Power Liftgate System: Notes
In order to obtain conclusive testing of the power liftgate system, the controller area network 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.
Refer to appropriate Wiring Diagram for complete circuit schematic or connector pin out information.
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.
| 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 . 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 the appropriate wiring diagram information. Refer to appropriate Wiring Diagram. | |
| Power liftgate control module. | Check for diagnostic trouble codes and cycle with scan tool. Replace module if necessary. Refer to REMOVAL AND INSTALLATION . | |
| 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. Refer to REMOVAL AND INSTALLATION . | ||
| Failure of power liftgate drive unit. | Check for diagnostic trouble codes and cycle with scan tool. Replace power liftgate drive unit if necessary. Refer to REMOVAL AND INSTALLATION . | |
| 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 . 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 in ignition. | |
| Failure of key fob. | Reprogram key fob. Replace if necessary. | |
| Failure of wireless control module. | Check for DTCs and cycle liftgate with scan tool. Replace inoperative module as necessary. Refer to DOOR CONTROL MODULE . | |
| Wiring problems (system or vehicle). | Troubleshoot using the appropriate wiring diagrams information. Refer to appropriate Wiring Diagram. | |
| Controller area network data bus issue. | Refer to ELECTRICAL EQUIPMENT | |
| Power liftgate control module. | Check for diagnostic trouble codes and cycle with scan tool. Replace module if necessary. Refer to REMOVAL AND INSTALLATION . | |
| 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 . 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. | Check the overhead console switch. | |
| Wiring problems (system or vehicle). | Troubleshoot using the appropriate wiring diagrams information. Refer to appropriate Wiring Diagram. | |
| Power liftgate control module. | Check for diagnostic trouble codes and cycle with scan tool. Replace module if necessary. Refer to REMOVAL AND INSTALLATION . | |
| 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 . 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 and Installation . | |
| 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. Refer to REMOVAL AND INSTALLATION . | ||
| Wiring problems (system or vehicle). | Troubleshoot using the appropriate wiring diagrams information. Refer to appropriate Wiring Diagram. | |
| 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. Refer to REMOVAL AND INSTALLATION . | |
| 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 pressed 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 . 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 the appropriate wiring diagrams information. Refer to appropriate Wiring Diagram. | |
| 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 . 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 the appropriate wiring diagrams information. Refer to appropriate Wiring Diagram. | |
| 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 . 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 the appropriate wiring diagrams information. Refer to appropriate Wiring Diagram. | |
| 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 the appropriate wiring diagrams information. Refer to appropriate Wiring Diagram. | |
| 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. Refer to REMOVAL AND INSTALLATION . | ||
| Power liftgate control module. | Check for diagnostic trouble codes and cycle with scan tool. Replace module if necessary. Refer to REMOVAL AND INSTALLATION . | |
| 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 the appropriate wiring diagrams information. Refer to appropriate Wiring Diagram. | |
| Failure of full open switch. | Check switch status with scan tool. Replace switch if necessary. Refer to REMOVAL AND INSTALLATION . | |
| Failure of power liftgate drive unit. | Check for diagnostic trouble codes and cycle with scan tool. Replace power liftgate drive unit if necessary. Refer to REMOVAL AND INSTALLATION . | |
| Power liftgate control module. | Check for diagnostic trouble codes and cycle with scan tool. Replace module if necessary. Refer to REMOVAL AND INSTALLATION . | |
| 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 power liftgate module activation history. |
| Power liftgate system inhibitors preventing operation. | Check inhibit monitors with scan tool. Refer to POWER LIFTGATE SYSTEM INHIBIT MONITORS . 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 the appropriate wiring diagrams information. Refer to appropriate Wiring Diagram. | |
| 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. Refer to REMOVAL AND INSTALLATION . | ||
| Power liftgate control module. | Check for diagnostic trouble codes and cycle with scan tool. Replace module if necessary. Refer to REMOVAL AND INSTALLATION . |
Power Liftgate System Control Parameters
The power liftgate system is designed with a number of control parameters, which are conditions that must be fulfilled to allow operation. These control parameters are listed below:
- The power liftgate module will inhibit operation of the power liftgate in extreme temperatures. These temperatures will be approximately -22 °F (-30 °C) and 149 °F (65 °C). The pinch sensor/thermistor assembly on the right side of the liftgate monitors the temperature.
- The vehicle's transmission must be in park or neutral for the power liftgate to operate.
- The vehicle's speed must be zero for the power liftgate to operate.
- The vehicle's electrical system voltage must be within specification for the power liftgate system to operate. A low voltage cut off is built into the power liftgate system to prevent the vehicle's battery from discharging to the point were the vehicle cannot be operated.
- If the vehicle's ignition switch is in the START position, the power liftgate system will not initiate a power cycle.
- If the vehicle's ignition switch is moved to the START position during a power cycle, the power liftgate will pause.
- If the vehicle is locked, the outside handle will not release the latch. The key fob and overhead switch will work for power open or close cycles.
- If the vehicle's theft alarm is armed, the overhead switch will not open the liftgate; however the key fob will work.
- If a liftgate pinch sensor is activated during a power close, the liftgate will reverse direction. If a pinch sensor is already active the power liftgate will not initiate a power close. A pinch activation during latch cinch will stop the cinch operation.
- If something sufficiently impedes liftgate travel, the power liftgate will detect an obstacle and reverse direction, traveling to full open or closed.
- If multiple obstacles are detected during the same power open or close cycle, the liftgate will abort that power cycle and go into full manual operation.
- The power liftgate components are protected by the power liftgate fuse. If the fuse is blown, the power liftgate will not function.
- If severe DTCs are stored in the power liftgate control module the system may not operate. If power liftgate DTCs are present, refer to BODY EXTERIOR DTC BASED DIAGNOSTICS (1 OF 5) (B164B TO B19E7) .