Voltage Spike

Hey yall,

Ran into another problem with the truck...

While driving, at times the stock voltage meter will spike up towards the 18 mark flashing the red battery light.

Took it to autozone, they told me it was the battery. The PO did say the battery was more than 4 years old so I decided to replace it. Alternator also looks recently replaced.

There are no other symptoms and nothing happens when the spike does occur. The car feels normal and keeps on driving. Even with the old battery, she didnt leave me stranded. I do know overcharging the battery is a bad thing.

Anyone know what this could be?

 

Here is my problem visually:

https://youtu.be/MlFUlIJUdlU

 

And at idle no less. That seems like it would be maybe the voltage regulator in the alternator?

 

That is at idle. Pretty much remains the same as I drive. When the light doesnt flash on it sits where it is in the video, below the dash before the 18. And at random times when driving itll shoot up to the 18 and flash the battery light.

 

Alternator. As they fail they classically lose amps but increase voltage.

 

Thanks for all the suggestions guys.

Tomorrow I'll head over to Autozone to get the alternator tested.
I'll also be checking the grounding connections.

If it ends up being the regulator, would it make more sense to just get another alternator? Looking online, it looks like the regulator is close in price to just buying another alternator.

 

Yes. That is standard practice these days as most vehicles no longer have separate voltage regulators but rather have them in the alternator and its not really worth it to rebuild them.

If its an intermittent problem it may test normal when its not acting up.

 

If you're pulling the alternator to have it checked you may as well take the battery too. Get em both checked and save a trip.

 

So I went to check the alternator over at AutoZone, everything came back good. So I'm guessing it is the regulator.

Already have a denso one on the way.

I'll keep the post updated.

 

How many miles on your 01’?

 

Interesting the price difference in these alternators. Wonder if the 130A (cheaper) is pull and play with the 100A (almost twice the price)?

 

It has 210,000 miles on it. The alternator does not look original though.

And wow, now I'm really hoping it's just the regulator, that's a lot of dough for either of those

 

Yes. Pretty steep. I wonder if the online retailers can do better pricing or even have availability on the OEM?

The higher amp alternator above is less expensive by $200! Wonder if it will work?

 

Higher amp units are usually just spec'd on higher trim models. No problem with replacing a lower amp one since the wiring is typically the same for either.

You can pick up a new (not reman) parts store brand or a reman Denso for about $250.

 

Or just get one off Amazon for $100

 

OEM?

 

Seems like it would be better to buy an entire new OEM Alternator for a little bit more money and way less work and risk.

 

No. Something like this.

$177 DB Electrical AND0279 New Alternator For 4.7L 4.7 Toyota Tundra 00 01 02 2000 2001 2002, 4.7L 4.7 Sequoia 01 02 2001 2002 102211-0610 13859 ALT-6213 27060-0F020 1-2276-01ND

https://www.amazon.com/DB-Electrica...y&sprefix=2000+tundra+alternat,aps,197&sr=8-5

Or a rebuilt Denso for $50 more.

 

I was looking for that darn diagram prior to taking the alternator off when I got home from school lol.

A refurbished denso regulator with a 2 year warranty is already on it's way so there's no going back now lol.

Regulator was only about $30, which isn't too bad.

 

Take some pics of the opened up alternator. I’d like to see the brush inside.

 

No matter where you buy the alternator, take it somewhere and have it tested. My grandson ordered a new alternator for his car from Rock Auto. When we went to install it, I insisted we have it tested. It failed miserably. I bought a new one on the spot and had it tested. It was good. The test saved us a lot of time and grief. When the alternator failed on my Mom's truck, I went to O'Reilly to pick up a new one. It, too, failed when tested. I had to go to a second O'Reilly's to get one (the first only had one in stock), but the second one passed.

 

Will do, model.

Very wise words, I've seen this happen to a couple of customers too when I worked at AutoZone. They got their "new" one installed and it failed within the week. They'd come back understandably mad...

 

FYI the alternator is a pain in the D to change. You have to remove the power steering pump.

 

This is why I only buy new starters and alternators every reman I've had I replaced shortly afterward.

 

Not on a 1st gen 4.7L you don’t.

 

Oh. Yes true. It also doesn't take 10 hrs to swap a steering rack on a 1st gen either haha

 

Did not know this. Thanks.

 

So here's an update guys...

Installed the regulator (forgot to take pics, sorry handmodel!), stock gauge does not spike up anymore, however, the battery light still blinks when I drive, not as often but it's still there. It flashes on and off real quick at random times so it's hard to say under what conditions I could trigger it in.

I'm thinking about looking at the grounding points. Tried looking for the locations on here and other forums but didn't see what I should be looking for. I know there's a ground point coming off the battery, but that's about it.

Any ideas y'all?

 

Did you check out the brushes while you had it apart?