Liftgate will not electrically open or close

You will have to use the lift-gate trim panel plug to open it and then remove the lift-gate trim panel to inspect the latching mechanism. Try lubricating the latch with WD40 and see if that helps the issue.

Since the gate is opening manually you can easily remove the trim panel to access the motor. Before doing this though, you can check the fuse labeled LCK2 (15 amp), OBS DET (10 amp) and UNLCK2 (15 amp) all in the instrument panel fuse block located at the left side of the instrument panel behind the access panel.

If these fuses are good then the lift-gate release relay may be bad, unfortunately this is a printed circuit board (PCB) relay which means it is built into the fuse block, so if it is bad the entire block must be replaced. You said you hear a noise when pushing the button though, so I would assume that is the relay clicking. You can test the motor by supplying twelve volts direct power to it from a twelve volts source (i.E. Spare car battery). With twelve volts direct power and a ground, the motor should run without using a switch. If it does not run this way the motor is bad, if it does run then power is not getting to it.

If the lift-gate is not opening manually you will have to locate the dimple on the trim panel. Use a 1 1/16" drill bit to drill a hole through the trim panel in the dimple area. Use a flat blade tool (i.E. Screwdriver) to push down on the black bell-crank lever through the plug hole to unlock the lift-gate. Push open the lift-gate from the inside.

Hello,

What happens in these cars is the liftgate motor starts to go bad causing the amperage to be higher than the electronics are designed for so it burns them up there is also a control module that works the system as well.

Here are the wiring diagrams and repair manual diagrams to help you see how the system works. It sounds like the liftgate module is bad. Check out the diagrams (Below) Please let us know what happens. Cheers, Ken

If it was recently repaired then it needs to be calibrated. It may need to be scanned by a pro to see if a sensor is bad however. See pics.

They probably did not calibrate the lift-gate, there is a tsb on this, its number is 06008a if it was done at a dealer I would take it back and have them fix it or call GMC they will see that is gets fixed. There is an updated version for calibration as well.

The picture is a posting of a tip other mechanics have run into so it's in addition to the tsb. The local mechanic may not be able to do either of these so you'll have to talk it over this may have to be done at a dealer.

For the door locks have it scanned it may be body module problem could also be a relay in dash. Fuse box. Also check unlock fuse 2 as well. For the seat there is a tsb on this so it has to have the harness rerouted and fixed if cut but you need to take the seat off the floor to do this. It needs a special tape to ifx this along with rerouting it. Not sure if a dealer wil stil do this on your car they may however so check

Sounds like the gas struts are weak. They assist the system by lowering the amount of weight the motor sees. If they are faulty the sensors see excessive weight and think you are closing the gate. Replace the gas struts and the problem should be repaired.

It is quite possibly just a weak support strut. Look for leakage on either of the struts. The lift system requires the assistance from the struts to complete an opening. The excess weight of the door, without the assistance of the struts, causes false reversal.

I had a similar problem with a different brand vehicle, and fixed it by readjusting the striker. Seems the gate has to pop open far enough to leave the striker. When it's misadjusted, the gate doesn't pop open far enough and the latch is still touching the striker. That creates the signal that it's supposed to be pulling closed. Adjust the striker forward about 1/8" and try it.