Red battery light

Hello all

Red battery light pops up this afternoon, I thought may be battery, swapped the battery with another known good battery and the red battery light is still on. So I guess the alternator is gone. Before me switching the alternator for another one, do you think I can get away with just changing the brushes? I really don’t want to throw in an alternator if I don’t have to.

I started out with an 04 Tacoma TRD V6 5speed but the frame was rusty so I went out of my way and find a low mileage 2000 Tacoma V6 5speed. And so far I have more problems with this 2000 unit than my rusty 04

 

Same amount of work. Still gotta pull the alternator. I'd just throw in an AutoZone lifetime warrentied unit. I've been running one for 3.5 years.

Our 1st Gen Tacoma alternators change out pretty easy.

I just got done doing an alternator on my 2nd Gen Tundra. That job took me 6 hours.

 

Ok, thanks for the quick reply. I was actually worry about the AZ alternator, I rather rebuild the stock oem than put in an AZ unit, but if your last 3.5 years than I’ll be ok with that. Yes the alternator job on these first gen is cake walk

 

You could always grab clapped out alternator to use as a core. AZ doesn't care that it's not like for like.

Keep your original and rebuild it for $20 and have a spare. Never a bad thing.

 

brushes are cheap. you'll know if they're gone as soon as you open it up. i would order the brushes at local dealer and pull the alt. if you determine the whole alternator is bad just replace with a denso and cancel/ return the brushes. they're available at napa and maybe other places.

btw brushes is one of those things that should be added to a timing belt job.

fortunately on the Tacoma pulling the alt is easy. on my landcruiser it's nearly the same work to pull alt as it is to do a timing belt

 

That’s a good idea.

 

that’s why I still love these 3.4 V6. So simple to work on and ultra reliable

 

Yes the brushes. The original Denso unit won't have some hack that has 'remanned' it. The original Denso alt is a high quality unit. It would be wiser to change just the brushes, keep the better unit and save coin

 

I really hope you don`t swap the alternator to find that is not the problem.

Unless I missed it just how did you figure it was the alternator ??

The plug on the alternator if getting old and worn tends to corrode wires are good for getting brittle and breaking from thermal cycling .

 

I got the red battery out of no where. Drove the truck home and every lights get dimmer as the time go. Got home, swap the battery from another truck, everything fine except for the red battery light. So my guess would be the alternator, unless there’s another thing that I have to worry about.

 

If your light gets dimmer as you drive, the alternator is not working properly. The accessories are run off the alternator when the engine is running. The main purpose of the battery is for starting the engine. Time to check the brushes or replace it altogether.

 

I had the exact symptoms as you, put new brushes in, and cleaned up the commutator, alternator runs like new. Don’t get rid of your OEM unit they are high quality!

 

Got some good news. Took the alternator off and the brushes are worn out. Swapped the new brushes in, bolt it up, started the truck, red battery is gone. From the look of it, I’m very sure the brushes are original to truck. I’m happy that I retained the original alternator. The whole job may take an hour total. Thank you guys

 

Great work man. It makes me very happy you didn't exchange that high quality unit for some reman garb. It really is wise to keep the high quality OEM unit.

 

I was going to say check the alternator fuse and check for voltage when the engine is running before you go through the trouble of removing the alternator. Well, you guessed right. Glad to hear it was just the brushes. They typically last like 120-150k miles depending on usage. It would have been good to test the rectifier diodes while you had it apart. You can have a bad diode and the alternator will still work but at reduced capacity. You'd never know unless you use a lot of accessories at the same time.

I also always recommend getting one of those cigarette lighter outlet USB chargers that has a voltage reading. That way you can monitor what your normal voltage should be. Sometimes it will start getting low around 13 volts without the built-in warning light coming on. That would be an early indication that something is going wrong with the alternator.

 

Are the alternator brushes available through a Toyota P/N, @TacomanTurd? Any references would be useful to have in this thread. Any pix of the steps in brush replacement, too, would be helpful.

 

I didn't know this about the defective diode and reduced output, that there could still be enough juice made that you wouldnt notice bad diode... I'm gonna have to look into that more for my own experience.
On the blown diode, is it usually visible when you open it to inspect it? Or would the be tests or measurements you take while it's running to check this?

 

You might be able to notice by checking AC voltage at the battery with the engine running. It should be smooth, no AC voltage.

You'd have to look up a picture/graph of what the rectified voltage looks like. With one bad diode you would get 14 volts for 2/3 of the rotation of the alternator then it would drop to near 0 for 1/3. The battery would make up for this and smooth the voltage out so you'd never really notice, just a very slight variation of voltage that a voltmeter might pick up on AC setting.

The definitive check is to remove the rectifier and check each diode with a multimeter. It's not hard to remove after removing the brushes. It's just 4 screws. There won't be any visible sign. I'm sure there are videos and write-ups showing how to do this.

 

P/N

$25 27370-75060 Toyota Parts - Holder Assy, Alterna (27370-75060)

27370-75060 for the alternator brushes + holder for my 2003 DC 4WD TRD, and probably for a lot of the other engine/drivetrain combinations, too, and even quite a few other Toyota models. About twenty bucks at the dealer.