1993 Mustang 5.0 Engine Swap

by Roger Henson
(Oklahoma city)

1993 Mustang 5.0 Engine Swap Question:

I have a 1993 Ford Mustang coupe with a 4 banger (4 cylinder) and AOD (automatic overdrive transmission).

I pulled the old 4 cylinder motor and tranny out and installed a 5.0, AOD out of a 1989 Mustang hatchback.

I got the ecu wiring harness with the 1989 engine and transmission and I pulled the ecu wiring harness out of the 93.

What do i need to hook up the 1989 Mustang harness? Or is there another direction I need to go?

Suggestion:

First off, I'm assuming that you already have ironed out the details for motor mounts, driveshaft, fuel lines, radiator, map sensor swap and of course mating the basic starting circuit to the new engine.

So we'll strictly address the engine and transmission wiring part of your 1993 Mustang 5.0 Engine Swap.

I can't give you a definitive answer as to whether the harness swap will be exact, since Ford loves to change vendors, and try to keep you attached to your local dealership service department, but here's how to approach it.

The first thing you need is a copy of the ECU wiring diagrams for both, the 1989 and 1993 Mustangs. While the 1989 to 1991 harnesses are virtually identical, the 1993 is not. For instance, the wiring colors for the map/baro sensors have only one of the three wire colors in common. But that just means a little more homework!

The good news, is that you are working with two harnesses and ECU's from an automatic car.

Steps:

1. Trace all color codes from the stock 1993 ECU outputs, to their respective parts.

2. Verify, using the 1989 wiring diagram, any changes, due to the model year differences that may exist and label/change them to match. I've included a pinout diagram for the 1991-1993 V8 ECU for reference.

3. Check the lengths of the wires for fit. What I like to do, if the color has changed and/or the length is different, is to splice the new wires somewhere before the connectors, so that you can tell at a glance looking at wire colors, which one(s) you have.

4. Once you have verified the wires and where they go, it's time to check connectors. The important things to look for, on your 1993 Mustang 5.0 Engine Swap are pin location and grounds.

I've done several re-wiring jobs on various Fords and even one year to the next, which externally look identical, can have connectors with reversed pin locations and of course different colors.

5. Transmission members should fit, but if you are going from single exhaust, like a typical 4 cylinder to a full dual exhaust, you may want to use a 1993 V8 double hump crossmember, to make clearance for the other exhaust pipe.

If you need further explanations, go to the comments section below and we can add to this thread.

Good Luck!
B.

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