I have a 1994 Ford F-150 with a 5.8 liter engine, automatic. My problems started with a dead battery. I bought a new heavy duty battery and then discovered that the alternator wasn't charging. I put in a new alternator And discovered although it showed it was charging the new battery still ran down. In my Haynes book it said to check for shorts by removing the negative cable qnd placing a test light between the cable and the battery post. The light lit up indicating a short. I disconnected the alternator harness and the light still stayed on. The Haynes book said to then pull fuseses one by one to find the short. I did that but nothing put out the light. I even pulled the fuses under the hood in that fuse box to no avail. I need this truck for school and for the life of me can't find this short. Can anyone suggest other tests? Thanks

 

Sounds like you're on the right path - perhaps get a bit more radical - pull all the fuses out at the same time, then if the light goes out, plug them in one-by-one until the light comes on.

If the light doesn't go out, at least that narrows things down to the larger lead wires. May have an issue where the wire insulation has rubbed off somewhere??

Not a pretty job - pretty much divide-and-conquer in a methodical manner.

 

I had a 93 Dodge Dakota that was doing the same thing. The battery was dying while I was at work and overnight. It would start with a jump and run fine all day, so long as I didn't leave it sit too long. I replaced the alternator because a mechanic tested the circuit and said it was faulty. The problem still continued, however.

Turns out the voltage regulator was faulty and was causing the alternator to draw power from the battery when the truck was turned off. $10 and a free install from the mechanic and all was fixed.

 

Another thing I'm wondering. Ford sent me a letter about a recall concerning the cruise control, could that be an issue with this?

 

This models alternator has a built in regulator and since I just replaced it the regulator should be good.

 

for some reason the short dissappeared im not sure what i did.... However mechanically it is running bad now: sputtering while in drive idling, hesitation (im not sure if this will help but i thought i would through it out there for any one who is looking at this post)