I'm not sure where I posted this (Montana or Venture forum), but I had a similar problem with my 2003 Montana. On mine, it was covered by the 3yr/36K warranty.
The right rear ABS speed sensor was bad (not sure of the fault mode), and because it an integral part of the bearing hub unit, the whole thing was replaced.
The symptoms were that first thing in the morning when I would start the car (usually on a cold morning), the lights would come on (Traction/ABS/Service Traction) and the traction control would be deactivated. If I pulled out of the garage, shut it off and restarted the car, the lights would go out.
You might first check to make sure that the electrical connection to the ABS sensors at each wheel are not corroded. If they look okay, you'll want to have the codes pulled from the computer. They might be proprietary codes, so your local Autozone may not be able to read them......good luck, Glen