I have had some alternator issues lately. I took my car in to have some minor work done and got it back with two alternator wires disconnected. I am not sure what happened, but I now need help with what wires should go where. The alternator that I have has 5 pins. There are four wires to connect, but there has been some mods done in this harness by the PO. I now have the alternator charging, but the alt light comes is on very dimly at low RPMs and brighter at higher RPMs. My guess is something is not wired up correctly. Can anyone shed some light on what pins go where. The alternator is a Duralast.

Thanks,

U.C.

 

http://www.themustangshop.com/69MUST.ZIP

 

Thanks. This helps a bunch. The big problem now is tracing wires, cuz none of my colors match this chart.[:@]

Now, does anyone know what posts do what on this alternator? There do not seem to be any markings on it except one post is larger than the others, which I know is the charging hot lead. It looks like I need two leads going to the voltage regulator, one for the charging lead, and a ground. I just do not know what pins do what. Guess I can stop by AutoZone and see if they can help.

Any ideas why the ALT light would not light when the altenator is unplugged, but lights when the altenator is plugged in and charging? It gets brighter as the RPMs get higher. Need a buddy to help look at the voltage to see if they increase or decrease with RPM. Still the light does not work very well if it is not lit when the darn thing is unplugged.

 

Hey Cow Poke. See if this helps.

 

I saw that image during my searching, but I have four wires. That one only shows connecting three. I am guess here, but STA stands for starter?Not sure which one to leave out. Plus, I think it was titled 65-66 Mustang config. I was not sure if the 69 was the same or different.

 

OK, then see if this pic helps. It's one that one of our members posted a few years ago, and it's hiis 69 351. See that little red wire that isn't attached?

 

That's a great picture of the setup. here as well 2 cables not hooked up as in your setup.

it's not too uncommon to have the alt light dimly on when the engine idles very low (not making too much charge when idling). Could be a loose belt or something.
What concerns me is that the alt light goes brighter once you rev it up. that for me seems like the car is sucking more power than the alternator supplies.

make sure the belts are ok, as well as that the alternator is grounded properly. You can check if the issue is gone if you pull a temporary cable from battery- to alternator housing. as well make sure you have the engine properly grounded (strap).

Let us know if any of those temporary fixes help. If you have a multimeter or voltage meter. what's the voltage over battery+ to battery- when car is off. and what does it read when car is running ?

Kalli