Another Lift gate problem

[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.

 

[SpareParts]

After researching code B2495 (Lift gate latch control circuit) and finding very little info about it seems the most likely problem is the main tail gate plug.
It does act like a wiring problem.
I had the main plug apart once and looked at the pins and they all looked good but maybe I missed something.
I'm going to start troubleshooting from that plug. Maybe the power pin is stretched and not making a good connection.

 

[SpareParts]

I can't seem to find a wiring diagram I can make sense of, but then again, I'm just about noob level when it comes to wiring.
Does anyone have the procedure for testing the lift gate module and wiring? I think that is what I need.
The diagram I can figure out I'm sure but it only shows where the wires come from and go to.

 

[SpareParts]

Either the motor was burned up or the module was bad on the original unit. I don't know what one as i could not find a test procedure for either.
I put an entire mechanism, module from a 2010 Escalade on it and a new clutch on it and it now works every time. The rear close switch never worked either but now it even does.
So finally got another annoying problem fixed.
On to the next!

Turns out after a few days it broke again!

 

[SpareParts]

This lift gate is sure a PITA and I think I burned out the new drive gear clutch part.
That drive gear has a gear you need to remove to replace it. The gear itself is a soft metal.
The gear rides on a small shoulder on the drive gear shaft. From normal ware a grove will form on the gear allowing it to sit slightly lower on the shaft. When tightened down it will bind against the housing creating a lot of drag. You really can't tell it has more drag than it should as it's pretty difficult to override the clutch anyway.
So new gear on the way.

 

[SpareParts]

I was researching today and discovered the drive gear is ONLY for 07-09 from everything I can find. GM calls the system "Low Frequency Drive"
In 2010 the system was changed to a different style called a "High Frequency Drive"
Gm says the two styles are not interchangeable.
I was using a 07-09 drive gear with the 2010 module. It did work for a few days, then broke.
I think that is why I could not program the 2010 module with the 07 calibration and why the drive gear broke.

Incompatible parts. Lesson learned!

 

[SpareParts]

Remember how i was saying the rear lift gate will work intermittingly with the rear handle. Very frustrating as i could not figure out why.
I have been opening the glass and using a screwdriver to open the rear hatch when the gate would not function and usually im by my self so i just lived with it.
Yesterday i discovered that if the DR door is unlocked the lift gate will not open from the rear handle, as usual.
With all doors unlocked it works every time.
Don't know why it took me so long to figure that out but it did and i have never seen that posted anyplace.
Hope it helps someone else in the future.

Now i just need to figure out why when using the remote the gate unlocks, the motor turns but the gate does not lift. Drive gear is new and struts are new.

 

[Doubeleive]

Remember how i was saying the rear lift gate will work intermittingly with the rear handle. Very frustrating as i could not figure out why.
I have been opening the glass and using a screwdriver to open the rear hatch when the gate would not function and usually im by my self so i just lived with it.
Yesterday i discovered that if the DR door is unlocked the lift gate will not open from the rear handle, as usual.
With all doors unlocked it works every time.
Don't know why it took me so long to figure that out but it did and i have never seen that posted anyplace.
Hope it helps someone else in the future.

Now i just need to figure out why when using the remote the gate unlocks, the motor turns but the gate does not lift. Drive gear is new and struts are new.

I would have to guess if the motor is running and the gear is not working then there is a issue in there somewhere between the gear and motor, something is not engaging or something is not aligned correctly or something else is broken. if the gear on the motor is plastic maybe it cracks like the power mirror motors, when that happens the motor runs but the gear cannot because it lost it's grip.
I have not opened one up I recently grabbed a whole unit with the module out of a wrecker at the junkyard in case mine ever craps the bed.

 

[SpareParts]

The drive gear has to be engaged with the motor. There is no way it can not be.
The drive gear is new. The second actually and acting exactly like the first new one.
The drive gear acts like a clutch more or less.
For some reason the clutch does not seem to be engaging.
I could have gotten 2 bad new ones but unlikely although possible.

 

[Doubeleive]

The drive gear has to be engaged with the motor. There is no way it can not be.
The drive gear is new. The second actually and acting exactly like the first new one.
The drive gear acts like a clutch more or less.
For some reason the clutch does not seem to be engaging.
I could have gotten 2 bad new ones but unlikely although possible.

what is it that have replaced twice exactly? link?

 

[SpareParts]

Sure. Here ya go.

Amazon.com

 

[Doubeleive]

Sure. Here ya go.

Amazon.com

meh, for a few more bucks you can grab a whole used unit minus the module and call it a day, just be sure it's the same part I think there are a couple different ones depending on the year. if there are any at the local junkyard you can get it a lot cheaper I think i paid $30 for the one I pulled from a 2013 which will be the same for my 2012, I think 2007 is a different one
all you have to do is swap your existing module onto it.

Pardon Our Interruption...

 

[SpareParts]

Yes, 07-09 are the same. 2010 and up are different.

 

[Doubeleive]

Yes, 07-09 are the same. 2010 and up are different.

there is probably 4-5 of them in my local junkyard, they don't seem to be a high failure part so there usually still there even after everything else is tore down to the bone.
I only grabbed one to have on the shelf so I wouldn't have to pay scalping price for one or the module and it would be just my luck if mine failed that there wouldn't be one in the yard for months....