jchubb01

My alternator is fixed!! Here was my problem and to help eveyone that has this. (1997 f150 xl 4.2l) The voltage exciter fuse was burnt, replaced that along with the bad altenator..... So... After I pretty much replaced everything... It still wouldnt work... I found out that the fuse on the firewall, the 175amp fuse that connects the altenator to the battery was burnt out... Now mind you, when I tried to see if the alternator was putting out any voltage, It wasn't. Very strange. So I went to work and got a call from my father and he tells me that fuse (the 175amp fuse on the firewall) was burnt up. He replaced it and it was all good after that... Apparently when that fuse goes out, the voltage exciter fuse doesn't get any power, therfore it doesn't "turn on" the alternator.

So there is some food for thought when diagnosing alternator problems with the 4.2l engine.

2002FX4

aka the megafuse