1999 Blazer 4WD problems

[BlownM3]

First let me say that I did read the new write up on non working 4WD. So the service 4WD light came on and it was stuck in AUTO 4WD. I would punch the buttons on the 4 button mode selector switch but nothing would happen, not even blinking lights by the buttons. I replaced the mode selector switch with a brand new unit, didn't change anything. Finally I reset the TCCM by removing the neg battery cable. This worked and it returned to 2HI. The service light came back on. How do I trouble shoot what the problem is? I have heard about the harness getting messed up by battery acid by the battery tray. Also heard about replacing the TCCM and encoder. I also heard about accessing the transfer case trouble codes by jumping pin 13 of the OBD2 connector to ground but mine has no wire landed on pin 13. I think a code scanner is needed for 1999 and up vechiles with the automatic transfer case. Thanks

[OverBoardProject]

Welcome to Automotive Forums

If possible how about running to Autozone and get the codes read for free. Then we'll do our best to help you out.

[muddog321]

So, the question is does it work now? If so you are done - TCCM got a bad input and I think Microsoft designed the software so the reboot fixed - usually. If it still hangs or light flashes step thru the tests/fixes yourself or take to the dealer. Remember "Auto" only uses 2HI so look at the front stuff and vac lines.

[BlownM3]

Originally Posted by muddog321

So, the question is does it work now? If so you are done - TCCM got a bad input and I think Microsoft designed the software so the reboot fixed - usually. If it still hangs or light flashes step thru the tests/fixes yourself or take to the dealer. Remember "Auto" only uses 2HI so look at the front stuff and vac lines.

Well the button was stuck on auto and it was in 4hi. I know because it was binding up while turning in the parking lot. I will try to see if the problem is fixed. So sometimes does the "reboot" fix the problem? I was just worried about pushing the buttons and recreating the problem. I guess worse case I will just have to reset the system again. I don't think the scanner at Autozone will work for the transfer case codes. I just returned a loaner OBD2 reader to autozone yesterday for my other car, should have waited I guess.