[The__Dude]

I recently got a new battery the previous one was four years old and was having a tough time in the recent cold. I put my new volt meter on the new battery and it seems to remain at 12.5v weather the truck is running or not at idle or at 2500rpm. I started the truck then disconected the battery the truck still ran so does that mean the alternator is ok? What tells the alternator to charge the battery (voltage regulator) Where is this and how do I check it?

Everything could be fine as I have made several trips and not killed the new battery but I was testing out my new meter and I didn't get the readings I though I should ie 14 volts when running.

The fuses looked ok and the connections to the alternator also looked ok.

thanks
Just trying to avoid pulling the alternator and getting it checked since there is a foot of snow right now.

 

[The__Dude]

96 v6 115k

 

[The__Dude]

The parts stores say its bad and they don't sell replacement parts?

 

[ShowStop]

I started the truck then disconected the battery the truck still ran so does that mean the alternator is ok? What tells the alternator to charge the battery (voltage regulator) Where is this and how do I check it?

Cant help you with the charging circuit, but if you can disconnect the battery and the engine still runs, then your alternator is working.

 

[The__Dude]

That is what I thought, since I was able to turn on the headlights although once I fired up the off road lights the motor died (with batt disconected).

 

[The__Dude]

Picked one up from the junk yard for 65 bucks. I did finally find a voltage regulator for sale but it cost over a hundred bucks. I now have a trail spare altenator that puts out 12.5 volts instead of 14.4 I guess it could get me home I'll keep it with my spare starter (auto tranny).

 

[tanKoma]

alternators are expected to fail at 100000+ miles

 

[ShowStop]

alternators are expected to fail at 100000+ miles

225k miles and still kicking here...

 

[Dick Foster]

The voltage should be higher than 12.5v at a lower RPM than that and no real heavy load on it. That is unless someone has rewound the alternator for more current. In that case it will take more RPM to get the voltage up. There is an 80amp fuse in the underhood fuse box that is between the alternator and battery. Make sure that is OK. The most common alternator problem is worn brushes. The next is a blown diode or two in the diode pack, then comes the regulator. All of them are easy to swap. You should be able to get some brushes at Toyota or off the web somewhere. Nippon Denso alternators are very common so parts are not hard to find. You may want to take a look in your local yellow pages for an alternator/starter repair shop, those are usually easy to find and they should be able to help you out with parts or service. Changing parts in an alternator is straight forward and easy. The only hard part of the process is the R&R of the alternator itself.