Whining alternator driving me crazy, tried everything

[MichaelSE]

My alternator whines like hell. I have been dealing with this for months, and I'm sick of throwing time and money at it, hopefully one of you can point me in the right direction.

The whine goes away when the battery charging cable is disconnected from the alternator.

It's a whine from the engine bay and does not come through the speakers.

Here's what I've tried so far:

1. 2 new alternators. The one that was in the truck when I bought it made the lights flicker, but didn't whine. I replaced it. This one whined. I believed it to be defective so I got it replaced by Amazon. The replacement does the same.
2. New battery. Mine was rated for 730cca and it came in at 640, so I replaced it. No difference.
3. Disconnected the connector near the battery that controls the variable charging system, as suggested in another thread. No difference.
4. Took apart the main 175A fuse box and cleaned all connectors, put dielectric grease on them.
5. Followed the positive and negative battery cables as far as I could looking for fraying. They look fine.
6. Pulled the belt off to check the pulley bearings on both alternators. They spun freely.
7. Used the multimeter to check voltage between battery-block, battery-body, body-block all 0.0 volts.

The battery reads a pretty consistent 14.8 volts while the engine is running. The alternator puts out a very consistent 14.8 volts from the stud. When the control wire is disconnected, it puts out 13.4-13.5 volts.

Any ideas? Thanks in advance.

 

[sumo]

What's the brand on the alternator? Had experience in the shop were customers installed aftermarket alternators for a complaint whine. Turned out it was the brand of alternator they chose. Installed oem and problem went aeay

 

[MichaelSE]

It's a Remy International alternator. Both were brand new, not reman. Maybe they just make shit alternators. They won't replace this one and I won't spend another $120 on a new alternator. I think I might go to the scrapyard and pull a used alternator off an NBS Silverado and try that.

 

[Denali Homie]

When I had alternator whine my alternator was going bad, and (more importantly) couldn't handle the load placed on it (vehicle load + car audio system). It's possible those new alternators don't put out enough power in the right rpm ranges for you, new or not. This is sort of confirmed when you remove the battery charging cable and the whine goes away. It's at that point all the electronics are being run off the battery. If the alternators are whining with all auxillaries off (headlamps, hvac, radio, etc.) then it's likely putting out lower power than stock.

 

[MichaelSE]

When I had alternator whine my alternator was going bad, and (more importantly) couldn't handle the load placed on it (vehicle load + car audio system). It's possible those new alternators don't put out enough power in the right rpm ranges for you, new or not. This is sort of confirmed when you remove the battery charging cable and the whine goes away. It's at that point all the electronics are being run off the battery. If the alternators are whining with all auxillaries off (headlamps, hvac, radio, etc.) then it's likely putting out lower power than stock.

I'm just worried that something else, like a bad ground, may be causing the issue and it will just reappear in the third alternator I throw on. My Suburban is stock with no system or extra lights, and the alternators were 160 amp which the RPO calls for.

 

[MichaelSE]

I'm going to bump this back up since I am still dealing with this issue and it is still driving me insane. Any help would be appreciated. At this point I have a new battery (12/2017 manufacture) and I'm on my 4th alternator, an ACDelco OEM, and it is whining -- in fact, it's both whining and making the lights flicker, and I am at my wits end with this. The dealership says both the battery and alternator test out fine. Someone please help.

 

[Doubeleive]

I might suggest throwing some old school fixes at it like a ground loop isolator and/or ferrite. it's not right fix but it should work.

 

[Doubeleive]

something like this
https://www.ebay.com/itm/LINDY-Ferr...979778&hash=item5b33cd9ff6:g:2KoAAOSwR6RaCYS4

 

[Doubeleive]

and have you tried new ground cables or doing the "big 3"

 

[RED TAHOE LS]

Alternator whine is caused from MAX charging rate the BATTERY is asking for.

The load control connection was designed for GAS MILEAGE just like my Honda has. Unlike your vehicle, my Honda has a ELECTRONIC LOAD DETECTOR that does the same thing, it tells the alternator when to add more charge to the battery, which in turn helps mileage. How do I know this, I had a battery problem and changed the little detector, problem solved.

That little HONDA detector was located in the fuse box (under hood) about the size of a book of matches and black in color. You should trace from the cable you talked about and locate the control unit and replace it. JMHO and good luck.
David g......

 

[MichaelSE]

something like this
https://www.ebay.com/itm/LINDY-Ferr...979778&hash=item5b33cd9ff6:g:2KoAAOSwR6RaCYS4

Thanks for your replies. Would this help even if the whine is not coming through the speakers? As for the big 3, I have not upgraded the ground cables themselves. I have traced them and made sure they were all secure, but haven't changed the cables.

That little HONDA detector was located in the fuse box (under hood) about the size of a book of matches and black in color. You should trace from the cable you talked about and locate the control unit and replace it. JMHO and good luck.
David g......

Thanks, I'll take a look under the fuse/relay box and see what I can find.

 

[Doubeleive]

its just an idea to try, if it works for the sound system I don't see why it wouldn't work for the engine electrical system just as well, I would think the dealer would have checked the grounds and/or to see if something that is not supposed to be grounded is being grounded, maybe something is causing some resistance and giving feedback as a whine, maybe leave the alternator connected and try to troubleshoot the system by removing other powered systems one at a time until the noise goes away I would think that would narrow it down, maybe doing something as simple as pulling fuses one at a time while it is running.

 

[MichaelSE]

maybe doing something as simple as pulling fuses one at a time while it is running.

Actually that's a great idea... which fuses and/or relays should I pull? Does it risk damage to pull any while it's running?

 

[Doubeleive]

Actually that's a great idea... which fuses and/or relays should I pull? Does it risk damage to pull any while it's running?

take your pick start in one place and move to the next, I think worst case scenario you might get a CEL or it will stop running until you replace the fuse and restart, I mean I would start with the basics, lights, horn, blinkers, etc and work your way up

 

[MichaelSE]

Well I've pulled every fuse I can think of, still whines. Replaced all ground cables, still whines. Tried a 145 amp alternator, still whines. Tried a 250 amp alternator, still whines. Gratuitously sprayed electronic cleaner on all contacts I could find, still whines. Replaced battery charging cable, still whines. Local mechanic can't figure it out. Dealership can't figure it out. I give up. Any other ideas?

 

[kbuskill]

Well I've pulled every fuse I can think of, still whines. Replaced all ground cables, still whines. Tried a 145 amp alternator, still whines. Tried a 250 amp alternator, still whines. Gratuitously sprayed electronic cleaner on all contacts I could find, still whines. Replaced battery charging cable, still whines. Local mechanic can't figure it out. Dealership can't figure it out. I give up. Any other ideas?

Does the whine change when you disconnect the plug and the voltage drops down?

Does the whine change when you turn ON EVERYTHING... High beams, seat heaters, rear defroster, front and rear blower motors on high, ETC. ???

My next suggestion would be to lift the fuse box under the hood by flipping the gray handles up/In and lifting it up exposing all the connections and spray them all down with contact cleaner and letting it dry and then put some dielectric grease on them and reseat the fuse box and see what happens.

It sounds like the ECM, or whatever controls the charging rate, is telling the alternator to charge continually. Or perhaps a bad diode in the alternator, although this seems less likely since you have swapped alternators several times.

When you disconnect the sensor around the ground cable by the battery does that change the sound OR the voltage output? If not perhaps this sensor is bad and is calling for charging all the time, like when it is unplugged.

 

[MichaelSE]

Does the whine change when you disconnect the plug and the voltage drops down?

Does the whine change when you turn ON EVERYTHING... High beams, seat heaters, rear defroster, front and rear blower motors on high, ETC. ???

My next suggestion would be to lift the fuse box under the hood by flipping the gray handles up/In and lifting it up exposing all the connections and spray them all down with contact cleaner and letting it dry and then put some dielectric grease on them and reseat the fuse box and see what happens.

It sounds like the ECM, or whatever controls the charging rate, is telling the alternator to charge continually. Or perhaps a bad diode in the alternator, although this seems less likely since you have swapped alternators several times.

When you disconnect the sensor around the ground cable by the battery does that change the sound OR the voltage output? If not perhaps this sensor is bad and is calling for charging all the time, like when it is unplugged.

t

The only thing that stops the whine thus far is completely disconnecting the battery charging cable. Disconnecting the control cable does make it change in pitch, but it's still there, and same for turning on all accessories. I will try removing the fuse box this weekend - does it have a single large connector underneath it? I'm also beginning to believe it's something with the ECM and I plan to swap back to stock tune for a little while and try that. Yes, disconnecting the variable rate charging cable does cause a change in output (makes it slightly higher) so I believe that system is working as intended.

 

[Doubeleive]

have you tried adding any additional wiring like a power wire straight from alternator to battery post?, ground from alternator to frame, I recommend using "0" gauge and copper connectors.
I figure at this point it couldn't hurt.

 

[MichaelSE]

have you tried adding any additional wiring like a power wire straight from alternator to battery post?, ground from alternator to frame, I recommend using "0" gauge and copper connectors.
I figure at this point it couldn't hurt.

Do you mean straight from the output terminal to the battery terminal? So that there are 2 wires coming from the output terminal? And would it go on the positive or negative battery terminal? I'll have to get a shop or a buddy to help me with that one, I'm kind of dumb when it comes to adding wires (I can only replace them) and I'd probably set something on fire

 

[MichaelSE]

It sounds like the ECM, or whatever controls the charging rate, is telling the alternator to charge continually.

I had a question about this. If something were causing the alternator to charge continually, would it be reflected on the voltage gauge on the dash? I.E. always above 14v?