harness prob. pleeese help

[jamrok55]

i have a 90 4cyl im swapping to an 8.the harness coming out of the firewall by the brake booster has only 1 brown plug unlike the grey and black all the other years have.but i only see the brown plug on 91 stangs.im a little confused.what year engine harness do i need?from what i understand the 4 cyl is unmolested but people are saying 91 is the only year with the single brown plug please help...

 

[SFC_R0CK]

According to stykthyn those are the ECU harnesses that match up with the same dash harness.

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.

 

[cheese_05_70]

I did the 4 cyl swap and i was always under the assumption that they changed it after 90. I have a 90 harness on mine the only problem i have is that my horn dont work.

 

[SFC_R0CK]

Check your horn fuse and your horn relay, do you know if the horn worked before the swap?