Battery light flickering while driving

Just hopped in my truck a few minutes ago. Started fine, batteries are strong. Started driving and got about a mile from the house when I noticed the battery light flickering as I'm driving. So I made a u-turn and came back home.

I noticed the light goes out completely at idle. Nothing. It only flickers while driving.

With the engine running I yanked out my multimeter real quick and checked the power at both battery terminals. Both showed 13.95 volts. Checked at the alternator, showed 14.12 volts at idle. Checked other constant power areas such as the hot side of the GPR and IAH relays, both registered 14.0 volts at idle.

I reformatted my hard drive not too long ago, and I haven't re-loaded AE yet. Guess I'll have to do that soon, that way I can hook up, monitor vehicle voltage, and drive around to see what my voltage looks like when the light is actually flickering.

All cables are fine. I've checked those again today, and I've completely inspected those recently. So there isn't a wiring issue. Looks like I have another alternator on the fritz. If I replace it, that will be #5.

Unless anyone else has other ideas I should check? I didn't expect to see such good voltage at idle. Every time my other alternators failed before, I could see voltage drop at idle.

check the plug on top of the alt. sometimes the way the heater hose is routed it puts pressure on that plug. Common problem with the OBS trucks. check the wire and the connection for breaks or corrosion

sounds like the brushes are loose. There are some places online you can buy the regulator/brush assembly for alot less than a rebuilt or new alternator.

Russ said:

check the plug on top of the alt. sometimes the way the heater hose is routed it puts pressure on that plug. Common problem with the OBS trucks. check the wire and the connection for breaks or corrosion

Click to expand...

:whs:

I know you said you checked the connections Curtis. I have seen where this connection looked perfect, but where it crimps in gets a lot of the wires broke loose. The boot hides it.

Just a reminder of the little things you can overlook.

Mine was doing similar this spring (regulator was failing), $300 for a new alt . . . so I spent $30'ish on a brush/regulator assembly and it's been working fine since.

:whs:

Unfortunately I didn't get a chance at all today to look at my truck further. Tomorrow I should have some time.

BTW, that large connection and wire was replaced end of last year because the other one was ***ked up. So it's a fairly new one, which is why I didn't think it would be bad. But who knows. I'll look at it closely tomorrow.

Mine was doing the same thing awhile back, then it went away, not sure why. So, in my case, the fix seems to be ignoring the problem.

Bet your bulb burned out.

No it still comes on at startup.

Big Bore said:

Mine was doing the same thing awhile back, then it went away, not sure why. So, in my case, the fix seems to be ignoring the problem.

Click to expand...

I det what happenned there was something got on armature (commutator shaft) naking a bad connection between there and the brushes. Eventually, the brushes cleaned it off.

Alternator is going out. Change it before it strands you at 5:30 in the morning in the rain in a waffle house parking lot.

It was the alternator. Swapped it out earlier today and no more battery light.

I checked all connections again, all the wiring, everything looked good. Never did hook up AE. I remembered that the alternator might have been under warranty, so I looked up my documentation and sure enough it was. Took it in, swapped it out, done.

Cool.

I was just going to offer one for you to test with... Glad you got it solved without being stranded first.

Sam

Lightning always strikes twice with me.

Fixed the alternator and had it done. Wife took the truck. Calls me 20 minutes later saying the parking brake is stuck. Fuuuuuuuuuuuuuuuuuuuuuuuuuuuuk

So I get there and sure as sh!t that pedal is mashed down... hard. And it wouldn't pop up. Asked my wife how hard she pushed the pedal. Her response was "I stepped on it as hard as I could". :doh: Managed to loosen the cable just enough to get the truck home without completely destroying the brakes or catching a tire on fire.

Anyway, got it fixed. FYI... if you ever push the pedal as hard as you can when engaging the parking brake, it's very easy to get it stuck. There's a release spring that will snap off to the side, and sure as hell it won't work if you pull the handle.

I swear to God I'm going to ban my wife from driving my truck. Sad thing is she owned a Superduty before. Now I'm wondering how in the hell that thing didn't explode.