I changed the alternator within the last month after checking it out. It had gone bad. Everything was fine but recently I have been getting pulsing headlights and when I turn on the fan it pulses, plus the engine has started the same problem. This week I made a short trip and the van would not shift out of low. From one or two posts I have read it seems there may be a relation. I am going after the Y cable first. Any additional suggestions. 2006 2500 450k miles, Have an icarsoft2 reader but it seems to be a little sketchy. Possibly related due to voltage/electrical snafu. thanks, Skip