[Steves LX]

O.K. guys I need some help!! I have a 89 LX and I hooked up a used wiring harness for the computer last night and upon completetion I tried to start the vehicle and all it did was crank it would not turn over. The harness I got was from a 1990 mustang. Everything was identical except there was a xtra plug down where the harness hooks up to the computer. My old harness didn't have that. There was a relay over by the Mass airflow plug. My old harness that was cut off. And over on the drivers side corner by the firewall where you would hook up to try to pull codes there was 2 plugs that plug into another harness one is black and the other grey. The black one went together fine but the gray one had like a lip on the inside of it and until I removed the lip I could not get it to hook up. I also noticed that my old one didn't have that lip inside of it and it had like 6 wires coming ou of it and the one I finally got hooked up only had 4 wires and there was a 5th one but it was cut. The only other goofy thing I noticed was the ground on the harness over where the silenoid is had a fuse holder on it. Black wire w/green stripe. Beyond that I dont know what could be wrong other than bad harness maybe. I thought maybe I hooked up my injectors wrong. I haven't tried flipping all the plugs over yet but I beleive they will only hook up one way. But like I said it just cranks and wont kick over or even try to kick over.

[OTreborO]

Originally Posted by Steves LX O.K. guys I need some help!! I have a 89 LX and I hooked up a used wiring harness for the computer last night and upon completetion I tried to start the vehicle and all it did was crank it would not turn over. The harness I got was from a 1990 mustang. Everything was identical except there was a xtra plug down where the harness hooks up to the computer. My old harness didn't have that. There was a relay over by the Mass airflow plug. My old harness that was cut off. And over on the drivers side corner by the firewall where you would hook up to try to pull codes there was 2 plugs that plug into another harness one is black and the other grey. The black one went together fine but the gray one had like a lip on the inside of it and until I removed the lip I could not get it to hook up. I also noticed that my old one didn't have that lip inside of it and it had like 6 wires coming ou of it and the one I finally got hooked up only had 4 wires and there was a 5th one but it was cut. The only other goofy thing I noticed was the ground on the harness over where the silenoid is had a fuse holder on it. Black wire w/green stripe. Beyond that I dont know what could be wrong other than bad harness maybe. I thought maybe I hooked up my injectors wrong. I haven't tried flipping all the plugs over yet but I beleive they will only hook up one way. But like I said it just cranks and wont kick over or even try to kick over.

You are screwed:

I did the same thing, and it will not work. There were major changes between 89 and 90. The dash wiring is all different. It will plug up the same, but it is not wired the same. For example when I turned on the blinker, the speedometer light would blink. I said WTF is going on. I did a lot of research, and I am afraid you will need the same harness as the rest of the car for it to work. Some folks will tell you that it will work, but trust me. I pulled a 90 motor and 90 LX dash and put it in a 89 car. Fuel pump wouldn't work, wipers wouldn't work, turn signals screwed up, horn would not work. Please find a entire wiring harness for the same year as your car. I think if you are ok as long as you are not working on 89/90 then you are screwed. You can exchange 1990-1993 harnesses from any car, but the 89 is a bastard child. I had a lot of folks tell me. They are all the same. Well, if they tell you that, then they have not done a 89/90 swap, or they are on METH. Please e-mail me if you need any help, or you can search for some of the articles I have posted. After I got the correct harness, I was on the road the next day. Good luck, and as I said e-mail me if you have any questions.

Robert

[OTreborO]

A few articles I posted on this

http://www.moddedmustangs.com/forums...wiring+harness

http://www.moddedmustangs.com/forums...ghlight=wiring

http://www.moddedmustangs.com/forums...ghlight=wiring


Or you can believe that all harness from Foxes will work. I did until I found out different

[99mustang232]

good times