So I have a 96 F250, 136,030.6 miles on it, XL. I just did a oil change today that how I know it so well. I was having a problem with my battery light coming on the off a few months ago. I couldn't figure the problem out then, checked the altonter, batteries, cables. When I load test the batterys they where low. So I knew replacing them was soon but at the time money was not there. I replace them about 1.5 months ago when they quit on me. That stoped my battery light on dash problem. It when away after that! So I just figured it was batterys. Well today it was back on and now on when the truck is running. I know the start is going bad and cranks slow. Battery load test good! Figured the old batterys killed the starter. So I picked up a new one and it going in tomorrow along with a new start relay. Old one looks stock and for 22 bucks It can get a new one. I tryed to test the altonator to see how many volts it putting out but my voltage meter meet the fan blades before I could test it.

What could be causing the light to come on? Anything I should check while working on it? Any help would be great! I will get a new volt meter tomorrow. Also would that throw a code the code reader at work will pick up?

 

Sounds like the alternator has a bad diode in it. Replace the alternator.

 

Check the connector on the top of the alternator. The socket and pins are known to get loose. The wires almost always get flattened from laying on them while working in the engine bay.

 

There is a rubber hose that lays across the plugs on the ALT that causes this problem. Bend the metal loop bracket it's in back so it doesnt lay on it. The hose vibrates the plugs and causes the light. Well it did on mine anyway

 

Check the main wire on the back of the alternator. The ring connector on my broke a few months ago and needed to be replaced. It was still charge when it was touching but it was barely held on by the little rubber boot.

 

Mine is starting the flashing battery light again as it has twice in the past. Both times I replaced the alternator and it fixed it. Now I need another one, Advance Auto is going to get tired of me getting a free replacement all the time. When I pull my camper I use a invertor to run two small refrigerators while driving down the road. My alternator really gets a work out and that is the reason they keep wearing out. If I replace the alternator again and the light keeps flashing well then, I might have one of the problems listed above.

 

I dove around 50 miles yesturday and had no problem with it. Restarted fine, so i'm thinking it the problem described up top. Will check in a little.

 

my truck has a similar battery light issue- it was intermittent for a while and now steady since the colder weather has set in (she likes it about as well as i do). new batteries, starter, and fender solenoid within the past several months, and alternator tests good. my boyfriend, a certified tech, was wondering about a voltage regulator??

i need top off power steering fluid and change a light bulb tomorrow, so i guess i'll add checking above-mentioned alternator items to the list lol...she starts strong and runs fine, so i'm not too worried, it's just annoying to see the light

 

Don't forget it could be the regulator. Mine was flashing intermittently for a while. I replaced the regulator and it has been fine ever since. I noticed when the light came on, the voltage gauge would jump slightly, I also noticed the batteries were boiling over.

 

The battery light is always the alternator , or the connector on top of it ...The regulator is in the alternator ....

 

The regulator is on the back of the alternator and it can be replaced separately. It was making my light come ON on the dash when it would randomly quit working.

 

Cool ...

How do you test which one is the problem ?

The light on , it is still the alternator , whether it is the alternator windings , or the regulator ....
That was my point ....

 

Mine is doing it as I said but I thought I would throw in that I put my scan guage on volts and I'm always showing 14 +or-??

 

Glenn ,did you check the connector?..

 

Voltage regulator wether internal or external to the alternator is replaceable. Its all in how much work do you want to do.