When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My lights dim and my voltage gauge drops to the N at idle with accessories going, fan, radio etc. Truck is totally stock. I had the alternator tested and it came back as “bad charging current.” I swapped it out today with a junkyard Motorcraft alternator. No change. Any ideas? Thank you.
Thanks yeah I’ll try the grounds. I had the charging system checked and they said it passed. The engine runs slightly rough when the voltage drops like this which leads me to believe it’s not a gauge issue.
One thing which can help would be cleaning up where the alternator contacts the motor. A good connection there makes a good ground for the alternator. Another thing which you can do is add a ground to the alternator directly to the battery.
That’s a good idea. I went down the rabbit hole last night with doing voltage drip testing. I hate doing junkyard parts because that alternator I put on is likely just as tired as the one I replaced.
You can always clean up the alternators before you put them in. I just performed this on my 1999 rav4 today. took about 20 minutes to take the voltage regulator off, clean the rectifier, clean where the rectifier attaches to the rest of the coil.. There was minor amounts of dirt/corrosion. Also gives you a chance to look at the stator and the brushes. Which you can replace(the brushes that is).
Here are a few links to 2g and 3g alternator rebuilds. Mike Laeur is a great youtube resource. Usually I watch the video than go and do it. Makes it real easy.
Dude I’m gonna try taking apart the old alternator. My hunch is the problem lies within both alternators and that they’re just tired. The problem is intermittent but got loss intermittent with the second junkyard alternator. I’ll cleaned the mounts like some suggested as well and go around and clean grounds too. We’ll see.
I found this article. Sounds like my issue is an underpowered alternator. I also found this video from the minute masters guy. He does some pretty good videos. As others suggested I think a 130 amp alternator will solve my issue.
It doesn’t dim too bad but the voltage drops to the n sometimes at idle with the fan lights and radio. Then the engine kinda stumbles. I’ll check that link again. I cross referenced what vehicles had the 3g 130 amp version and think I should be able to find a decent one at the pull and pay
I believe its normal at Idle for the voltage to drop with a load on it. The alternators are outputing less amperage than what the alternator will at 2200 RPM engine speed.
Same thing happens to my rav4 with the fan/lights on at an idle.
Try this, put your volt meter on the battery at idle. Most likely its around 14.6VDC ~ Next turn your fan/lights on. Voltage will drop. Next rev the truck up and notice the voltage jump back up.
I am not sure a 130amp will prevent the lights dimming.
Thanks yeah I’ll try the grounds. I had the charging system checked and they said it passed. The engine runs slightly rough when the voltage drops like this which leads me to believe it’s not a gauge issue.
The same thing is happening to me and renate two wheel drive 5.0 1992 f150 it seems to only happen when I am coming to a complete stop at idle or a neutral as well and has died while driving. If you have any updates please let me know.
