Hoping one of my fellow members here can help me out.

I've got a battery indicator 'warning lamp' that's on steady and I'm trying to figure out why. It was coming and going but most recently came on when I wound out the 460 hard in second gear. Now the batt indicator has been on steady for 2 weeks.

Checked the voltages with the engine off (12.38v) and with the engine on (14.45v) and I don't see a problem there.

Belt is new and tight, not slipping; battery terminals are wire-brushed clean and tight.

Any ideas what might be causing this? I hate to start parts-changing to figure it out, and I don't believe the generator shops and Pep Boys around here will hook me up and diagnose without wanting to do the fix.

Can ya'll help a guy out? Thanks in advance for any assistance!

zman

 

Actually most auto parts stores will test your alternator for free. Some will even do the test with the alternator still in your truck. This might be a voltage regulator problem internal to the unit. Might even be a connector problem. The battery light usually illuminates when the current draw from the battery exceeds that of the alternator output. Usually means the battery is the sole source of electricity, but in your case it looks like there is still some voltage output (over 14 VDC)but there may not be sufficient current to maintain battery charge. In most cases it usually means you will be walking soon.

 

when you get the parts store to check your alt, ask them to load test the battery and the alternator, to make sure they are performing under a load. could be that they check fine without a load, then when the load is applied, they wont hold up

 

Check the dash grounds and the single wire connector near the battery coming off the alt harness. That wire goes directly to the dash light, but has 1 or 2 resistors on the cluster.

 

Thanks as always for the replies, guys.

I have the CD ROM/Chilton for the truck and followed the load/no load testing procedures described, and the voltage readings appear to be in the ranges prescribed, I don't think I necessarily have a problem with the regulator/batt/alt. I think it may be a bogus indicator.
Time to clean connections, replace the negative batt cable that has a slit in it near the terminal (and showing some oxidation on the stranded wires), etc. I did put some dielectric grease on the connections indicated above going into the alternator, no change.

What stinks is that the neg cable is supposedly 91" long and not carried by the local auto parts stores, had to order it from Ford and it cost $40.00!!

What's really strange is that this indicator came on solid and hasn't gone out since when I wound out 2nd gear hard one night. That would lead you to believe it would be mechanical in nature, wouldn't it?


zman

 

Put a new voltage regulator on it before you are left stranded. I have a 91 F150 that did the same thing, light would flicker sometimes, and go out on long trips. But when i revved it up on the hiway it stayed on until i put the new regulator on it. Try it, it is only a couple of screws and is way cheaper than an alt.

 

Update:

Turns out that the voltage regulator is internal to the alt and has to be replaced as a unit, obviously.

Bought the alt tonight at Pep Boys (new) about $200.00 (ouch, ow ow ow)for a new one (rebuilt was around $129.00, wasn't chancing it) and replaced it, batt indicator is gone!!

Also replaced the ground cable to eliminate any current (no pun intended) or future problems with it. Ford hit me for $40.00 for it and it was only about 30" long, could have bought it at the auto parts supply store for about $15.00!! The only diff would have been there's an additional ground strap in the middle of the cable on the stock part and the regular parts store cable wouldn't have had that.
Can't have too many grounds, I guess! Cleaned all connections up real good while I was at it, amazing the amount of rust/crud that accumulates after 7 years!

Thanks again for all replies.....

zman

 

I bought the parts store cable, desoldered the middle terminal from the OE cable, and soldered in onto the replacement for cheap!

 

Unfortunately I didn't have time to check how long my neg batt cable was and the parts store guy couldn't tell me, nor could the guy at the Ford dealer, even though the dealer was looking at his computer and the part # at the time. The guy at the parts store thought it was 91" long!! By opening the hood and following the cable down by hand, with no time to play, I couldn't see where the cable ended because the connection was obscured by so much other crap.

Had I known the thing was only about 30" long I would have done the same that you did!!