I can not figure out why after replacing the dash contro; switch 3 times on my blazer i still have no 2wd light, no 4 HI Light, No 4 Low Light, No neutral light, NO Automatic 4 wheel lights. No matter what i do they do nothing. CHecked all fuses and checked out ok. Ran test lights on power wires and they are hot. All plugs are plugged in. Nothing is damaged under neath or melted into exhaust. Only has 154.000 miles hi way only. Bugging me big time. Any help is greatly apresiacted as Captain Chuck knows first hand. I ran codes and they read that OBD2 lost all commacation with NV236 transfer case.

 

Check the pins in the TCCM connector, and on the TCCM, for corrosion, (fairly common problem). The TCCM is located behind the passenger side kick panel.

On the TCCM connector, pin C9 is a dark green with white stripe wire.
In the data link connector there is a purple wire in pin #2.
Disconnect the TCCM and measure resistance on the dark green white stripe wire to the purple wire. Must be less than 5 ohms. If it shows open, look for an open circuit in the dark green white stripe wire starting at the TCCM. It goes to a splice pack with a few other wires and connects to the purple wire. That is the serial data line.