New owner of 2004 3500 Quad Cab 4x4 w/ Cummins and 4 spd auto. After setting cruise, it holds for about 2 seconds and then kicks out. Will not re-set until after next engine start. All other electrical works fine. Only had truck for two days and have not bought wiring diagram yet. Computer problem or perhaps as simple as a relay over-amping and not resetting until after restart?