The mechanic that my folks have done business with in the last twelve years has diagnosed a bad ECU in the mustang but is unable to find good condition parts from any of the nearby salvage yards. The parts manufacturer he uses doesn't carry it due to the ECU being discontinued. I found refurbished/remanufactured ECUs on Advance Auto, but the mechanic said that he had very bad testimonies of reconditioned parts from those stores. On eBay, the part varies from 300 to 700 dollars, but I don't know if there's any reassurance that the part will continue to run like six months to a year in from replacing it and will fail.

The part in question is the Cardone 785610. On it, it has the numbers E9ZF12A650BA, A9M.

For anyone that has had a bad ECU in the past, where did you look to find the part? I also want reassurance that the part will continue to run instead of failing like a year later.

 

What's wrong with the car that the ECU is diagnosed bad? Not that I doubt your mechanic, but more info's always good...

Regarding reassurance... nope. I'm sorry, but the reality is the computers are all from '92-ish. That's around 30 years old. Stuff's gonna break, and there ain't no new computers. All of them are going to be refurbs, because there's not enough demand for them. Most people would just toss the car and get a newer one. Good on you trying to save yours! I'm sure it appreciates that.

So you get what you get, experience be hanged, because there's no real choice. And you hope. Perhaps your mechanic's had a bad run of Explorer or Camaro or whatever other, but hasn't had but the one Mustang computer to deal with, and the Advance one for the Mustang is just peachy. Or it's not. But for the 100-200 bucks (depending on the car's engine and transmission needs) that sounds like you do it regardless of your mechanic's reticence. It's got a year swap warranty on it and that's not terrible. And maybe you do it yourself, it's 'just' a computer swap. The EEC-IV doesn't have to be programmed or such to the car, it's a literal plug and play box in that car. Or so I remember. Maybe I'm wrong, and someone will tell me, but I don't think so. If the computer's the correct one, it'll just work.. The hardest part is getting to it to swap it. Battery disconnected, of course. And here's that:

And the guy can repair them:

Another example of bad ECU test and and how to fix:

Kit for that, if you wanted to tackle it yourself:
https://www.ebay.com/itm/89-93-Ford-...-/352446543989

So the real deal is get a proper computer for your car, however you can, get it running, then send off the old computer and get it repaired/repair it yourself if you dare. This will be your ongoing swap item from here on out on that car: Computer goes bad, swap the refurb, send off/fix bad one, repeat. And there's your semi-reassurance, as best you're gonna get at this point.

You can also swap it for a Holley EFI or something, but that seems extreme. So of course you're going to do that, right?

I hope that is of some help, and good luck!