91 harness in a 90

[Mafia Mustang]

I'm wondering If I use a wiring harness out of a 91 gt 5 speed and put it in a 90 gt 5 speed should that work fine ? I don't think there were any major changes that would hinder me.
I think if I used a 89 harness It would not work tho I heard.

 

[SFC_R0CK]

These are the years that match up to the dash harnesses.

87-89 I know are the same
90 not sure
91 was a stand alone year they are not compatibl with anything else
92-3 are the same.

if you have a donor car from a different year you will need all the harnesses and the ECU from the donor for it to work.

 

[Mafia Mustang]

I'm gettting alot of diffrent answers on this It's getting so confusing here is what one person said in a post before.

"1987-1988 Speed Density. All the speed density engine harnesses are interchangeable.
1989 Mass Air and No Air Bag. One year only harness. Only car with mass air and no air bag. The dash harness is the same from 87-89 on all models, but the engine harness is specific to the 89.
1990-1992.5 Mass Air with Air Bag. Fuel pump relay is under the drivers seat. The change here was made sometime in 92. All the dash harnesses for all models from 90-93 are interchangeable.
1992.5-1993 Mass Air with Air Bag. Fuel pump relay is in the engine compartment. All the dash harnesses for all models from 90-93 are interchangeable."

I think every one I have looked at has had a diffrent answer.

 

[jrichker]

Copied From bbunt302

Just for reference, here's a list of all the compatible years:

89 harness should work for 86-89 as long as you're using mass air.
90 harness will only work in a 90. (B/c of air bags and dual dash connectors)
91 through early 92 harnesses should be compatible (single dash connector, fuel pump relay under driver's seat)
Late 92 through 93 harnesses should be compatible (single dash connector, fuel pump relay under the hood)