Diagnosis And Testing - Power liftgate System
The power liftgate system is a complex system containing many components. In order to perform conclusive testing, or receive outputs the power liftgate control module must be checked.
The most reliable, efficient, and accurate means to diagnose the power liftgate system requires the use of a GDS. The GDS can be used to observe current switch status recorded in the power liftgate control module to help the technician diagnose an inoperative switch.
Before any testing of the power liftgate system is attempted, the battery should be fully charged, all power liftgate system inhibitors read and understood (Refer to power liftgate system description for list).
Following are quick reference diagnostic tables to help when diagnosing and testing the power liftgate system.
| CONDITION | POSSIBLE CAUSES | CORRECTION |
|---|---|---|
| Tailgate opens unexpectedly | Accidental activation or Failure of open/close command switch | Check for shorted or defective switch |
| Failure of latch assembly | Check wiring connections | |
| Check for trouble codes, replace latch if necessary | ||
| Failure of Power Tailgate or Body Control module | Disconnect then reconnect battery or fuse to reset module, function tailgate, if no function exists check for loose wire connections, see Body Diagnostic Manual for detailed procedures | |
| Tailgate will not power open or close | Not in Park or false indication | Check switch status with SCAN tool |
| Battery voltage at PTGM is too low | Check for proper voltage at the PTGM Charge battery |
|
| Blown fuse | Check for blown fuse | |
| Gas strut failure | Check condition of tailgate gas struts | |
| BCM or tailgate control module critical fault codes | Check code status with SCAN tool | |
| Failure of latch assembly | Check wire connections and for blown fuse | |
| Check for foreign matter preventing the operation of latch assembly | ||
| Tailgate will not power open or close | Failure of motor assembly | Test motor assembly |
| Binding or sticking of components | Establish location of binding and replace necessary components | |
| Wiring problems (system or vehicle) | Troubleshoot using electrical schematics Refer to the appropriate wiring diagrams | |
| Power loss during Tailgate operation | Wiring problems (system or vehicle) | Troubleshoot using electrical schematics. Refer to the appropriate wiring diagrams |
| Battery voltage at PTGM is too low | Check for proper voltage at the PTGM Charge battery |
|
| Failure of Power Tailgate or Body Control Module | Check for diagnostic trouble codes with SCAN tool | |
| Failure of motor assembly | Test motor assembly | |
| No power latching in primary and/or secondary positions | Failure of latch assembly | Check wire connections and for blown fuse |
| Check for diagnostic trouble codes and cycle with SCAN tool | ||
| Troubleshoot using Body Diagnostic Manual. Replace latch assembly, if necessary | ||
| Binding or sticking of components | Establish location of binding and replace necessary components | |
| Failure of Power Tailgate or Body Control Module | Check for diagnostic trouble codes with scan tool | |
| Tail Gate seal force too high | Inspect seals for damage, mis-assembly, foreign matter or other possible obstruction | |
| Failure of motor assembly | Test motor assembly | |
| Latch will not release from primary position | Not in Park or false indication | Check switch status with SCAN tool |
| Battery voltage at PTGM is too low | Check for proper voltage at the PTGM Charge battery |
|
| Key fob or overhead console switch does not power operate tailgate | Blown fuse | Check fuse and replace if required |
| Failure of latch assembly | Check switch status with scan tool | |
| Check for foreign matter or damaged components preventing the operation of latch assembly | ||
| Troubleshoot using body diagnostic manual. Replace latch assembly, if necessary |
||
| Failure of outside handle connection | Check handle of brainplate. | |
| Failure of Power Tailgate or Body Control Module | Check for diagnostic trouble codes and cycle with scan tool | |
| Binding or sticking of components | Establish location of binding and replace necessary components | |
| Blown Fuse | Check fuse and replace | |
| Battery voltage at PTGM is too low | Check for proper voltage at the PTGM Charge battery |
|
| Does Not Power Unlatch | Failure of latch assembly | Check for foreign matter preventing the operation of latch assembly |
| Check for diagnostic trouble codes and cycle with scan tool | ||
| Check pawl and/or ratchet switch with SCAN tool | ||
| Troubleshoot using body diagnostic manual | ||
| Does Not Power Unlatch | Failure of Power Tailgate Module | Troubleshoot using body diagnostic manual |
| Failure of Body Control Module (BCM) | Troubleshoot using body diagnostic manual | |
| Replace BCM if necessary | ||
| Failure of key fob | Reprogram key fob | |
| Replace key fob if necessary | ||
| Failure of Power Tailgate Module | Check for diagnostic trouble codes with scan tool, see Body Diagnostic Manual for detailed procedures | |
| Failure of tailgate motor assembly | Check for foreign matter preventing the operation of motor assembly | |
| Check wire connections | ||
| Motor clutch does not engage, replace assembly | ||
| Full open switch inoperative, replace switch, if necessary | ||
| Troubleshoot using Body Diagnostic Manual Replace motor, if necessary | ||
| Tailgate does not stay open | Failure of tailgate gas struts | Replace gas struts |
| Check for broken attachments | ||
| High inside/outside opening effort | Failure of tailgate gas spindle | Replace gas spindle |
| Check for broken attachments | ||
| Drive unit jammed or did not disengage | Troubleshoot using Body Diagnostic Manual Replace components, if necessary |
|
| Binding or sticking of components | Establish location of binding and replace necessary components | |
| Tailgate continues to cinch closed | Failure of latch assembly | Check wire connections and for blown fuse Check switches with SCAN tool |
| Tail gate continues to power close | Failure of latch assembly | Check wire connections |
| Check for foreign matter | ||
| Troubleshoot using Body Diagnostic Manual | ||
| Control Module | Check for diagnostic trouble codes with Scan tool | |
| Wiring problems (system or vehicle) | Troubleshoot using electrical schematics Refer to the appropriate wiring diagrams |
|
| Tailgate continues to power open | Failure of PTGM or BCM | Check for diagnostic trouble codes and cycle, see Body Diagnostic Manual for detailed procedures |
| Failure of motor assembly | Check for continuous drive condition | |
| Wiring problems (system or vehicle) | Troubleshoot using electrical schematics Refer to the appropriate Wiring Diagrams | |
| Tailgate opens very slowly | Battery voltage at PTGM is too low | Check for proper voltage at the PTGM Charge battery |
| Failure of tailgate gas struts | Replace gas struts, if necessary | |
| Binding or sticking of components | Establish location of binding and replace necessary components | |
| Grade of vehicle too steep for power operation | Operate tailgate manually | |
| Failure of tailgate motor assembly | Replace motor assembly, if necessary | |
| Squeaks, Noises and rattles | Foreign material in tail gate compartment | Remove foreign material |
| Worn/Loose components | Check and tighten loose components |