New wiring harness

[gt90_hatch]

So i just got my new wiring harness for my 1990 mustang gt and i was wondering what all do i need to take out to get to the computer all the rest is not going to be bad i was just asking before i dive in thought i might get some advice from someone who has been down this road.
Thanks

[88mouse]

I usually take the blower motor box out. It make is alote easier to get the harness through the firewall.

I think it two 8mm bolts (some are 7mm) and a 12mm in behind the glove box.

[chavist93]

Did you get the pm I sent about the harness you bought? That is plug and play for 93 only and some late 92's. It's not going to work for your 90 without some major rewiring.

[gt90_hatch]

Did you get the pm I sent about the harness you bought? That is plug and play for 93 only and some late 92's. It's not going to work for your 90 without some major rewiring.

no i didnt get it i wishe i would have i dont really know what im going to do now but thanks for the heads up if i would have looked you would have saved me some money.

[nitrostangracin]

Did you get the pm I sent about the harness you bought? That is plug and play for 93 only and some late 92's. It's not going to work for your 90 without some major rewiring.

I don't know why you are saying this at all. I have personally installed the same harness in my 88 when I did my Mass Air Conversion and it worked no problem.

Even according to Ford it works on 89-93 5.0 Fox body Mustangs. I know guys that have even used it on 94-95 cars that did an EEC IV Conversion.

Weren't you intersted in buying this from me?

[chavist93]

Weren't you intersted in buying this from me?

Yes, for a 93 4cyl conversion

Late 92-93 used the harness that the OP bought from you. This harness has the fuel pump relay included in the harness like late 92-93 did. It gets mounted under the MAF meter on those years. All other years were under the drivers seat.

91- early 92 use the same harness

90 is a one year only harness

89 is a one year only harness

87-88 are the same

[Notch93]

It's not going to work for your 90 without some major rewiring.

It has been done way to many times, to say it won't work. My friend just used the same harness in his 96 V6-V8 (302) swap.

Here is the manual in PDF form, for the OP.

http://www.fordfuelinjection.com/files/M-12071-C302.pdf

[cobra_4]

It has been done way to many times, to say it won't work. My friend just used the same harness in his 96 V6-V8 (302) swap.

Here is the manual in PDF form, for the OP.

http://www.fordfuelinjection.com/files/M-12071-C302.pdf

Now all we need to do the install is about a case of beer:beerchug:

[Wayne's 88 GT]

Now all we need to do the install is about a case of beer:beerchug:

AND somebody else to do the install :lol1::lol1::lol1: man I have a headache just reading the instructions......looks like mine will stay speed density forever!

[chavist93]

It has been done way to many times, to say it won't work. My friend just used the same harness in his 96 V6-V8 (302) swap.

Here is the manual in PDF form, for the OP.

http://www.fordfuelinjection.com/files/M-12071-C302.pdf

Oh I'm not saying it cant be done. That main purpose of that harness is to do 5.0 EFI conversions. Just saying that harness is only plug and play for late 92 - 93 cars. When a factory 90 harness is so easy to find and will be plug and play for him why bother with the headaches of using another harness.

[Notch93]

Oh I'm not saying it cant be done. Just saying that harness is only plug and play for late 92 - 93 cars. When a factory 90 harness is so easy to find and will be plug and play for him why bother with the headaches of using another harness.

So in you other post, you said the only difference was the location of the fuel pump relay. So whats so hard having/putting it under the hood (easier to access) then under the seat?

[chavist93]

So in you other post, you said the only difference was the location of the fuel pump relay. So whats so hard having/putting it under the hood (easier to access) then under the seat?

It's not just the physical location of the relay, on cars with the relay under the seat the wiring for the relay is not part of the main engine hanress. There is another difference I will show below with pics. 87-90 uses one black and one grey connector to connect to the vehicles dash harness. This connector is located just behind the drivers side strut tower. 91-93 uses one large brownish red connector.

1990 harness
http://i2.photobucket.com/albums/y6/chavist93/img2598hm5.jpg

Late 92 -83 harness aka M-12071-C302
http://i2.photobucket.com/albums/y6/chavist93/img1183xg1.jpg

[gt90_hatch]

So does any one know what all has to be done to make this one work cause i talked to someone who said something about my car having two plugs by the brake booster for the fuel pump relay and the one i have only has one so i am just tying to figure out what to do.:brightidea::brightidea:

[chavist93]

So does any one know what all has to be done to make this one work cause i talked to someone who said something about my car having two plugs by the brake booster for the fuel pump relay and the one i have only has one so i am just tying to figure out what to do.:brightidea::brightidea:

The plugs by the brake booster is where it connects to the dash harness. If your car has one large reddish brown connector like the 2nd pic I posted then that is a plus. The replacement harness you have should be the same. Maybe someone else here can help you figure out how to rewire it for the fuel pump relay. I'm not of any help on that part.

[gt90_hatch]

The plugs by the brake booster is where it connects to the dash harness. If your car has one large reddish brown connector like the 2nd pic I posted then that is a plus. The replacement harness you have should be the same. Maybe someone else here can help you figure out how to rewire it for the fuel pump relay. I'm not of any help on that part.

Well thanks for the info so far i will just have to figure it out from here.

[kdawgg11]

90gt hatch I did my 87 about a year ago and it was not as hard as I thought it would be actually it was pretty simple it was plug and play except for one wire I had to slice not sure what it was but I use the old wire to work. So just take your time and let me know how it went good luck and if you need any questions let me know I will do what I can to help

[gt90_hatch]

90gt hatch I did my 87 about a year ago and it was not as hard as I thought it would be actually it was pretty simple it was plug and play except for one wire I had to slice not sure what it was but I use the old wire to work. So just take your time and let me know how it went good luck and if you need any questions let me know I will do what I can to help

Thanks :thumbsup1: