1990mustanggt

I tried to do a search on this, but I couldn't find anything.

What might be some reasons that the alternator wouldn't charge. My first obvious guess was a bad one, but I replaced it and the new one isn't charging either. I'm going to try and run the wires down tonight to see if maybe one was cut. I could use any info that might help before I start.

Thanks Mike

ruger311

yeah i would track down the wires, if you installed a new one sounds like the wire that turns the regulator on and tells the alternator to charge isnt gettin any signal so best bet is to run the lines and see if something isnt connected or cut,

oh and another question, how do you like your 347 any track times, whats it putting down, whats your redline,,, i just finished mine and havent had time to get the tune or dyno numbers so just curious, thanks

1990mustanggt

I haven't taken it to a track or had it dynoed. The rear is still bone stock. I can't get any traction at all. It is fast as hell though.

1990mustanggt

Here is the problem. I finally ran it down. I just don't know how to fix it.
The diagram below shows a W/BK wire. It's a jumper of some sorts that runs the two plugs together. It's not getting fire for some reason. I can run a hot wire to it and the alternator works fine. The wierd thing is the alternator worked fine when I installed it on my buddies mustang. Can I just run a hot wire to it? I'm worried about burning the wires up.

[IMG]local://upfiles/10184/57F2EC30FE7A475EAB76396DD1C78762.gif[/IMG]

1990mustanggt

Any takers?

90GTRagtop

That makes it look like the internal regulator is blown. What you are doing is applying full voltage to the stator and the alternator is running at full output when you do that. The regulator's job is to apply a varying voltage to the stator to make the alternator charge just enough to maintain the proper output votage. Another thing that could do that is if there is no voltage on the Light Green/Red wire when the switch is on. There is a fuse in that circuit that can blow, and you will not get the activation charge for the stator. It's usually in the small fuses in the dash. Of course it could also be a problem with a broken wire, or the ignition switch.

Edit: Or the jumper itself could be bad.

1990mustanggt

The funny thing is that I can pull the alternator out of the car and install it in my buddies car and it works fine. I checked all the fuses in the fuse box and none are blown. Like I said, I ran a hot wire in the middle of the jumper wire and the alt. started working. I just don't understand it. It almost seems impossible. This thing is baffling. I even ran the wires down all the way to the firewall on the driver side of the car and found no broken wires. They all look to be ok. Is there a fuse located somewhere other then in the fuse box?

1990mustanggt

bump

90GTRagtop

Did you check for voltage on the Light Green/Red wire when the switch is on? It should have 12 volts. The wire can be broken inside the plastic casing and you won't see it. Get a DC voltage meter and check the voltage.

fordboyyfm

Check all fuses and fusible links. does the battery light come one? Does it prove out when you turn the key on?