The likely problem is the vacuum switch has a leak in it and when the vacuum rises it activates the front axle interlock. When you shift it the valve gets moved and the vacuum bleeds off and then the problem starts over.
Pull the vacuum line off of the actuator (under the battery) Or follow it up to the nearest connection and disconnect it. Plug the line on the engine side so no vacuum can get to the actuator. See if it still does it.
The actual valve is about 20 dollars and isn't real hard to change.
Tuesday, July 1st, 2008 AT 9:57 PM