Evening Gents.

After searching and reading a few threads on a battery light issue, I'm looking for a little clarification/direction.

2006 V8 AWD. 217k. Timing belt and water pump done at 215k, serpentine done at 208k. I have NOT done the secondary air bypass, but I do have the kit in my garage ready to go.

After having my Toyota dealer install the timing belt and water pump, I noticed in the mornings the truck would make a whirring sound with what I thought was a fan clutch engaging and disengaging. It would not do this when the truck was at temp.

I got a battery light a few nights ago. Took it to Autozone and had them test it and the alternator. The battery wasn't doing so hot, and the alternator came back fine. Slapped a new battery in with 750 cold crank.

After putting the new battery in, the battery light did not go away. The whirring has gotten more noticeable. Video here.

Gut says alternator. But I've also seen posts regarding ground issues at the fender, alternator, or ECM.

Electrical testing shows the battery at a 12+ V reading, and when running and with throttle it jumps to 13-14, so that says the alternator is functioning, but the whirring tells me it is on its way out? Or is it something completely different like a dying powersteering pump or... something else?

Thanks for your time and opinions.

Unplug the alternator and see if noises change. If yes, then bad alternator. I'm pretty sure it's bad alternator. Also check to see if that power steering pump isn't leaking down onto that alternator.

I would suspect a bad alternator being the battery light is on.
Does the voltage drop once the whine starts?

Nope. I almost wish it would have, would have saved a post and I’d have a new alternator on the way by now!


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Never thought about it leaking. These noises / issues started after Toyota put the timing belt on. Do you think something could have happened on the reinstall that caused the leak -> subsequent alternator failure?


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Went through something similar for about 9months. Had a really weird whine/groan that thought was the power steering pump. Would come and go and usually only happen during the first start of the day. Fast forward and I'm about 2 days away from buying a new PS pump and the battery light comes on. Alternator the whole time.

Just for funsies, I took the bad Alt to Autozone to have it tested and it PASSED. So take that for what it's worth.

I also replaced my acc belt with the alternator and made things a lot more quiet. Guessing the old one was stretched. Maybe the new one put enough more tension on the alt to kill off marginal bearings?

Went with a Rebuild from Partznet and am happy.

I used to work at AutoZone, while in college. The alternator test is not full proof. There has been several occasions in which I tested a bad alternator that tested good. In many cases a bad alternator works better when cold (on the bench test) and when the engine first starts (higher rpm for minute or two). In this case it would typically be a bad voltage regulator. On the other hand if the diodes in an alternator fail then it will always test bad.

Were you able to unplug it? Might have access through the passenger side apron.

Not yet. My work week has been keeping my in front of a computer all waking hours instead of my toolbox. Friday I’ll tear into her. Have a new alternator just in case, and it’s time for plugs, oil change, and secondary air bypass.


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Sounds like mine when the alternator went

My truck did the same thing when I used a winch for too long. It just smoked the alternator and the light came on. Once I slapped in a new alt, everything was good.

Well. My alternator arrives today. Which is good because my truck died on me last night driving home. Luckily it died in my neighborhood walking distance from my house. Got it to start with a quick battery charge and got it back to my garage.

Thanks for your input all. Turns out the best way to confirm a troubleshooting exercise is to experience a failure.


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Keep us updated!

I’ll be tearing into it in a few hours. Wish me luck haha


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Alternator swapped. Started at 7:30 pm ended at 9:22 - had a buddy and a half help (the half showed up to tighten nuts on the new alternator, steal a beer and leave).

Full write up when I’m not on my phone.


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