4x4 switching by its self

vehicle switches into 4x4 on its own on start up. From 2Hi to 4Lo or 4Hi.No one can seem to help me.Have asked several dealers and no one seems to know.Can any one help me?

The problem might be with the transfer case control module. The dealer should be able to connect a scanner to determine if this is the problem. The module is located behind the right side kick panel. Or, you could get a replacement module from a local auto recycler and see if that fixes the problem.


I have a 2000 Blazer 4x4. According to a GM tech, if the truck is not put into 4wd occasionally the TCCM will lock up. In my case it kept me from switching into 4wd. He suggested disconnecting the TCCM to reset it. Rather than remove the kick panel, just disconnect the battery for a few minutes. Due to its location, the TCCM contacts get corroded and may need a cleaning.

Ed B.