Help!! Brand new alternator and battery..No Charge

I Own a 06 xrunner and I recently replaced the alternator and it ran fine for a couple of weeks...then last week the battery light popped up again and it died on me a the next day. Took the battery to autozone and they said the battery was bad so I purchased a brand new battery from them..put the new battery in and the battery light still didn't turn off...so it died on me again took the truck to autozone they charged the battery for free and did an alt and batt test...they said that the battery was good but the OEM alt that I purchased from Toyota a couple of weeks ago was bad...so I went to Toyota they gave me a brand new alt...put it in today and the light is still on...drove it around for a bit but they light was still on...took a multimeter to it 12.11 with the car off...12.04 with the key in the on position and 11.93 with the truck running....ANY HELP WOULD BE APPRECIATED....FYI the whole truck is stock no aftermarket anything on it

 

This seems to be a problen in the Alternator / Regulator ( the regulator is built into the alternator ). Looking at the prints the battery lamp is illuminated when there is a ground present downstream of the lamp.

What made you change the original alternator?
What were the indications then?
Was the battery charge light on then?
Is the battery light on when the truck is off, all the time or just when the truck is running?
The voltages you gave with the truck running seems like the alternator is not charging, but it could be getting dragged down by a high resistance short to ground.

I would first double triple check the battery post connections to ensure they are properly attached clean and tight. Same for the output wiring from the alternator for damage or grounding.

 

Outside chance dealer has a bad string of alternators. Went through this once on a Tercel commuter D/D I had about 10 years ago. Went through two bad new alternators ... never had another issue after the third one.

 

I once got three bad alternators in a row from one of the FLAPS...now I get them locally rebuilt.

Howard

 

Did you check the alt. fuse?

 

Where 's the Alt fuse?

 

THIS VIDEO WAS FOR A 1ST GEN TACOMA MY BAD!!
Its under the hood check your owners manual for the location of alt. fuse. I would send you a picture of it but im out of town driving around a f-250.

 

A FORD???? Such Sacrilege!!!

 

Only driving it cause they pay me to drive this pos.

 

EDIT - Sorry I missed the line you had your alternator replaced again at Toyota so that must be a new one. Disregard.

Was the replacement alternator a remanufactured one or new?

Sometimes reman's have problems. I had this issue years ago on the Corolla my wife drove before we got married. Her brake master cylinder started to go so I replaced it myself with a reman from Advanced Auto. Well in only a couple days the reamn went out as well (" Hon, my brakes are still soft"... "cant be i fixed it"... drive it and the pedal hit the floor ) - bad seals or a scored piston they didn't catch in the factory. After that we put in a Toyota OEM replacement from the dealer parts desk and never any more problems.

 

To prevent sulfation, I would keep my battery fully charged with an external battery charger until I found my vehicle's charging problem.

 

(Waiting and Hungry!)

 

Thanks for all the info...all the fuses were good...the only thing I can think of is the positive battery cable is bad...the only thing I could find I online was a entire battery harness for $700 bucks...is that correct just for the battery cable??

 

You can easily check the voltage loss across your positive or negative battery cables under high current conditions, like when starting the engine. Corrosion in terminal crimps to the cable or poor grounding could be a source of a voltage loss. Recrimping might help, especially if the problem is intermittent and there are multiple wires in the same terminal crimp. Cleaning ground connections may also help.

 

That's a bad "new" alternator or a melted charge wire or fuse between the alternator and the battery. Check the charge wire for continuity with a multi-meter. You should have at least 13.2-13.4 Volts w/ truck running.

 

No. That would be insane.

Did you check the wiring as we have suggested?

 

Like posted above, check all your wiring from alternator to battery for corrosion and tight connections. Check the continuity of the wires between the alt and battery with the multitester. Lastly, check for a loose or slipping serpentine belt.

 

OK, I got a dollar that says it's the alternator ....

 

2 bad ones in a weeks time ? Check all of your vehicles grounds.Clean them up and make sure you have metal on metal contact.Remove grounds, wire brush the shit out of them and the metal they connect to.All of them.Eliminate that first.Grounds drive sane people insane and insane people into the ground. I got a buck on bad ground.

 

You're on!!