Just a follow up message....Back in October, 2010, (I posted messages) I replaced my encoder sensor and the "service 4wd" message was still showing up baffling me. About 2 weeks later I replaced the windshield washer tank. I had to remove the battery to do this. I was taking my time as I was in no hurry. The battery was out of the vehicle for a good 2 1/2 to 3 hours. It is now January 12th and I have not seen the "service 4wd" message appear and I have been constantly shifting the 4-wheel drive as it can't seem to quit snowing here in South Dakota. Just wondering, (knock on wood), any chance the on board computer reset itself???