Back liftgate not working properly wiring schematic needed

Tiny
JEFFREY RADER
  • MEMBER
  • 2007 GMC ACADIA
  • 220,000 MILES
Liftgate will not open or close on its own work's okay manually.
Has no problem locking or unlocking have tried key fob and override button on dash and hatch button all 3 will unlock hatch without a problem.
You can hear what sounds like the motor running win either opening or closing manually.
Wednesday, November 18th, 2020 AT 3:49 PM

6 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

I need to clarify something. Is the problem with the automatic rear liftgate not opening and closing or the power lock to the liftgate isn't working?

The power liftgate (open/close) is actuated by an electric motor which is attached to a p gear. If the gear has broken or is damaged, it may explain why you hear the motor running but the door not responding.

If that is the issue, here are the diagnostics for testing.

POWER LIFTGATE INOPERATIVE
1. Ignition OFF, disconnect the harness connector at the PLGM.
2. Ignition OFF, test for 1 ohm of resistance between the ground 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 terminal 3 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the PWR L/GATE fuse is open, replace the PLGM.

__________________________

I attached a couple of pics below showing the motor and wiring connector. Let me know if this is the problem you are having or if it is related to the lock itself.

Let me know.
Joe
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Wednesday, November 18th, 2020 AT 7:24 PM
Tiny
JEFFREY RADER
  • MEMBER
  • 3 POSTS
Power lock works fine. Lift gate not opening or closing on its own.
Thanks for the info will perform wiring test ASAP.
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Wednesday, November 18th, 2020 AT 10:24 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

I thought that was what you were referring to. Try the test listed above and if possible, let me know the result.

Joe
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Thursday, November 19th, 2020 AT 6:22 PM
Tiny
JEFFREY RADER
  • MEMBER
  • 3 POSTS
We'll do sir.
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Thursday, November 19th, 2020 AT 6:42 PM
Tiny
JEFFREY RADER
  • MEMBER
  • 3 POSTS
Joe, finally had time to do test on power lift-gate motor. Had exactly 1ohm at pin 6 on ground with ignition off and test light lit up with key position on at harness. Guess I'll be buying a wiring diagram now? Can you get one? Thanks for all the great info.
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Sunday, December 6th, 2020 AT 8:14 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

Take a look at the attached pics. It shows the wiring for the tailgate (automatic). I had to cut the pic in two so you could read it. But I did overlap them so you could follow it.

Let me know if this helps.

Take care,
Joe
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Sunday, December 6th, 2020 AT 9:52 PM

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