I have a 2007 silverado and am having a problem with the 4wd. For quite awhile the 4x4 would just stop working then i would let it sit for awhile and then it would be all good again. Recently the problem is that the selector switch would indicate 4lo but it would not be in 4wd. Would shift like it was in 4lo but no power to front wheels. I have changed selector switch and cleaned the ground under drivers side with no luck. Brought new TCCM and now the lights on the selector switch wont come on and code u0102 comes on which is unable to communicate with tccm. Truck I believe has defaulted to 2wd cause shifting is now normal. Have read on here about the actuator and encoder motor but wondering how I could text these parts before I buy new ones. If I put the old TCCM back in the 4lo light comes on but trusck is still in 2wd. service 4wd warning comes on all the time.