My '96 5.0 4sp auto has been running really great but recently I had hell when the engine kept shutting off while driving. I realized it was when I had the headlights turned on. So I had the alternator checked...bad diode. So 1 new alternator later, still similar problem, just not as common, but just as hard to diagnose. Any ideas why it would do this?

 

Check the light harness for any shorts? Do you have daytime lights?

 

Your headlight switch probably has a short in it. I don't know if ford only did this in 96, but if your headlight switch shorts out, it kills the fuel pump. Don't believe me, disconnect the headlight switch and try to start it. My truck is a 96 to.

 

I think you disconnected the tank selector switch while screwing with the headlights.

 

My truck doesn't have one. It's a single tank.

 

Its a bad ground. Clean the grounds off the battery and check for continuity on them too.

 

Thanks. I figured it was something like a short in the wiring but I just wasn't sure.

 

there is still a plug that a harness plugs into where the selector switch would normally be. At least on my 92 it's like that.

Found out when i was in a rush what it was that plugged in. Left dash off since i had to replace some bulbs the next day, found out when i needed to get somewhere that that harness has to plug in