'07 Yukon XL Denali rear door unlock

[BSarteSr]

Sure it's probably your VASS module!

Sorry just kidding I have no idea what/where the VASS is.. but it's in the wiring diagrams that nobody can understand! And it does connect to your doorlocks..
View attachment 398365
See you have the Lock/Unlock relay and the Unlock relay.. makes perfect sense right?
Looks like tan and grey wires to the motor.. something must flip polarity or something something..
headhurts.. naptime..

About the relay you found..it maybe your signal flasher.
Keep us posted, would like to have an idea how the doorlocks work!

Any chance you have this for the 4 door vehicles?

 

[mikez71]

Hi BSarte, that diagram is for the 4 door vehicles. The diagram is for the rear doors.

I am guessing VASS is just an acronym for the system like 'stabilitrac' which is integrated through the ecm, brake module, steering/yaw/wheel sensors etc.

Main thing is the locks use the same wiring for lock and unlock and for both doors. And if the relay can be heard clicking, then the relay is getting the signal from the BCM.. so it seems to me like the relay switch contact maybe bad.

Just think, your locks could have lasted twice as long without the auto-doorlocks!

I wonder if its possible for the lock motor to fail partially shorted.. not enough to blow a fuse, but put extra current through the relay and arc the switch contact. Speculation, but searching the web, there can be partial motor shorts.

So if one of my doorlocks quit working (and it should quit working for both lock AND unlock) I am going to try and not use the power doorlocks until the bad one is replaced.. wouldn't matter if motor is not shorted, but just in case.

I am curious what the PCB looks like in the fuse panel.. hopefully the relays can be replaced with some soldering

 

[dustyb]

Hi BSarte, that diagram is for the 4 door vehicles. The diagram is for the rear doors.

I am guessing VASS is just an acronym for the system like 'stabilitrac' which is integrated through the ecm, brake module, steering/yaw/wheel sensors etc.

Main thing is the locks use the same wiring for lock and unlock and for both doors. And if the relay can be heard clicking, then the relay is getting the signal from the BCM.. so it seems to me like the relay switch contact maybe bad.

Just think, your locks could have lasted twice as long without the auto-doorlocks!

I wonder if its possible for the lock motor to fail partially shorted.. not enough to blow a fuse, but put extra current through the relay and arc the switch contact. Speculation, but searching the web, there can be partial motor shorts.

So if one of my doorlocks quit working (and it should quit working for both lock AND unlock) I am going to try and not use the power doorlocks until the bad one is replaced.. wouldn't matter if motor is not shorted, but just in case.

I am curious what the PCB looks like in the fuse panel.. hopefully the relays can be replaced with some soldering

I've kinda of speculated that it was the instrument block with the built-in relays. It's $80 from gmpartsdirect.

I've also speculated that one door actuator is bad, so it's drawing too much current causing both to fail. I believe unlocking takes a little more effort from the actuator, so that's why that fails to engage. 100% just guessing here.

I think I'm going to try unplugging both door lock actuators, plugging in new ones(without going through the effort of installing them) and see if that that does anything. If it doesn't, I'm going to try replacing the instrument panel fuse/junction block.

I'll post back with my results as soon as I get the stuff and test it out.

 

[Mean_Green]

Not familiar with this year vehicle, but most lock actuators are simple solenoids or DC motors. 12V to one wire locks, 12V to the other wire (reverse polarity) unlocks. (Pulls solenoid vs. pushes solenoid if you will)

Not digging into the wiring diagram, is there a common scheme for the two rear passenger doors that is somehow different from the two front doors? Is there a common point or component?

Have you had the doors apart enough to get to the connectors? If so, can you put a meter on them and see if the voltage is reversing polarity? Can you apply 12V direct to the actuators without any of the vehicle buttons or controls involved? That will test them to see if they're good or bad. Would/could both fail? Well, on my '95 Taurus all four power window motors failed within about a week of each other. I had to replace them all.

Now, all of that assumes this system uses simple power principles and is not computer controlled somehow on you newer than mine vehicle.