I have a 2003 F-150 5.4L, in the past couple months I've been having issues with my battery light coming on and then going off.

I changed my alternator about two months ago, seemed to fix the issue but only for about 3 weeks, I then had the battery light come on again but soon turned off.

Up until yesterday the battery light did not come on again until last night it came back on. Drove for about a 35min then parked at home for the night, In the morning started the truck back up the light was still on and did not go out. Left work tonight, drove for about 10min then the light went out but only for about 2 min.

So my battery light is still on now.

I tested the the battery while the truck was off, I was getting my 12 volts

Started the truck, battery light still on, looked at the volts on my meter and I was getting a good 14 volts.

So it looks like it's charging???

Any ideas.. Where should I go from here...

Thanks!

 

Just a shot in the dark here, but you might have a defective alternator...was it a re-built ?? Warranty ?? It could show 14 volts, but if the amperage is low it could trigger the light. How old is the Battery ? it should show 12.5 with no load or so if good. Also check ALL grounds and wiring for good contact.

 

2x above. Also take new alt back to place bought from and have them check it. Take old one too while your at it see what it says on test bench.

 

If its a 7700 series as in the HD work truck kind make sure you get the right alt too.

 

update from this am,

Just off the battery - 12.15v
Truck Running - 14.50v, 14.53v
Everything Runnning / Load - 14.5v, 14.6v

Battery light turned off and back on a couple times this am. Now it's staying off.

We recently got a boat load of rain, could this be having an effect on it? Like the grounds getting wet etc...?

How many grounds would I find on my truck thanks again!

 

It's a re-build as far as I know, probably still have warranty on it.

The battery is about 5-6 years old, Optima red top.....

 

It is the right alt...