Hi all,

I've been having an intermittent whine in my LS430 that changes with engine RPM and is most present under heavy electronic load at idle. I bought a cheap multimeter from harbor freight and performed three tests, comparing it to the internal diagnostic screen's measurements:

1) With the car completely off (no lights, nothing):
- HF multimeter: 12.3-12.4V
- Diagnostic screen: 11.6-11.7V
-No whine

2) With the car running but all electronics off:
- HF multimeter: 14.3V
- Diagnostic screen: 13.3-13.6V (not sure why it fluctuates so much)
-Very, very faint whine, may just be me trying to hear a problem.

3) With the car running and as many electronic things on as possible (A/C, high beams, heated seats, cabin lights, etc.)
- HF multimeter: 12.2-12.7V
- Diagnostic screen: 11.0-11.6V
-Significant whine.
During this test, the car had already been running for around 5 minutes with no electronics on while I performed test #2, and I noticed a steady drop in voltage from the top end of the scale to the bottom end over the course of 5 minutes, though it stabilized after this point and stopped dropping. I may perform a longer test to see if it keeps dropping, in which case I'd think the cause is likely alternator-related.

All of these tests were performed at idle. When throttle is applied until 2000 RPM, the internal display jumps back up to 12.3-12.7V, which would probably be 13.3-13.7V with the HF multimeter due to them being apparently exactly one off from each other. With throttle application, the car Additionally, the whine is most prominent during the third test when the car is under a heavy electric load at idle as well as when the car is started for the first time after not being run for a few days. I have had 0 issues with slow starts or cranking, but do observe drops in idle RPM to around 600 after around 30 minutes of driving or idle RPM dropping from 750 to 600 when I turn off the climate control/air conditioning in hot weather.

I'm currently running a Duralast battery that's 6 months old after I replaced my 5-year old Interstate battery due to code P3051 showing up (this had initially occurred due to Valvoline overfilling my oil to 9 qts instead of 5, but the code had returned after some time anyways, and I read online it cleared the issue for someone after going through basically every fix I could, and it did and the code has not come back in the 6000 or so miles since then). The battery test with the car off doesn't seem to indicate an issue and autozone's own testing showed no issue. I also took the car to my mechanic today and they ran a start/charge test with heavy electric load and could not find fault with either the alternator or battery. I'm at a bit of a loss here, as I don't know whether to just try replacing the battery and see if that fixes something before trying to tackle the alternator, or if it could be something else entirely. I have not taken the serpentine belt off to check any pulleys but there's no sounds that are evident with electronics off and no play in the belt or evidence of cracking/age.

The whine sounds almost like the car is supercharged when it's really bad, but is not noticeable at speed, and only becomes prominent when slowing down below 15 mph, and the pitch noticeably changes with the RPM as the car downshifts when coming to a stop, almost like a straight cut gearbox. I was also told I have a leak from the transmission pan gasket and oil pan gasket but fluid level looks fine for both and fluid looks clean (changed 17k miles ago for trans, 2k miles ago for oil, but I am a dunce and reused the old oil drain pan gasket). Any thoughts?

 

Get a length of hose. When the whine is present, put one end of the hose to your ear and probe around with the other end to isolate the origin of the noise.

 

You already closed in on the culprit...and my bet would also be on the alternator and/or voltage regulator within it.

There's zero correlation between the transmission and the whine, as you said the change in the electronic load makes significant changes in the tone/pitch/volume of the whine.

Here's a simple video showing the electronic whine/noise from bad alternator...

 

The use a couple voltage isolators on the motor to keep the alternator from interfering with the stereo. They aren’t expensive or hard to replace, one of yours could be damaged or something, I would definitely start there. I will get you the part number if you need it?
or your alternator could be full of power steering fluid like a lot of 3UZ’s, have you had your power steering pump rebuilt? If not, I would pull it off and see how bad it’s leaking and if it’s ruined the alternator? It’s inevitable

 

I think the voltage thing is actually caused a silencers. Without mouthed the stereo speakers pick up the noise from the alternator and it sounds terrible but it’s an easy fix.

 

So I was poking around again, I know some people get the noise through their audio system but I've never found that to be the case for mine. The whine, while barely audible at points, is 100% coming from the alternator and from talking to a user on Reddit, they had similar voltage readings and issues before the alternator finally went 6 months later, so I'm probably going to just replace it sometime soon. The whine in the video posted above pretty much exactly matches the sound I'm hearing, except my sound is much quieter (though it was this loud the first time it happened). Unfortunately, I've got a backlog of other work so I'm probably going to delay replacing it for a month or two, fingers cross it'll be okay. Should I consider replacing the voltage regulator too? That hadn't crossed my mind and I'm not sure how I'd do it.

 

The voltage regulator is inside the alternator.

If you do replace the alternator, try to find a new/rebuilt Denso unit; they're getting hard to find. If a rebuilt Denso, be sure it comes in a Denso box.

 

I think the problem is caused by a dead rectifying diode in the alternator. A skilled guy would replace it but this is not for everyone.

 

You’re going to find the alternator in full of power steering fluid. Plan on replacing the pump, reservoir, the 2 hoses the come off the reservoir, the 2 vacuum hoses and the serpentine belt. I would inspect the valve covers for leaks, they probably also leaking and need the gaskets and spark plug tube seals. While you have it apart, you might consider doing the water pump and timing belt, because the only thing left to remove will be the timing belt covers and the A/C compressor. And then you should be in good shape for many years.

 

I checked regarding the power steering and oddly enough, there's no sign of any leaks. I actually had the fluid flushed a few weeks back thinking the whining noise was power steering related (sounded like a bad pump I had on an old Avalon I used to own), but it turned out the system was working perfectly fine besides the fluid being old. It seems like something in the alternator has just failed after so many years, though I recently moved to the Midwest and wonder if the harshness of the Winter was particularly hard on it. Besides that the only leak I've observed so far is from the oil pan (I reused the drain pan gasket when doing the oil change because I'm a dunce). Honestly impressed how decent the condition of the car is after this many years.

 

Alternator whine is caused by dying bearings, not by the electrical side of the Alternator.
Fit a reconditioned/new Alternator and the noise should go away.

If you have a whine inside the cabin but not in the engine bay then the electrical noise suppression has failed in the Stereo system.