I have a 1996 Chevy Suburban K2500 7.4L 454 4X4 with 217000 miles. Originally, driving the truck to about 40 mph would appear to slip into neutral, while the speedometer kept climbing. Stepping on the gas made the speedo go faster, but the truck did not. Once you slowed down to about 20mph, it would make a very disturbing sound like it was slamming back into gear, and you could accelerate again. At first, you could engage 4WD and it would drive up to 70mph without slipping at all. It has deteriorated to a point that driving in 4WD does the same thing now. I didn't think it was the transmission, because it drove fine in 4WD for a long time, so I suspected the transfer case. I have inspected the transfer case, and the chain and gears seem to be in good condition. I was told it could be the TCCM or the transfer case mode fork or pads. The pads are a little worn and chipped, but is that sufficient wear to cause it to act like this? What is the function of the TCCM in this process? Where is the TCCM located? I was told in the door panel, and under the steering column, but haven't really located it yet.
What further steps can I take to troubleshoot this effectively?
Wednesday, October 12th, 2011 AT 4:45 PM