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HELP! Transfer Case? Four wheel drive? service 4wd code, randomly goes into 4wd

pahusfelt

New Member
Joined
Nov 19, 2019
Messages
3
Ok, I have questions and I am having difficulty finding the answers. So, I decided to come here and pray someone knows something more then I do.  First - I bought my 2003 Avy (1500) approximately 2 months ago. It had high mileage, but looks brand new, ran so very smooth, quiet, and as if it were a steal at $1,800.  I replaced the brake lines from front to back because they were rusted. Put 2 new tires on it, and BOOM - I was tagged.  The truck is not used every day, but it is driven 3-4 times a week.  While driving - there was a sound coming from the drivers side- underneath - almost sounded like something was loose and flapping in the wind - but I couldn't determine what. I drove the truck on a 2 hour trip down and 2 hour trip back. Drove like a charm.  The next day, I drove it about a mile away, my transfer case went out.  My father was knowledge enough to be able to tell me it was the transfer case. The transfer case had absolutely ZERO fluid in it - which was that rattling sound I had heard!  I replaced it with a used transfer case.  Drove it about 3 times and the "service 4wd" code popped up.  After the truck sat over night - the light was gone. Drove it a couple more times.  The last time I drove it about 15 miles and it randomly put itself into 4wd.  I put it back in 2wd and drove the 15 miles home.  Now it has a red light on next to the 2wd and the service 4wd is coming on randomly.  Anyone have ANY idea what I should check? What could be happening?  Why my indicator light turned from blue to red?  ANY help or information would be GREATLY appreciated. 
 
Im having the same problem with my 03 as well. I have checked wiring and replaced the encoder motor and checked the fuses as well as changed the buttons. I used to have the dash lights on the four buttons on when the truck was on or running, but now it is completely dark. Im actually thinking about just manually shifting the tcase to 4 hi and then wiring the front dif to a switch separate from gm's wiring. everyone says these systems are reliable, but im not convinced. ive had mine for almost two years now and the 4wd worked a handful of times when i first got it. I got it with 92,000 miles and it has 120,000 now. ive also replaced the transmission at 98,000. 4th gear went out, then third. If you find out how to fix this issue, please let me know. all the advise i hear on the internet and from youtube, doesn't solve the issue for my truck. 
 
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