99 F350 Intermittent Batt light, no charge

AlanB · Nov 9, 2009

Of all the problems I hate, an intermittent electrical light has to be one of the worst.

99 F350 dually diesel 4wd loaded (not sure that it matters but thought I would lay the groundwork)

New Autozone alternator (this is the single alternator version)

Getting an intermittent Batt red light on the dash, sometimes voltage drops and sometimes, not (reading the dash gauge) have never got the red light to stay on while reading with a voltmeter.

Ran on Autozones checker and everything checked ok, light NOT on, pulled out of the parking lot, light comes on, turned around, pulled back into lot, light goes off.............

As long as I can drive around in the autozone parking lots I should be fine

Anyone run across this one by chance, going nuts troubleshooting as I swear every time I check, light is off and everytime I drive light is on. I think it has a meter sensor that when I get within 10' carrying a meter it straightens out.

Side, and possibly related note, my AC seems to die (not blow cold) when the voltage is dropping and light is on, I am assuming it is an effect of the voltage drop and not a cause of the voltage drop.

Ideas appreciated as I think it is stab in the dark time if I can not make it duplicate while checking it.

Thanks

Al B

HarryVanderpool · Nov 9, 2009

I had the same problem last spring on my '99 F-450 loaded.
Intermittent battery light, no AC.
It was one bad diode in the Alternator.
Check your harness and otherwise take the Alt back to Autozone for another one.

jayste · Nov 9, 2009

I agree. I've got a '99 F250 and had similar problems once. It was the alternator. Once I read you had an Autozone alternator I figured the same thing. There's a reason they have a lifetime warranty. You keep coming back for a lifetime!

No, really I've been fortunate on occasion and have gotten some good products there just not alternators.

Jay

Diamondpilot · Nov 9, 2009

Could you have a slipping belt? Seems like the ac problem and the alternator could be tied together. Maybe just coincidence but could be related.

Chris

tractorski · Nov 9, 2009

Check all your grounds and connections to make sure they are tight and clean.

dodge man · Nov 9, 2009

I learned on thing a long time ago, never assume a brand new part is any good. In your case, it probably isn't a brand new part, but a rebuilt one.

Years ago vehicles used to have voltage regulators, which was a seperate box, and these would go bad. I don't think newer vehicles have a seperate voltage regulators anymore, but there is some kind of device that controls the voltage of what is coming out of the alternator, I just don't know how or where it is.

Mike Costello · Nov 9, 2009

These days, most alternators have integral regulators built into the alternator, so one replaces the other if bad. Also, altenators have six sets of diodes in them and its possible to get a red light and still show a charge. Replace the alternator.

AlanB · Nov 22, 2009

While I am seldom impressed with the quality of AutoZone parts, I cannot fault their service today. Finally had a chance and pulled it today, walked in, man said how may I help you, I said this thing is intermittently working, every time it comes in an Autozone parking lot it is OK, when I leave I get a light, he said let me get you a new one.

New one is on and first run went ok, I hope it holds up.