[PaulHilgeman]

Ok, got some data here.

I was able to get the '2HI' and the '4WD Auto' lights to light. When I press either of the '4HI' or '4LO' buttons I get some clicking from the TCCM, and the '2HI' light flashes, and it never changes over.

The 'Check 4WD' or 'Service 4WD' light is always lit.

The TCCM model is 15154323.

I checked all of the fuses and they were fine.

I disconnected the battery for 2 hours to reset anything that may have needed it. The 'Check 4WD' light turned off until about 2-3 minutes after the car was started.

The good news is that the rear differential seemes to have unlocked through this process, so the car drives MUCH smoother when the '2HI' light is lit. When the '4WD Auto' button is pressed and the light is lit, it corners a bit rougher when doing sharp parking lot style turns.

Any idea on what I should do next?

I will go back outside and re-install the TCCM to see if simply unseating and reseating the connectors does anything.

Thanks a ton guys!