[QUOTE=swartlkk;496707]You need an encoder for an NV236, but really it isn't worth it to buy used. The potential for the used one to have the exact same issue costing you time & money is just too great.[/QUOTE

I agree here for sure. There some things I absolutely refuse to buy used & this is certainly one of them! I would definitely suspect that the encoder motor is of fault. The encoder motor can take too long to shift & it sends an error message to the TCCM, one too many codes & boom....no worky! Try this, unplug to reset the TCCM (my '99 Jimmy has it behind the kick panel on the passenger side) for 30 seconds, plug back in, if You now try 4 hi & it works (or @ least almost does & trying harder but,) it may engage a few times & then stop engaging, was the encoder motor/tranfer case motor on my truck! Hope this helps & do yourself a favor.....get NEW good quality items. Good luck.

 

I just had a similar problem. It's a '99 ZR2 blazer. Anyway, if you'd push one of the buttons the light would flash a few times, you could hear in the dash like area it trying to do something, and then the light would stop flashing and there'd be no engagement. I took it to a mechanic to find out what the problem was instead of me chasing the problem. He said it was the encoder motor. The first brand new one I bought was defective....it wouldn't do anything and I felt jipped bc at least the old one made an attempt to engage. So I returned the defective one and a few days later the other brand new one came in. I installed it last night and now everything is good to go. Hope this helps.

 

i have a 99 chevy blazer and when i go over a bump and or rail road track i can hear a clicking noise coming from the lower passenger side. long story short its the TCCM thats bad. well i never use 4x4 or will ever use it. so right now i dont have the $ to buy a new one & i just unplugged it. my question is will it mess up anything driving around like this ? djtyme209@gmail.com thanx

 

You will be fine. Would be sort of like unplugging your cruise control or disconnecting the headlights...you just lose the ability to do something, that's all.

 

One day the buttons stopped working I have been troubleshooting and reading the forum. So I have disconnected the computer module under the glove and cleaned up a little corrosion. The module has two plugs one very long orange with about 25 pins. The other black with 4 pins. I tested voltage on all and the only one with no signal is on the 4 pin, black wire ... connector labeled as "C". My fear is the cable that goes to the TCCM which means the TCCM is not registering power... likely dead... Any thoughts greatly appreciated. Also tested dash switch all pins getting voltage.
Any help greatly appreciated..

 

Fixed! Found a bad fuse ATC... funny thing is the fuse schematic under the fuse box cover did not show the ATC fuse. looked in manual and found the fuse.. The fuse blew because of corrosion in the TCCM.. All cleaned up working good.