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71 versus 71 wiring harness
Qustion :
Are 71 and 72 wiring harnesses of mach 1 interchangeable ?
No, not unless you change all of the one year to all of the other.

For the most part, they are the same, but there are some small differences, mostly in some of the connectors (number of pins).

Let me check your shorts!

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[Image: oldfart.png]
midlife;128029 Wrote:No, not unless you change all of the one year to all of the other.

For the most part, they are the same, but there are some small differences, mostly in some of the connectors (number of pins).

I cleaned the fise box contacts and the 72 wiring harness is functioning perfectly in my 71 - so in this respect they are interchangeable.
You are right that some connectors are different, but the basic stucture of these two harnesses is the same.
I have looked around for a new '71-'73 wiring harness with no luck. But everyone sells a harness for 65-66, 67-68, or a 69-70 harness. Other than the '71-73 being a longer car, us there any reason why I shouldn't/wouldn't be able to use an earlier year harness? I like the idea of "brand new stuff" vs a 40 year old harness.
there is also more to wire harnesses depending on year you need to match the options your car had. a 71 convertible harness would not work well in a 71 mach 1 for the engine bay. behind the dash if you had a A/C car there are differences from a standard heater car.

It would be difficult to find a replacement for exactly your car, so the best bet is picking up a donor harness then using that to make repairs to your existing harness or sending it to mildlife for refurbishing.

I used a 1973 Convertible as a donor for my early mach 1 1972 A/C harness. the end connectors are the same, things like sockets for lights and sensors for brake pressure. The wires them selves are different colors but have the same function, a connection wire in 1972 might be black with pink marking, and on the 73 might be yellow with a red marking.

functionally the connector might be the same but stick out like a sore thumb if somebody later needs to make electrical repairs.
some sockets are very different but can be modified to work on the early cars. example a 1973 sport lights grill used a 3 pin connector because the sport grille worked as turn signals and running lights. on 1971 1972 cars there was separate lower turn signal lights and the sport grille lights were running lights when the headlights were turned on. it is possible to rip out the 3rd lead from the 1973 lights and rebuild them to work with the 1971,2 cars. you have to at least make sure if you have a gauges car that you do not use a donor from an idiot lights car because the connections will be different.

the biggest change from 71 to 72 was in 71 the convenience wiring group was integrated into the main harness, this made dealer installs easy for accessories that a car was not equipped with from the factory. for 1972 ford took the convenience wiring out of the main harness and created a daughter wire harness that plugged into the main harness in a few places to allow accessories to be installed. But there was a Cut of point for this change in August 1971 for 72 model year. so early 72s have the integrated 71 harness. Basically it makes things a bigger pain when searching for a harness. also even early 72s had a small change to the harness in removing the wiring for the map light. for a 71 if you want to add a map light you just plug it in. for 72 even early 72 the map light connection was on a daughter harness. so unless you hack into the fuse box or find the map light harness you have no way of hooking up the maplight OEM style. here is the kicker,,, they took out the maplight connector but left the footwell lights connectors which tied into the maplight. no wonder ford was losing money with all the different wire harnesses.

The best is saving your original harness and then repairing or restoring it. sometimes this is not possible due to rodent or fire damage but it is the best bet.

rebuilding the harness is time consuming after unwrapping the wiring you will find the wires are molded into cast plastic/rubber holders and the wiring clips are a separate strip held on the wires by the covering wrap.

I ended up cutting the plastic molded pieces which allowed me to replace entire strands of wire back to a problem area or allowed me to splice in accessories i needed. after the wire was soldered and heat shrink protected i would lay the wire back through the plastic/rubber holders and reglue them shut later i would come back with the clip strip and recover with black wire wrap. took me about 2 days of work to rebuild my harness. I even went as far and opening up the molded connectors and running new correct color marked wire for a few runs. you always find, damage broken wires or areas where somebody hacked the harness to install something.
After reading this post it got me wondering.

Would it be possible to change our fuse box for a new modern style fuse box?

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73 Convertible 302-4v-3spd yellow /white int

08 Bullitt 4.6-5 spd black/black int

All I ask is a chance to prove that money can't make me happy
Anything's possible. But what are you going to do with the green connector on the back of the fuse box that mates to the headlight harness?

There's nothing wrong with the glass fuses (except removing them if you don't have the right tool). When changing over an existing harness to the modern fuses, don't go over the existing fuse limit for that size wire; it is the wire gauge that determines the size of the fuse. Many people want to add for circuits, but you really shouldn't due to possible overloading of the incoming wires.

Let me check your shorts!

[Image: Flamicon2.jpg]

[Image: oldfart.png]
sure guys have installed the painless harness, it is a TON of work compared to refreshing the original harness. refreshing isn't fun either but at least everything fits when your done. with aftermarket you have to make a ton of single connectors to plug into the different tabs. Really repairing your original harness is easier.

what i hate about the stock fuse box is when you hit a speed bump or a nasty pot hole sometimes a fuse pops loose or over time a fuse gets corrosion and you get intermittent contact.
But what should you do if you convert to EFI? Not to start a Windsor vs Cleveland debate, but... One option is to go the supercharged Windsor route. My '95 GT had a 393w with an S-trim (Vortech) 10lbs of boost and made 550 RWHP before 5500rpm. And that was under cammed because it needed to pass California emissions.
So, with more motor (408-427), little more cam, better heads, little more throttle body and even the same boost, I can get at least 600rwhp, extremely streetable and will probably still pass emissions if it needed to.
With the wiring harness for the 5.0L engine, should I also upgrade the rest if the wiring?
well you could modify the original harness as needed then with the EFI you would have a secondary harness as needed for the sensors.

the problem is replacing the entire harness you have a lot difficulties. that is replacing everything, from engine to taillight and figuring out how to connect the 71 electrical switches and gauges etc to a universal wire harness.
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