As I stated, with any vehicle, it is how it has been treated over it's life. I haven't owned a single new vehicle with the newest one being my Bonneville which I purchased with 24k miles on it. That car has had a few issues, but nothing that would make me want to get rid of it. I have probably spent $1k on my Bravada in misc repairs since I purchased it over 2 years ago and *crosses fingers* it is working amazingly well now. Even if I had to replace the transmission, I still wouldn't get rid of it because the trans decided to go...

What I'm saying is, you could treat your vehicle like it's some kind of god and you may still have problems with it not from your efforts, but rather based off of how someone else took care of it before it arrived in your care.

Now back to the problem at hand. The TCCM is located behind the kick panel in the front passenger footwell. Remove the kick panel and it'll be right there. I'd check over these connections at that point and see if anything looks corroded. If there ever was a windsheild leak, the water runs right down into that area and can lead to problems such as this.


Click on the thumbnail images for full size picture.

You may also want to check the grounds under the dash as well, however, these grounds support a lot more systems than just the TCCM.

 

Well I do agree with you about how it was treated before I owned it because it wasnt treated to well I guess.

Like he said ^^^ I would check the TCCM because that was my problems. I doubt its the vacuum lines but its worth checking out also. Check your fuses too.

 

From: 4 wheel hi light flashing but only rear wheels are working, Need Help
As I stated here and over in the thread linked to above, By disconnecting the battery, you are only resetting the TCCM which will return you to 2hi. You haven't fixed the problem, only gotten yourself out of the bind that you were in being stuck in 4lo. From there you need to check over the wiring throughout the system, both at the TCCM and all of the wiring at the transfercase as well.

If everything looks good there, then you mostlikely have a problem with one or more of the components in the system. Further diagnosis really requires the use of a tech2 or equivalent scan tool as the TCCM will have a code that should indicate the problematic component.

*Moving to General Tech Help for more exposure*