alternator not charging

so i have a 2000 tacoma with the 2.7 and we bought a new alternator after the old one going out and leaving us stranded. the truck ran fine before no hickups but not we have a new alternator and we put it in and it’s not charging took it to autozone and it passed the test. the alternator fuse looks good i’m at a loss right now any help would be good

 

Did you put a meter on that fuse to verify continuity? You can't always tell just by looks.

 

yes sir we did

 

Tell more about this. Did autozone test it while it was in the truck?

How do you know it isn't charging? Is it the Alt light on the dash?

What is the voltage reading at the battery when everything is hooked up and the truck is running?

 

we took the alternator out of the truck after We installed it and took it to AutoZone and we know it’s not charging because we put a voltage meter on the battery terminals well the truck is running and the voltage is reading about 11.9 to 11.7 and keeps draining while the truck is running

 

Yeah, you need to know how many volts are coming to the battery when it's running. That will tell you if the voltage regulator, which is usually inside the alternator, is working properly. Then, of course, check and clean all connections and make sure the battery is fresh and able to accept a charge. But basically, if those three elements are working properly - battery, alternator and regulator, and cables and connections, then the battery should charge.

 

OK I will go clean all connections including the motor ground and we will see what happens thank you

 

Is alt a new or reman'd one purchased from Autozone?

 

it’s a refurbished one that we got from a local store

 

I asked this earlier but you may have missed it. Is the dash alternator light on?

Do you have another way to charge up your battery. Perhaps in another vehicle or a dedicated battery charger? Get the battery fully charged, then have autozone test the entire system in the vehicle with it running. They can also do a quick charge on the battery. This will eliminate the possibility that you don't also have a bad battery.

 

I do not have a dash alternator light on but I do have a dedicated battery trickle charger and we fully charge the battery after each test and the truck will not make it to AutoZone on the battery itself

 

What is the voltage reading at the battery when you remove it from the trickle charger?

Unless the bulb is burned out, the lack of a dash light would indicate that the alt is charging which agrees with what autozone told you about the alt.

 

it’s reading 12.6 V when I remove it from the trickle charger and when I turn the key to turn on the truck the alternator light does not turn on at all I don’t know if the truck has an alternator light

 

With the engine running you should be getting between 13.8 and 14.2 volts at the battery - roughly. If it's less than that after you've cleaned all the connections and contacts then it's highly likely the internal voltage regulator in the alternator is not putting out the correct voltage. A nominally 12 volt battery needs to have about 14 volts going into it in order to charge.

 

At this point it might be worthwhile to verify the battery is good. How old is it? Maybe remove it from the truck and take it to autozone. They will have a way to test it under load.

 

Don't forget, he's already had the alt tested at autozone.

 

the battery is brand new

 

So, a new (reman'd) alt that tests good outside of the truck, that does not turn on the alternator dash light, yet shows lest than 12 volts at the battery while running. All with a brand new battery. Sorry, this does not add up.

I know you started this by asking if the truck's system (not the alt or the battery) could be somehow causing this, but I don't see how.

My guess still is that the battery is not accepting the charge coming from the alt.

 

Have you checked the Alt-S fuse 7.5 amp?
If its good you need to go down to the alternator and check for power.
The big white wire and small white wires should have power all the time, the small red wire should have power with the key on, and if you ground the yellow wire with the key on the battery light should turn on in the dash.

 

there is something "basic" here that isnt right and having said that lets start from the beginning.

inside the engine compartment fuse/relay box there is a large bolt in fuse (120 amp) check this first, then the 7.5 ATC blade fuse. If these 2 are good turn the key to the on position, do not try to start the truck, ALL of the warning lights should illuminate in the dash for a second or 2. This is a built in "bulb check" feature. Does the Red Battery symbol illuminate?
If not that needs to be fixed first.

If the light does illuminate then the alternator HAS to be grounded to the motor and the motor to the battery. With your volt / ohm meter set the dial to ohms. With one probe touch the alternator case with one lead and the negative post with the other. It should read 0 or close to 0 ohms resistance. You can also take a piece of wire and touch the alternator case and ground the alternator to the negative post of the battery. If she starts charging then you have to figure out why the alternator isnt grounded. This would be kind of tough since it is bolted to the engine... I have seen this on other vehicles so Toyota shouldnt be any different.