I have an 05 F150. Just recently my battery light came on. Everything is still working fine. The gauge even shows the battery is properly charged. Any suggestions on what is causing light to come on?

 

If you're going by the dash gauge, it's pretty pathetic. I'd see what the voltage is across the battery terminals with the engine running. If the charging system is good, you should see something in the 14V range. And if that is the case, then I don't have a clue why your battery light is on. However, if the voltage is down in the 12V range, your charging circuit (probably alternator) is bad.

- Jack

 

X2 on the dash guage. If your battery light is on, then there is a charge on your battery. I could be that the alternator is charging, just not enough to to supply the electrical load needed to operate the vehicle (that is generally a bad voltage regulator, but it doen't matter becasue the alternators in these trucks have internal voltage regulators, so to get a new one, you just get a new alternator too).

There is another thread on the same basic thing right, now, might want to check that one our too.

 

Guys, you were both right. Truck died the next day after I posted the original thread. DEAD alternator. Went to auto zone and bought a rebuilt one for $199. Put it one and noticed a whistling sound. Now I have to take that one off and return it.

 

They wont take it back if it has been installed, least that has been my expirence.

 

I think he is saying it is defective. Surely there is a warranty and they will take back a defective one that has been installed. How else would you know it's bad?

 

True, true, for some reason I read his post and then my brain decided to let my think it wasn't the alternator that was the problem........

 

I've never done that. No, really, at least I don't remember doing it.

 

Make sure to charge your battery before installing the new alternator. The alternator is not designed to charge a dead battery and there is a good chance of frying the new alternator trying to do so.