I'm having a problem with the 4 wheel drive on a 1994 GMC Jimmy (S-10 Style).

Uh....stay out of the mud?

Darryl, do you know if you have the NV236 t-case in that thing? There are two fuses that power/protect that system. You could have one good one that would power up the indicator lights when you first turn the key on, and one that is blown, causing the no engagement.
I don't have t-case wiring diagrams for a '94 here at home...what I have here only goes back to '98. If you want, P/M me with your VIN #, and I'll get the diagram tomorrow, and send it to you.
I see a lot of issues with the wiring harness on these, too. It seems to have a spot on the driver side, at the top of the bellhousing, that wears thru the insulation. Might check all of the fuses(under dash & under hood) first. I do see some select switches take a dump...

When you put it in neutral, and go to 4 low, does it shift then? I have a 94 Blazer S10. Dang shifter motor went out on mine. Not Cheap.

Joel, it has the NV 233 C transfer case. I checked the fuses under the dash and they all checked out good. I don't see any under the hood as on the newer models. Maybe the selector switch is bad. Power is coming in but not going out. Is there a relay in the system?

Schematic does not show a relay in the system. I do have the troubleshooting charts, and the electrical diagram. I will send it to ya via e-mail, once I get it loaded.
If you have checked, and there is 12v at the switch, but only on one terminal, and not on any others when you press the button, it could simply be the switch. It's fairly easy to replace, and not very expensive...might be worth a shot. I've replaced quite a few of them for this very reason...

Thanks Joel,

Joel,  Thanks for sending me those troubleshooting charts and schematics. They are a big help. As of today after numerous voltage and continuity checks, everything seems to be pointing towards the TCCM. That's the expensive one. $240 my cost from the dealer. Yikes!  So, tomorrow I guess I will be scouring some of the local salvage yards.

Well, I got a TCCM at the local salvage yard. And I almost go killed there too. Idiot driving one of those huge forklifts that they use to load junk cars into the crusher....he didn't see me in the vehicle next to the one he was trying to get the forks under. Nothing like seeing and feeling this old Ford F150 being smashed up against the side of the vehicle I was in til the operator got his forks under the vehicle. Glass was a flying, the forks came through the door. It made for an interesting morning.

I know what ya mean about the crusher personnel! I used to work at a wrecking yard(ooops...Salvage yard...gotta be PC ) I loved it when the crush crew came thru every year!! Never a dull moment with them guys!!!

Glad to hear ya got it fixed, without getting mashed!
Those mode motors ain't much more than 'lectric window motors...not really meant to be used in the harsh environment of the underside of a 4x4. A little water/mud, exhaust heat, and non-use will create problems on most of them.