alternator humming
Thread Starter
On The Tree
Joined: Feb 2009
Posts: 163
Likes: 0
From: Texas
alternator humming My alternator makes a humming sound when the cars off and it drains my battery any ideas why its doing that? It also gives my battery a low charge when im driving its charges right at the red line. Do i need a new one or what?
TECH Senior Member
iTrader: (3)
Joined: Oct 2006
Posts: 7,564
Likes: 4
From: Decatur, TN (N-W of Athens)
I'm thinking then that it's not your alternator. The only thing I can think of that could do that would be the voltage regulator, but if they tested it and it passed then I can't see that being the cause. What I'd do is get the battery charged up so it'll start the car and then unplug the alternator. You shouldn't have to disconnect it's post, but might as well just to rule it out fully. Then if the hum stays after a driving trip (mind you, just drive around the block as to not drain the battery), you can tell it's not the Alt. Or if it's a pronounced hum, then you could try the poor-mans stethoscope and place a socket extension (6"+ so you don't have to bend over) or a long screw driver onto the alternator. Make a fist around the end and place your ear up to it. It's not as specific as a real automotive stethoscope, but it works lol Works nice to rule out rocker tick too by placing it on the valve cover. But anyways, I think it to be odd if it is the Alt.
Thread Starter
On The Tree
Joined: Feb 2009
Posts: 163
Likes: 0
From: Texas
It only humms when the car is off it does not do it when the car is on...I unplug the wire on the bottom of the alt and the humming stops then I plug it back in it starts humming so can it be the voltage regulator
TECH Senior Member
iTrader: (3)
Joined: Oct 2006
Posts: 7,564
Likes: 4
From: Decatur, TN (N-W of Athens)
Coincidentally an automotive electrician (guy who deals in alternators and starters, rebuilding testing etc) swung into the shop to say Hi to the owner and I popped the question about your situation, he said it's absolutely impossible for it to hum while the vehicle is off. Also I said you had taken it in an had it tested, he just laughed due to how crappy those testing machines are and the fact the people testing them don't know (most of the time) what they're doing.
So I'm not sure what to say lol Unless your ignition is wonky and is somehow putting the car into a slight Key On Engine Off (KEOE) where its triggering the regulator, because he said that they won't activate w/o a signal.
Short of swapping alternators with either another F-Body owner or another GM vehicle, I can't think of any other tests.
So I'm not sure what to say lol Unless your ignition is wonky and is somehow putting the car into a slight Key On Engine Off (KEOE) where its triggering the regulator, because he said that they won't activate w/o a signal.
Short of swapping alternators with either another F-Body owner or another GM vehicle, I can't think of any other tests.
Trending Topics
Thread Starter
On The Tree
Joined: Feb 2009
Posts: 163
Likes: 0
From: Texas
Well i dont know what to do then...say some how it is putting the car into a slight Key On Engine Off (KEOE). How do i fix that or what els can it be that the ALT is doing that. It is the ALT making that sound i know and it does go off when i disconnect the clip in pulg on the bottom of the ALT and when i disconnect the battery. But i do have an other ? what color is the wire that runs from behind the motor with all the other wires that connects to the clip plug on the bottom of the ALT. The guy that had the car before me messed with alot of wires on the car like the fans the lights the wires under the steering wheel of the car the ALT and compressor wires and some wires with the ac because when i turn on the ac to see if it works smoke came out and it smelled like bernd wires. I have no idea what this guy was thinking before me that owned the car.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
