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2021 Yukon Denali Power Liftgate Intermittent Failure

0

Christine P. · rep 0 · May 22, 3:42 AM · 1 replies · solved · Question

Vehicle: 2021 GMC Yukon Denali

Hi everyone,

I'm having a frustrating issue with the power liftgate on my 2021 GMC Yukon Denali. It's been working perfectly fine since I got the truck, but recently it's started acting up. Sometimes it opens and closes without a hitch, but other times it just won't respond to the button on the key fob, the dash, or even the button on the liftgate itself.

When it fails, there's no sound, no attempt to move, just nothing. Then, later, it might work perfectly again for a few cycles. I've checked for obstructions, but there's nothing in the way. It's really inconvenient, especially when my hands are full.

Could this be a sensor issue, a module problem, or maybe a motor going bad? Any ideas on what to look for?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:42 AM

0

ClearTheCode admin answer:

Intermittent failure of a power liftgate on a newer vehicle like your 2021 GMC Yukon Denali can be particularly vexing, as it often points to an electrical control issue rather than a purely mechanical one. Given the 'no response' symptom, here are the most common areas to investigate:

  1. Power Liftgate Control Module (PLGM): This module is the brain of the system. An intermittent fault within the module itself, or a power/ground supply issue to the module, could cause it to stop responding. Sometimes, a simple reset (disconnecting the battery for 15-30 minutes) can temporarily resolve module glitches.
  2. Wiring Harness and Connectors: Inspect the wiring harness that runs to the liftgate motor, latch, and control buttons. Pay close attention to areas where the harness flexes when the liftgate opens and closes (e.g., near the hinges). A broken or frayed wire in this area is a very common cause of intermittent operation.
  3. Liftgate Latch Assembly: The latch assembly contains sensors that tell the PLGM if the liftgate is fully closed or open. A faulty sensor within the latch can sometimes prevent operation, as the system might think the gate is already open or closed incorrectly.
  4. Liftgate Motor/Actuator: While a complete motor failure usually results in no operation at all, an intermittent motor issue (e.g., worn brushes, internal short) could cause the symptoms you describe. However, the 'no sound, no attempt' suggests a control issue before the motor even tries to engage.
  5. Button/Switch Issues: Less likely if all three buttons (fob, dash, liftgate) fail simultaneously, but individual button failures can occur. If only one button fails, that's a good place to start.
    • Common OBD-II Codes: While not always triggering a check engine light, a scan tool capable of reading body control module (BCM) and PLGM codes might reveal U-codes (communication errors) or B-codes (body system faults) related to the liftgate system.

When to See a Shop:

  • If a battery reset doesn't help, or if you're uncomfortable inspecting wiring harnesses, it's best to take your Yukon to a GMC dealership or a reputable auto electrical specialist.
  • They have specialized diagnostic tools to communicate with the PLGM, read specific fault codes, and perform pinpoint tests on the wiring and components to accurately diagnose the intermittent fault.
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