Battery light came on and stayed on in the middle of december... Got battery and alt tested numerous times at different places and both were good... Light still came on so I decided to replace belts while I had the alt off... Replaced belts, and BAM! No more battery light for over a month and 2 thousand more miles on it.... Until 2 days ago... It came and stayed on for 45 miles.. Then went off.... Then came back on yesterday AM when my dad drove it to work (I was heading to AU (Roll Tide!) and didn't want to get stranded)....

I'm going to replace the battery and see if (maybe-- hopefully) it solves the problem.. However, I'm inclined to think it's the alt...

Any ideas?

98 T4R 3.4V6 Limited

 

Seen and heard numerous times alt testing good still bad, especially reman crap.

:wabbit2:

 

Factory Denso Alt.. 280,000+ miles.. Thanks, wabbit!

 

Don't get a reman. Rebuild that one.

:wabbit2:

 

I agree with you wabbit! I had forgotten I could rebuild mine for way cheaper than buy one.. Any particular place to get the rebuild "kit" from? Looked at mobi-arc, but I dunno..

 

It's usually just the brushes. Only a few dollars at the dealership.

 

Anything else needed other than the brushes? Stator?

 

What did they supposedly test? An alternator, as the name implies, generates alternating current (AC). It could be the diodes inside. It could be anything. You need a professional with professional tools to look at it.

 

On a whim, I decided to test batt and alt with multimeter. 12.12 volts on the battery with the 4Runner off. 11.3 volts with it on and a load. Alt is definitely bad. Picking up parts tomorrow to rebuild..

 

WABBIT ROCKS!!!! It was my brushes. Replaced and all is well. Wabbit, holla if you ever need help with anything in North Al!

 

I owe you one as well! If you ever find yourself in Huntsville, AL, I'll buy ya a beer.

 

Haha thanks man...glad I could help.

 

Maybe you can help me troubleshoot my issue too. Two days ago the ABS and battery light came on. The battery light would flicker, go out, come on but the ABS stayed on. Used the multi meter and had 12v with engine running, 10v off. Bought a rebuilt denso 80A alternator and replaced the old one tonight. The ABS light is now off but the battery light is on constantly. Testing again with my meter, i get 10v. So i took it to advanced auto for a warranty check and their meter tests it at 12.42v engine off and 14.6v running. My read is the battery is below 80% charge. They tell me they wont replace the battery yet.

Battery is an Optima Red top bought in 4/2012

So did my alternator kill my battery? Will my alternator eventually charge up the battery again? Truck runs great.

 

You should always charge your battery with a charger .

it is possible to fry the alternator with a discharged battery.

From what I have seen myself a alternator overcharging does more harm to a battery then undercharging.

unless it is winter then your discharged battery can freeze.

 

So i trickle charged it overnight and i still get 10v. So this time i will pull it from the truck and drive to another advance auto parts for a retest. What a PITA.