service 4X4 light

My 99 Jimmy has the 4 button 236 transfer case system and the service light would ocassionaly come on but now its stays on and none of the selector switch lights for 2 wheel or other come on at all. Nothing happens when I try to engage. I've checked my vacuum hoses and disconnected the tccm to check for corrosion on the terminals but it looks good. I took the dash switch out and opened it and the solder connections look fine but I guess it could have a bad diode too. I see that you ask about codes and can I retrieve the codes or does mine need a scanner ? Can Autozone scan it or what kind of scanner does it take ? I've been thinking of buying a scanner, is there one I can get from accutron or equs ?

1 other thing I just remembered was last winter when I had it in 4 wheel high the light stayed on indicating it was engaged but it had actually kicked out of engagement so I switched it back to 2 wheel then back into 4 wheel and it worked again ? thanks

You need a good high dollar engine/transmission/transfer case capable scanner to test it and get codes.
Most good repair shops cand test and get codes.
Post back any code no.

Has transfer case ever been serviced with the GM blue transfer case fluid?
How many miles on it?

Any check engine or abs brake lights?

It was the TCCM or chassis control module THANKS

You are welcome.
Mind telling us how you figured it out?
It may help others with sme problem.

I didn't have access to a scanner but I came to the conclusion-guessed it had to be the module after I read many different posts and the majority of them were module related. I knew I had vacuum which seemed to be another main cause of problems. and when my system was last working (it started as a occassional problem) the dash switches worked properly so I had doubt it could be the switch. The dealer charges $ 85 just to hook up to their scanner so when I found a used module for $ 75 it was worth the gamble to me. I actually needed a couple other items (grill & inner bumper) at the junk yard so I talked them into $120 instead of $145 for all three items. GOOD DEAL !!! Now I'm taking out the blend motor to try and fix that problem. GRRRR

Thanks for letting us know.
Sounds like you come out good on the price of parts.
That takes a lot of hurt out of the repair.

Good luck with the blend motor.
If you need help on it.
There may be a how to in the S-10 how to section.
Or post back.