Underdash Wiring

Underdash Wiring

Underdash Wiring Installation

After seriously procrastinating over the Independence Day weekend, I dove head-first into working on the underdash wiring yesterday.  And while it doesn’t look like much, I’ve made some serious progress.  Some folks would probably thumb their noses at the idea that installing underdash wiring could take more than a day.  They don’t know me.  I’m methodical (and therefore slow), but I’d rather do the job once and do it right.

Last weekend I spent hours stringing out the Mustang, setting the toe-in because it always wanted to steer itself into the shelves.  Three hours later I had the car tracking dead straight with 1/8″ of toe— a big win for me, but not what you could call progress.

I’ve had the wiring laid out inside the dash for several months, but that’s as far as I’d gotten.  I took a ton of pictures when I pulled the original harness out.  But as I’ve said before, no matter how many pictures you take, it’ll never be enough.  I spent most of the day yesterday looking at pictures and then looking in the Electrical Assembly Manual in occasionally futile attempts to figure out how it’s supposed to be.

How did Ford do it?

That’s been the big question: how did the factory do it?  Engineers spent hours designing the car, and they probably had good reasons for doing things the way they did them.  I’m all for improvising when it’s necessary, but if I can put something back exactly how it’s supposed to be, I’d rather do that.  On the Mustang that’s relatively easy to figure out because all the factory assembly manuals are available.  Of course, just because the engineers wanted things installed a certain way doesn’t mean Dick Doofus did it that way. I read a quote once to which I refer back when my perfectionism starts creeping in, which I’ll paraphrase here:

These cars were assembled in dimly lit conditions by guys who were nursing a hang-over, trying to just make it to the end of the day.  Screws were put in cock-eyed, obscenities were spelled out in wire fed welders on the sheet metal, parts were broken when they were assembled.  All that’s to say, “Do your best, but do it with a little apathy.”

So I’m always trying to balance the way Ford DID it on my car with how Ford wanted it done.  In the case of the underdash wiring, they put clips in different places, and used fewer of them, than specified.  They routed wires on the wrong side of the wiper motor, placing them in danger of being chafed by the linkage.  Some of the parts stores sell a harness guard to protect the loom.  I don’t know if Ford was still using it when my car was assembled, but mine didn’t have one.

Is it worth it?

No one will ever see the wiring but me, so it’s probably not worth fussing over.  If a guy’s enough of a dick to roll up under the dash at a car show, he deserves a dope slap.  But if I only did things that were “worth it,” I wouldn’t be restoring this car in the first place.  Ultimately I feel like some of the value here will accrue to the next owner.  He (or she) will be able to look at the service manual and see something that matches the pictures.  Few things are more frustrating than trying to reverse-engineer someone else’s handiwork.

Where I stand now…

I’ve got the dash switches in, and I’ve connected the tail light harness to the underdash harness.  I’ve also connected the underdash harness to the engine compartment wiring, which is basically complete.  I loomed up the Pertronix wires with the coil wires for a cleaner installation, and I’ve also connected most of the Rally-Pac wires in the engine compartment and under the dash.  I’ve got the reverse wires connected down at the transmission.  That leaves me with a few odds-and-ends to tie up today, most of which surround the air conditioning system.  Depending on how those go, I may tackle the instrument cluster rebuild today.  I’m missing some wiring clips, so I can’t install the cluster yet, but it’ll be nice to check it off my list.  Onward!

1 thought on “Underdash Wiring”

  1. Andrew, you’re moving down the home stretch, and a commendable task it’s been to bring “An unknown to a known”, and nobody can take that away from you. Kudos to you!!

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