Yesterday I put my truck in 4x4 sitting still in drive. When the dash showed the truck in 4x4 high I started to let the truck roll forward at idle. PING with a loud engage sound under the hood. After I cleaned my pants I tried it again this time it went in and out fine. Is this something I need to worry about. first 4wd. Do you have to shift to neutral? Manual said it was fine to do it as long as you did not shift to low.