all sorts of things could cause it.... have him take the door panels off both sides and make sure everything tightened properly if he comes across a lose wire or something re-soder it other than that if he has keyless entry or anything along those lines something could be wrong with that..but honestly it sounds like a lose wire to meThe locks are either locking or trying to lock again when he hits a bump. He has an '04 Sable. Anyone heard of this?