surprise, i got another issue with my 99 Bravada. we have been experiencing below freezing temps, last week it was 4* and im ashamed to say i really dont warm up my engine before i drive i just idle it about 20-30 seconds then drive off, well as soon as i take off i hear a couple clicks from the TCCM then the "service AWD" light comes on. the car will still drive normal and usually when i get to my destination i disconnect the battery for 5 minutes and everything is fine again. this happened to me 3 times in a 2 month time.

i just changed the transfer case fluid with Auto Trak II so ill see what happens and all fluids are regularly checked and topped off as needed. but is this an electrical problem? i dont have the scanner to pull codes from the TCCM i know it would be nice but i dont. anybody have any speculations?

 

i probably should mention the AWD does work great when the light is off. when the roads are snowy i stomp on the gas pedal to get the back wheels to slip and the vehicle quickly reacts and moves.

i have not tried it when the AWD light is on

 

Could be any one, or more, of countless things. When it acts up, and the light is on, do not turn the ignition off. You need to have the DTC's, (Diagnostic Trouble Codes) retrieved. To retrieve them, you will need a scan tool capable of accessing the BCM, (Body Control Module). The el cheapo scan tools at the auto parts stores are not capable, so you'll need to stop at a repair shop. Typically the BCM will store a DTC, but in this case, the TCCM might be losing voltage, in which case, it may or may not store a DTC.

 

ya i kinda figured i would need to find a way to get the codes im not gonna spend the mucha bucks to get the scanner to solve this issue so ill have to find somebody that can do it. i know you said dont pull battery, but the last time i did that was when i changed the Autotrak II fluid in transfer case and i have not seen the light since but next time it comes on ill take her to my mechanic who can pull the code and report back

 

I would just check with the shop to make sure they can pull those codes, not just any shop can. The shop that works for my dad's business can pull those and they usually don't charge much.

 

ok im checking around at some places including the local GM dealer. my mechanic says he does not have a scanner to access the TCCM

its been about a week since i changed the fluid in the transfer case and i have not gotten the "service AWD" light yet but when i do ill leave it so i can get the codes

 

Hopefully changing the fluid was all it took.

 

ya so far still no light over a month later