Intermittent dashboard Battery Light

[spmiller]

Driving home on the highway last night, got an intermittent battery light on the dash. Not on solid, kind of half way, sometimes went away. Headlights were very weak.

When I got home I put a voltmeter on the battery with the engine off, read a little under 12v. Then started engine, and read just a little over 11 volts. If the alternator is fully working, shouldn't it read about 14V?

Anyhow, trying to figure out what went bad. I also see on the motocraft website that you can just replace the alternator regulator.

Suggestions?

thanks

[phil-l]

Yes, when the engine is running, the vehicle's voltage should be in the 14V range. Your reading of 11 volts means the van is discharging the battery while running. Generally, this means the alternator is bad.

Hmmm - I'm not sure about the just-replace-the-regulator question; I believe the regulator is part of the alternator.

[LeSabre97mint]

Originally Posted by spmiller

Driving home on the highway last night, got an intermittent battery light on the dash. Not on solid, kind of half way, sometimes went away. Headlights were very weak.

When I got home I put a voltmeter on the battery with the engine off, read a little under 12v. Then started engine, and read just a little over 11 volts. If the alternator is fully working, shouldn't it read about 14V?

Anyhow, trying to figure out what went bad. I also see on the motocraft website that you can just replace the alternator regulator.

Suggestions?

thanks

Hello

Before you replace anything...check the small wire going to your alt. Mine was loose and giving me a intermittent light.


Edit***---I had a Ford Alt. tested at an auto parts and they said it was bad....it turned out (after replacing the alt, that it wasn't bad) that I didn't get the plug put back all of the way for my dash unit when I had it apart...that caused the charge light to come on.***---

Regards

Dan

[DRW1000]

A lot of auto parts retailers will bench test your alternator for you. You need to remove it and bring it in but it will take the guess work out of it.

I have replaced regulators internal to the alternator. Sometimes they are actually installed on the back of the alternator.

You could also have a bad cell in your battery that iss draging the system voltage down. However 12 Volts when not running though seems to indicate an uncharged battery more than a bad cell.

[wiswind]

Sometimes, the battery can go, causing a big load on the alternator, causing the alternator to seem bad.....or even go bad.
If the battery is 5 years old, or more, I would replace it.

On my '96 3.8L, there is a fuse "T" in the engine compartment fuse / relay box that can blow, causing the alternator to not work.....So I would also check that. It is one of those mini plug in fuses.

[garync1]

From what I understand some older models had a external regulator. The easiest way to check is to go to Advanced Auto or Auto zone and let them check both in the car with a load machine battery alt tester. Its free. If you live far away from one,you may want to pull them out and carry them in .its alot more work but it should solve your problem. They can test both in the store as well.. Hope this helps..

[ricebike]

to avoid lesabre's experience, check that wire... then have autozone/advance autoparts test your alternator/battery in the parking lot for free...