I currently replaced the alt. and when I tried to start it, didn't start. I jump started and it turned on. Then when I took the cables off the truck would stay on for about 30 sec. and then shut down. I jumped it again and started and the same thing happened. What can it be?
Ok first of all never unhook the battery with the engine running, on today's vehicles, you can cause a voltage spike and fry electrical systems. A customer of mine did that on his Ford Crown Vic and after it was all fixed and running the total repair was 1800 bucks. So that being said, get the battery recharged and tested then start looking for a fried main fuse in the power distribution box, if nothing is found there then check the wiring for the alternator, it is possible that one is broken and that will not allow the alternator to energize. This of course is assuming that the alternator is good and not allowing a feedback through thus killing the battery. Hopefully there is no damage caused by the battery disconnect.
Question tennisshoes: When you speak of unhooking the battery while the engine running, do you mean the assisting vehicle or the vehicle being jumped?
Search Ford F-150 Questions
Ford F-150 Experts