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The involved fuse may be the transfer case control module fuse (TCCM). This fuse is in the underhood fuse block and is labeled ATCM or TREC.
If this fuse is good, remove it for 30 seconds and then re-install it. This may wake up the AWD module and cause it to work again. If that is the case, any GM dealer can upgrade the software in the TCCM which should prevent this from happening again.
If this doesn't wake up the module, let me know and we can continue.
I should have specified engine off/key off.
It's better to do things which interrupt power with the key off. Also, some devices can get power from a second source when the key is on.
Yes. They are really good at having 12 different terms for the same thing.
There are a couple ways we can go with this now. The best thing that would help diagnose this would be to have it scanned for chassis codes. I'm not sure how I can advise you best to go about getting that though. Many parts stores offer to "scan" vehicles for codes, but they often cannot access chassis codes, only powertrain codes.
Another thing you could do is to check the fluid and see what it looks like. If it's really low, or really burned, then there is likely an internal problem.
It's either electrical, or mechanical. So we really need to know if there's a chassis code.
That is the fuse for the module, so if it was going to work, that should have done it.
How many miles are on the vehicle?
Did it work fine recently? or has it not worked all winter?
One last question. The last time this happened, did you take it to a GM dealership, or an aftermarket facility?
The site acts up from time to time, but it's harmless.
Ok, I only wondered about the dealer because there are a lot of bulletins pertaining to new software for the awd module. The most recent revision seems to be around 2006.
If the last visit was under warranty, I might be able to see what was done by entering the VIN#. If it wasn't under warranty, it would be important to know if the module was programmed.
If you'd like me to check the VIN, I could do that. It would also allow me to see what the latest software revision is, so you could compare to the repair date.
This is alll I show for repair history, so anything after 2004 isn't there. I put the VIN in to see what the latest calibration is, but there are a bunch of part numbers for the modules, so I cannot determine.
I think that if the parts store isn't too inconvenient, it would be worth a try. Just make sure they know to look for chassis codes in the transfer case module.
You don't need to accept until you're ready. If you do accept, I will keep the question open until I'm sure that you don't need anything else.