Another Lift gate problem (solved itself)

[SpareParts]

I can't seem to figure out this FU*&)ing thing. Rear lift gate open message on DIC
I have replaced all the struts. 2 for glass and 2 for the gate.
I have replaced the Lift gate drive part on the lift gate motor. Lift gate motor does function.
I have replaced the Lock actuator on the door. Tried 1 new one and 2 used ones.
The switch on the outside handle is new and checks good. As did the old switch.
The window will open with the fob or button on the door.
Checked and cleaned the switch on the window latch. It tests good and functions as it should.

When I push the open button on the over head I can hear the module in the rear click but nothing happens.
When in auto mode, the tail lights flash when the fob button is pushed but nothing happens.
When in manual mode, pressing the switch on the outside I get nothing. Tail lights do not flash. Nothing happens.
The 15A fuse is good and continuity tested.

It's almost like the rear gate has no power but the glass part works as it should, so I would think the power is good.
The main wire plug for the tail gate is good with no burned connectors.

I guess the big clue here would be the tail lights not flashing when the outside switch is pressed?
I need some help with this as I'm at a total loss now on how to continue.
I can't seem to find a test procedure and this type of troubleshooting is not my strong point for sure.
Anyone offer so help?

 

[SpareParts]

The 15A fuse has no power to it when tested. If I put power to it, nothing happens either.

 

[mikez71]

Is it not opening because it thinks it's already open?
Maybe something to do with the liftgate sensors?

I think @Doubeleive has pictures of them.

What did you do to your NNBS GMT900 Tahoe/Yukon Today?

Knocked out the driver side valve cover gasket earlier. Wind picked up as I was finishing up so I didn't get to do an oil change. Gaskets on both sides were hard as a rock and very brittle. Came off in pieces while the hold down bolt grommets were also very brittle. Some were still flexible...

www.tahoeyukonforum.com

Here's a thread that shows the liftgate open wiring in BCM...

How to fix "rear doors open" or "liftgate open" instrument cluster messages

Hi Guys, This will be my last post here, as I no longer have a Tahoe. I thought I'd share the solution that took me a year to track down. Ever since I owned my Tahoe, I could not use the feature of having the interior lights come on when a door was opened, otherwise they would never turn off...

www.tahoeyukonforum.com

 

[swathdiver]

You should be getting a trouble code or two in the BCM. Take that code or two and run them through the troubleshooting guide in the shop manual.

Charm.ii for the freebie or AllDataDIY for a subscription.

 

[SpareParts]

The sensors on each side are for door obstructions. I had to research them after he posted that info about them. They could be unplugged and the door would still function.
The BCM the other post shows is for an older Tahoe, pre 2007 and nothing like my BCM.

Messed with it for a few hours this morning but not actually changing anything and just could not make it work no matter what combination I pushed switches.
Tried my scanner but it can only open the back glass. It can not work the rear lift gate and has no option for it
There are no codes in the BCM.

After 2 days of messing with it and getting frustrated it magically fixed itself. I have no idea why it started working or why it was not working.
It now opens with the remote, the inside switch and the rear gate switch. Tail lights also flash now.

 

[Fless]

You should be getting a trouble code or two in the BCM. Take that code or two and run them through the troubleshooting guide in the shop manual.

Charm.ii for the freebie or AllDataDIY for a subscription.

For the record, it's "charm.Li" (that's an 'el' after the period). The "li" domain is registered in Liechtenstein.