Stock 1993 charging issue at idle

The stock alternators were never very good. Sounds like it’s time to do the 130amp alternator upgrade (many kits out there for this) as it’s a very common upgrade.

Once you go 3g you never go back.

I’m not saying it’s the issue but have you replaced the alternator wiring harness? I only say this as the wires can corrode internally (turn green) and will cause all kinds of issues. To test this remove the connection at the alternator that has the black/orange wires and where they attach at the starter solenoid and ohm them. They should be near zero ohms as short as they are. If you get a high resistance my guess would be they need to be replaced. Someone correct me here if I’m wrong.

This is a good thread on trouble shooting the 2G and 3G alternators specifically jrichker’s post which is the second post in the thread:


If you want to keep the car stock then Ron Francis makes a new harness but you have to get the headlight harness as the alternator wiring is in this harness. They also make one for the 3G/4G alternator. Neither is cheap ($200+) but it retains the factory look.

If you don’t care about it being factory stock then you could look at replacing the fusible link and the two black/orange wires and see if that corrects the issue. This would be a little work but you could do it outside of the headlight harness to see if it is the issue.

Installing a 3G is what I would and have done but neither of my cars are stock and I will never have a completely stock vehicle. There is a thread on here for installing a 3G but it comes back as a broken link. I’m currently in Germany so maybe it’s on my end but I messaged Noobz to take a look.


Whatever you do install 4 ga ground wires from the battery to frame and from frame to the block of the motor. If you do not have adequate grounding then the higher amp alternator will not work as well.

I gotta agree with aero either way you should upgrade your ground wires, Ford's are known for week grounds.