ok well last week i was driving home and noticed my battery guage was a bit low then my radio started to turn on and off so i assumed my battery was going dead so i turned everything off and drove to the nearest auto parts store and shut it off tried to start it and sure enough the battery was dead. so i changed the battery every thing was fine and dandy then the next day same thing only this time the battery died alot faster and went compleatly dead to where the truck stopped. so called my dad and i swapped my battery for one of his in his f350 and drove to my shop and tested the volts while it was running 12v not 14 so i knew it was the alternator changed it and now the battery light is on all the time and the battery light was never on before when the batterys died but now that the battery and alt are new its on....i tried to clear any codes but it wasnt showing any

anyone know how to fix this?

 

Just a shot in the dark I assume you checked to see if the new alt is running correctly? If thats not it a fuse somewhere maybe?

 

Hmm, did you have the old alternator bench tested before replacement? Maybe you should take out the new one and get it bench tested. From afar, it sounds as if the alternator isn't being "turned on", and may be a wiring harness or fusible link related problem.

 

Sounds like it's an issue with the fusible link. Did you at any time short the positive lead to ground? That's all it would take to melt the link and cause your problem.

 

well im positive the old one wasnt working 12v while engine running and pretty damn sure the new one is working 14v while running

it may have been possible the main lead to the alt got grounded so this fuseable link how do i go about fixin that

 

I don't know for sure, as I am not a Ford tech, but my educated hunch is that the fusible link should be in the underhood electrical center. Ford usually places a map under the lid, or you may have to consult the owner's manual. The other possibility is that the fusible link is built into the wiring harness, but I think that's now antiquated technology (disclaimer: that's, again, my humble opinion based on general knowledge of vehicles). It's too late and I'm too lazy to go look at how mine is set up.

 

Is everything else operational?
I would check all connections make sure everything is nice and tight. Fusable link is just thinner wire meant to burn in two faster than the rest of the wire to protect from surges. You can buy them ay Autozone. You just have to find it. I cant help you there?

 

o so its just a inline fuse?

and yeah everything else works

ill go check things out

 

It depends. Most modern cars use a fusible link that plugs into the underhood fuse panel like any other fuse, circuit breaker, or relay. There's still a chance it's just a an inline piece of thinner wire usually encased in a plastic sheild.

 

ok there is a plastic inline fuse lookin thing on the main wire from the alt but no fuse in it....and i looked through the manual didnt find anything or even a fuse that it might have bee

 

Check for voltage at the front and back of that inline fuse.
Maybe you just need to unhook the batt for a few minutes and let everything reset?

 

that plastic housing is the fusible link, there are actually 2 of them in there, 1 to protect the electrical system from power surges from the alt, the other (most likely your problem) is there to "turn on" the alternator as said before, it gets a signal from the PCM i think.

 

ok ill check it out again now that its day time and can actually see

already tried unhooking the battery

 

Are you using a Ford or aftermarket alternator?

 

napa alt