Hi all. I have a 2000 Expy with 126,000 miles on it. I was pulling into a parking space this morning. Slowly, on concrete, 75 degrees, dry, etc. (no way the rear wheels could have slipped) The 4x4 light came on and I could immediately tell the 4x4 had actually turned on. After stopping and restarting the truck, all was back to normal. What the heck happened? Thanks!!!

 

Yeah, same thing happened to me, I couldn't figure it out! 2001 XLT, 109000.

Just pulled out of a parking spot, and was just kind of creeping along (2-3 mph) when all of a sudden I could hear the sound of the drivetrain change, then I noticed the 4WD light was on. So I stopped, moved the switch from A4WD to 4WD, drove forward a bit and then stopped again and switched it back to A4WD, and it switched back the way it was supposed to be.

That was about a month ago, hasn't happened since.

 

I know my rear clutches are starting to slip also. How is your rear-end Holo20? (nothing personal). The best way to feel the slip is to turn a corner from a dead stop while accelerating - you'll feel a vibrating. Does anyone know if the sensor for sensing rear wheel slippage is in the axle? Could this be causing it to think the rear wheel is slipping? Just a thought...

 

Well, now that you mention it, whenever I make a turn from say, a stop sign, there is an obvious "thrum thrum" sound that resonates throughout the vehicle, until it is almost straight again.

Do you know what all is involved in fixing it?

 

IF your rear clutches are slipping, it is pricey ($700 @ dealer??) to have them rebuilt. I'm putting mine off until it gets real bad. In the meantime, you can add some (few ounces) friction modifier to the rear end. This may help.