibitors preventing operation | Check Inhibit Monitors with scan tool. Refer to POWER LIFTGATE SYSTEM INHIBIT MONITORS TABLE , repair as required. |
| - | Power Liftgate Input/Output status incorrect | Check power liftgate input - output status with scan tool. Refer to POWER LIFTGATE INPUT - OUTPUT TABLE , repair as required |
| - | Failure of outside handle/linkage | Refer to REMOVAL . |
| - | Failure of outside handle switch | Check for diagnostic trouble codes and cycle with scan tool, repair as required |
| - | Failure of latch assembly | Check for foreign matter or damaged components preventing the operation of latch assembly |
| - | - | Check for diagnostic trouble codes and cycle with scan tool, replace latch if necessary |
| - | Wiring problems (system or vehicle) | Troubleshoot using wiring diagrams information, For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article |
| - | Binding or sticking of components | Establish location of binding and replace necessary components |
| - | Power Liftgate Control Module | Check for diagnostic trouble codes and cycle with scan tool, replace module if necessary |
| LIFTGATE REVERSES DIRECTION DURING POWER OPEN/POWER CLOSE CYCLE | Key fob button being hit more than the two times required, or overhead console switch being hit more than once Extra presses may cause the liftgate to reverse direction | Key fob button being hit more than the two times required, or overhead console switch being hit more than once Extra presses may cause the liftgate to reverse direction |
| - | Power Liftgate System Inhibitors preventing operation | Check Inhibit Monitors with scan tool. Refer to POWER LIFTGATE SYSTEM INHIBIT MONITORS TABLE , repair as required. |
| - | Power Liftgate Input/Output status incorrect | Check power liftgate input - output status with scan tool. Refer to POWER LIFTGATE INPUT - OUTPUT TABLE , repair as required |
| - | Binding or sticking of components | Establish location of binding and replace necessary components |
| - | Wiring problems (system or vehicle) | Troubleshoot using wiring diagrams information, For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article |
| - | Failure of power liftgate drive unit | Check for diagnostic trouble codes and cycle with scan tool, replace power liftgate drive unit if necessary |
| - | Power Liftgate Control Module | Check for diagnostic trouble codes and cycle with scan tool, replace module if necessary |
| LATCH WILL NOT POWER-CINCH TO PRIMARY POSITION (DURING MANUAL AND/OR POWER OPERATION) | Power Liftgate System Inhibitors preventing operation | Check Inhibit Monitors with scan tool. Refer to POWER LIFTGATE SYSTEM INHIBIT MONITORS TABLE , repair as required. |
| - | Pinch sensor activated or open/short circuit | Check pinch sensor status with scan tool. Repair as required. |
| - | Power Liftgate Input/Output status incorrect | Check power liftgate input - output status with scan tool. Refer to POWER LIFTGATE INPUT - OUTPUT TABLE , repair as required |
| - | Binding or sticking of components | Establish location of binding and replace necessary components |
| - | Door seal force too high | Inspect seals for damage, improper installation, foreign matter or other possible obstruction. Repair as required |
| - | Wiring problems (system or vehicle) | Troubleshoot using wiring diagrams information, For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article |
| - | Failure of latch assembly | Check for foreign matter or damaged components preventing the operation of latch assembly |
| - | - | Check for diagnostic trouble codes and cycle with scan tool, replace latch if necessary |
| - | Power Liftgate Control Module | Check for diagnostic trouble codes and cycle with scan tool, replace module if necessary |
| LIFTGATE DOES NOT STAY OPEN AFTER COMPLETION OF POWER-OPEN CYCLE AND/OR MANUAL OPENING | Failure of liftgate strut-supports (prop rods) | Check for broken attachments |
| - | - | Replace prop rods |
| HIGH OPENING EFFORT/LIFTGATE OPENS VERY SLOWLY DURING MANUAL AND/OR POWER OPERATION | Power Liftgate System Inhibitors preventing operation | Check Inhibit Monitors with scan tool. Refer to POWER LIFTGATE SYSTEM INHIBIT MONITORS TABLE , repair as required. |
| - | Failure of liftgate strut-supports (prop rods) | Check for broken attachments |
| - | - | Replace prop rods |
| - | Binding or sticking of components | Establish location of binding and replace necessary components |
| - | Wiring problems (system or vehicle) | Troubleshoot using wiring diagrams information, For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article |
| - | Grade of vehicle too steep for power operation | Operate liftgate manually |
| - | Failure of power liftgate drive unit | Check for diagnostic trouble codes and cycle with scan tool, replace power liftgate drive unit if necessary |
| LIFTGATE CONTINUES TO POWER-CLOSE AFTER REACHING FULL-CLOSED POSITION | Power Liftgate Input/Output status incorrect | Check power liftgate input - output status with scan tool. Refer to POWER LIFTGATE INPUT - OUTPUT TABLE , repair as required |
| - | Wiring problems (system or vehicle) | Troubleshoot using wiring diagrams information, For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article |
| - | Binding or sticking of components | Establish location of binding and replace necessary components |
| - | Failure of latch assembly | Check for foreign matter or damaged components preventing the operation of latch assembly |
| - | - | Check for diagnostic trouble codes and cycle with scan tool, replace latch if necessary |
| - | Power Liftgate Control Module | Check for diagnostic trouble codes and cycle with scan tool, replace module if necessary |
| LIFTGATE CONTINUES TO POWER-OPEN AFTER REACHING FULL-OPEN POSITION (MAY PULSE SEVERAL TIMES) | Power Liftgate Input/Output status incorrect | Check power liftgate input - output status with scan tool. Refer to POWER LIFTGATE INPUT - OUTPUT TABLE , repair as required |
| - | Wiring problems (system or vehicle) | Troubleshoot using wiring diagrams information, For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article |
| - | Failure of full open switch | Check switch status with scan tool, replace switch if necessary |
| - | Failure of power liftgate drive unit | Check for diagnostic trouble codes and cycle with scan tool, replace power liftgate drive unit if necessary |
| - | Power Liftgate Control Module | Check for diagnostic trouble codes and cycle with scan tool, replace module if necessary |
| SQUEAKS, NOISES AND RATTLES | Foreign material inside liftgate panel | Remove foreign material |
| - | Worn/loose components | Check and tighten/replace loose components |
| LIFTGATE UNLATCHES OR INITIATES POWER OPEN/POWER CLOSE CYCLE UNEXPECTEDLY | Accidental activation | Use scan tool to check/record PLGM activation history |
| - | Power Liftgate System Inhibitors preventing operation | Check Inhibit Monitors with scan tool. Refer to POWER LIFTGATE SYSTEM INHIBIT MONITORS TABLE , repair as required. |
| - | Power Liftgate Input/Output status incorrect | Check power liftgate input - output status with scan tool. Refer to POWER LIFTGATE INPUT - OUTPUT TABLE , repair as required |
| - | Wiring problems (system or vehicle) | Troubleshoot using wiring diagrams information, For complete circuit diagrams, refer to the SYSTEM WIRING DIAGRAMS article |
| - | Failure of key fob button or overhead console switch | Check for shorted or defective switch |
| - | Failure of latch assembly | Check for foreign matter or damaged components preventing the operation of latch assembly |
| - | - | Check for diagnostic trouble codes and cycle with scan tool, replace latch if necessary |
| - | Power Liftgate Control Module | Check for diagnostic trouble codes and cycle with scan tool, replace module if necessary |