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What is the easiest way to wire up a dohc 4.6 into a fox?

badcoupe50

New Member
Curious what everyone has done to wire up everything. Please post your do`s and don`ts . Everyone does it their own way, just looking for a wide variety of opinions.
 

modularf

Well-Known Member
badcoupe, I am working on tring to get a straight foward answer, I am in the process of wiring up our now..
 

FuturaGuy

Well-Known Member
Staff member
How to wire a 4.6 Mod Motor into a Fox:

Step 1: Mix a good stiff drink.

Seriously, I got the wiring diagrams for both the '98 donor car and the '88 receiver car. The '88 dash has a bundle of wires that goes thru the firewall on the driver's side to just about everything in the engine compartment. I opened up the bundle and TRACED EACH INDIVIDUAL WIRE. Using the '98 wiring diagram, I then matched each wire in the engine compartment harnesses to its counterpart in the '88 dash. I had to MAKE my own jumper harness that goes under the dash to connect about 30 wires that tie into the '98 harness on the passenger side. The local salvage yard was very helpful letting me cut the mating connectors out of a wrecked '97 Mustang and best of all, they didn't charge me for them. The best investment I made was a $15 ohmmeter from Radio Shack. I'd be lost without it.
 

kweb288

New Member
So just to clarify, you didnt use the WHOLE wiring harness from the doner car? only the engine wiring? and then you just spliced it into the old 88's harness and kept the original cluster and steering column?
 

d90212

New Member
That's pretty much how I did mine..right side of the harness going through the firewall is the eec harness...

Harness going though the left side of the harness or drivers side is all the accessory side... then you just match up the essentials like power ground...fuel...blah blah blah instruments...

If your motor has coil packs...don't forget that needs a power supply..

Best to get both vehicles evtm or wiring diagrams...can be found here helminc.com
 

FuturaGuy

Well-Known Member
Staff member
To answer kweb288's question, I only used the Modular wiring harnesses from the engine compartment and didn't get anything else from the donor car. There are 4 connectors on the Modular EEC harness on the passenger (right) side and they connect to lights, starter, ignition, fuel pump, instruments, A/C, and several other items. The corresponding wires on the '88 Fox Mustang go thru the firewall on the driver's (left) side, so that was the reason for fabricating a jumper harness.

The Foxes have the fuel pump relay in the rear of the car but the SN-95's with Modular engine have it behind the kick panel on the passenger side. Since the receiver car is a '79 with an '88 dash and never had fuel injection, I found it easiest just to take all the existing wiring out forward of the firewall, use '98 harnesses, and mate them to the '88 dash. I'm also using an '87 steering column and its light, directionals, and wiper switches.
 
One of the better answers with some detail actully included. When I do it I am going to document and post so no more get a wiring diagram and figure it out. I am going fox wiring with the 03 cobra pcm, pcm harness, and engine harness. Then if I need others or need less I will note. Then I plan to note the color coded wires and where an intersect is needed.
 

jaa55

Active Member
I have wiring diagrams complete for both 98 and 93 v8s. I could send them to anyone who needs them. Im starting my swap as well
 

88ragtop

New Member
Hi everyone Iam doing a mark viii engine swap and this so far is the best site I have found. The nut and bolt issues are the easy stuff, I too am looking for info on a 93 mark viii wiring swap to a 88 fox conv. So far this is the best site I have found, any hints or knowledge would be great. Can a cobra harness be switched for the mark viii harness?? I am also looking at whether the mak viii dash is a possible fit to the 88 fox, would be pretty cool. Thanks and I look forward to talkng with everyone. I BLEED FORD BLUE!!!
 

FuturaGuy

Well-Known Member
Staff member
8t9notch/88ragtop:

I have the '88 Mustang EVTM that has the wiring diagrams for the dash and the engine compartment. The '89 will be the same. If you want to send me a PM with your regular e-mail addresses, I can scan the EVTM and sent it to you.

I may not be able to help you much wiring a Mk VIII into your foxes. It depends on how much of the engine bay wiring you're going to keep and what you have to replace. My situation was a little different because I put an '88 dash into a '79 and replaced everything forward of the firewall, using '98 Mustang wiring for the Mod motor. If you're keeping most of the '88/'89 wiring, then you have to connect what to need for the Mk VIII to the rest of your wiring.

If you can't get the wiring diagram for the Mk VIII, try a Ford or Mercury dealer. They have everything on CD and if you cultivate the service manager (sometimes a 6-pack of his favorite beer will help), he'll either print out what you need or let you burn a copy of the CD.

When you've figured everything out, WRITE IT DOWN! Otherwise, you won't remember what you did and no one will ever be able to work on the car again.
 
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