I am not sure,my brother spent about 2 hours trying to find me and he is good at this stuff, he also suspected the alt. as last result,did something with one of the wires on it, then the truck would not die after turning off the switch, he checked my electrical wipers, radio, was surprised that he could not find it, I told him to stop as he already spent a lot of time on it,, to began with it I replace a cable that was in bad shape,ground I believe it was, thought this was the problem, then I checked the alt... it was bad, so I bought a new one, thought this was the cure,, took about 5 days and the batter was so bad that it would not take a charge,,not to bore you anymore, if you find out what it is, I may go back and look again,, this has been about 2 yrs ago..Fred