Barry_A

I have a 2007 Tahoe, and for some reason the rear lift gate will no longer lift on its own. Can anyone tell me how this lift function actually works.
When I press the button for it to open the door, I can hear somthing run inside the liftgate itself. I assume this is unlocking the Lock. Then I can hear the LIft motor engage, but it will suddenly makes a slight clunk sound and stops.
I can manualy open the liftgate by hand and it opens very easy. If I go to close it from the full open position, I can hear the lift motor start but then I hear a slight clunk again and the motor will stop.
I have to assume it has something to do with the lift motor. Anybody have any ideas. Also, does anyone know how to remove the interior rear panel to access the lift motor?

73shark

Don't know how it works but it sounds like something in the linkage has either broke or become disconnected. You'd have to remove the interior panel to check.

Barry_A

I finally figured out how to get to the motor assmbly. Now the question is what could be wrong with it. The assembly has 2 switches on it, a motor, and a control module. I have removed the motor assebly from the vehicle, and have removed the control module from the assembly and put it back in the tahoe so I can use the back door for now. Does anyone have a wiring diagram for the rear left lift gate switches and the motor assembly? Since there is a control board on the motor assmebly, I would assume there could be numerous things that could cause the rear motor not to opperate. I would like to test the motor, but there are 5 wires going to the motor, I do not know which wires do what so I can not test the motor. Any help would be appreciated

73shark

Did you try it before you removed it from the truck?

Barry_A

Yeah, I unhooked the rod from the back door, and tried to make it work when it did not have to lift the door. I even pushed and pulled on the arm to see if i Could get it to move while i activated it, and I could not get anything out of the motor. The motor did not even seem to try to push or pull the gears. By the way, the gears move very easliy. I can rotate them all the way to the closed and open position without any problems.

73shark

If you are getting power to the motor and it's not running, then I'll go out on a limb and say it's probably the motor.

Barry_A

I can not tell if the motor is actually running. I have taken the motor off of the assembly and i am going to plug it into the computer board and see if it runs, however, there are several control switchs that have to be unpluged to get the motor off of the assmbly. that are all linked to the motor and the computer control board. I can not be for sure that since all of the switchs etc.. are not hooked up that it will actually work that way.
I am hoping that someone can tell me which of the six wires that go to the motor are positive and negative so I can test the motor. Here are the colors of the wires going to the motor. One Large -Brown w/White stirpe wire, One Large White Wire, One Small LT blue w/White stripe wire, one Small green w/white stripe wire, one small purple wire, and one small Black w/white stipe wire.

Barry_A

anybody have access to the wiring diagram for the 2007 Tahoe Power liftgate? See wire colors above.

KMeloney

You sound like a do-it-yourselfer who wants to get to the bottom of this problem on your own. But, I know that my brother-in-law's '07 Sub's rear liftgate just broke, and he had it replaced (under warranty, I think). On his, one of the struts' mounting posts broke, and the liftgate wouldn't open. Seems to me that they replaced the whole assembly, including the motor.

Barry_A

Thanks for the info. Unfortunatly my tahoe is beyond the manufactures warranty, and I do not have the extended warranty. I love working on these type of issues and repairing them myself so that is one reason I opt out of the extended warranty. Unfortunatly the liftgate can have several things that can trigger it not to function properly, and with out a wiring schematic it is very difficult to trouble shoot the exact problem. I was hoping that someone on here would have access to that schematic, or point me in the right direction.
As a last resort, I will just start replacing part by part until I get it fixed, but that can get very expensive quick. I have chilton manuals form my 2003 Silverado, and it has the wiring schematics in it for that truck. I can not find where they have publshed the 2007 and newer book yet. Does anybody know if it is available?