My alternator is only putting out 12v (while in the vehicle). Put in a new alternator and voltage regulator about 6 months ago, other than having to get an adapter for the alternator wiring I have had no problems at all. Until a few days ago when the top bracket on the alternator broke, I replaced bracket and noticed that the bottom pivot point was sloppy (alternator could twist about 10 degrees) compensated for this by replacing pivot bolt with an oversized one no more twist. Now my alternator is only putting out 12v (rather than 14.6v) the alternator terminals were not in such a position as to allow contact with anything. I replaced my battery, got nice tension on the alternator belt. Now Since the alt. will still only put out 12v, I have come to the conclusion that when the bracket broke one of two things occured. A wiring to alt/voltage reg. was some how damaged or B bearing inside the alt. was damaged due to the belt not being aligned properly when the twist occured. I have not been able to take the alt. in to have it tested out of the vehicle yet due to the holiday, that is my next step. Now alt test bad on bench, no prob replace alt and go on. However if on the bench it works properly where do I go from there?

 

even though I got zero responses, I am still dealing with charging problems. Alternator, voltage regulator and battery are all good. just replaced battery cables and connectors, still getting 12.1 volts at battery but getting 13.6 volts off batt terminal on alternator. Temp solution, disconect wire from batt terminal and run 10 guage wire directly to positive terminal of battery. So now I am charging. With negotive battery terminal disconected, I put voltage meter on neg. terminal and neg. cable getting 6 volts with no power on. So I have a short, its not in any fused circut ( I pulled fuses one at a time and still got 6 volts ) I assume there is still power to batt wire for alt. and it is grounding somewhere. New problem How to locate this short or at least where to begin, can't find it in any obvious place.

 

Yeah, sorry...I'm pretty ignorant when it comes to electrical stuff. I've been lucky in that area and haven't had the kind of issues to force me into learning how it all works and how to trouble shoot it.

 

Explain this adapter you put on your alternator. I recently completed a GM alt conversion so I learned the charge system pretty good so maybe I can help.

 

Was the wire you disconnected from the battery a white 10 gauge wire? If so you probably took power off several other things. On my 83 I had that wire unhooked and I lost power to my dash lights among several other things. So hook it back up and cap off the end that used to connect to the alternator.

I don't remember seeing this thread or I would have posted earlier. Also with you posting on Christmas Eve a lot of people were busy with the holidays so cut us a little slack.

 

First sorry to all, I was frustrated at the charging system and complained about folks not responding. I'm a 50 year old man I know better. Now on to my truck. First the adapter I'm attaching two pics the first one is like my original alternator (note different plug and letter designation) the E terminal and the F terminal are reversed from the second one. The adapter simply reverses these two terminals so that my wiring does indeed get to the correct terminal. Second I disconnected the wire on the B terminal at the back of the alternator, other than being disconnected from the alternator itself it is still intact and in its original position. I believe my short may be in this wire, does anyone have a really good wiring diagram for one of these.
I have the one from my haynes manual, but it doesn't really reflect what I'm seeing under here. Also remember the chinook camper shell was added which changes some of the wiring.

 

Idk about a 76 but I'm pretty sure Autozone would have some kind of wiring diagram. You have make a free account with them and login to get access to them though. I also have a thread to download a FSM for an 83 but idk how useful It would be.

 

Well most of my problems have been solved, I just moved to tucson AZ and took a job driving a tow truck. One of the shop mechanics is a toyota guy, he has more answers than chilton.

 

There are two alternator setups for Toyota pickups (1) with 5 wires going to the external regulator and (2) with 6 wires going to the external regulator. The variations can be determined one of two ways:
(1) Find your external regulator (on the driver side fender wall near the power steering reservoir) and count the number of wires going to it.
(2) The green vs black plug on the alternator. I BELIEVE that the alternators with the green plug have a 6 wire regulator and the alternators with the black plug (like the one you have shown above) have a 5 wire regulator. I personally just bought a new alternator for my rebuild and I bought the black plug and I confirmed that the voltage regulator is a 5 wire on my truck.

In addition, the Green vs Black plugs are different patterns - The wiring harness for a green plug alternator will not plug into a black plug alternator and vice versa. I BELIEVE that the difference in 5 or 6 wire also depends on whether or not the truck has AC, but I'm not sure of that. When you replace the alternator it is suggested that you replace the voltage regulator as well - that could be causing your charging issue.