Hey out there. I got a 75 f150 with some wiring issues. I own a Haynes manual with the schematics for it but they dont match what I've been looking at for the past week. Some things are wired as they should be or mostly and some things are completely whack. Hell, some things are not even wired period. Should I rip everything out and follow the schematics starting from scratch. I have already picked up a universal painless kit and would hate to screw this up because painless isn't exactly cheap. If anybody out there can help I could make a schematic of the pre-existing wires and e-mail it to you. I thought this would be easy since next semester I will have my degree in electrical tech but wiring a vehicle has become a whole new beast. Thanks for any help.

 

The Factory Diagrams are much more comprehensive.

Also of Note, most Factory main Wiring Harnesses of this era of truck are wired for every option these trucks came with (the only exception is Ammeter and Oil Gauges, if it came with idiot lights, it is not wired for gauges) . They just need an extra harness extention plugged into the main harness and the optional device to complete the circut.

So with that information, The Diagrams show wires for every option avaliable. Which some wires could be missing on the actual truck, harness extentions not pluged in or missing from the main harness, because it didn't have the option when new.

 

Thanks for the info. I plan on diving in tomarrow as soon as I get home. I was also wondering if you could clear something up for me. The schematics show three wires going to the distributor from the ignition module but the distributor only has one wire and was changed to points. Later I plan on updating the distributor but for now its going to have to work. Do I link all three together or just run one? I'll update you on how everything goes tomarrow even though it probaly wont be completed until this weekend. Thanks again, Jamie.

 

1975 should have a breakerless ignition..


The three wires is for a Breakerless ignition system. Which will require a module, and a different distributor with a pick up in it. That is what those three wires on the diagram refer to.

points distributor only has one wire.

 

Should or could I wire the distributor into the negative of the coil until I can get a different one? If I can should I throw in a ballast resistor?

 

I have a '75 F150 too and got the Ford Shop Manuals in the mail (including
the wiring diagrams) before Ford put the pickup together even. LOL :)

Just saw a post where they were $10 new and was thinking about getting
a new set since mine are about to fall apart. They will be well worth the
$10 to you, guaranteed. Buy 'em, use 'em, and I'll buy 'em from you if you
aren't satisfied. How does that sound to ya? ;)

Anyway If I were doing it, I wouldn't take anything out that was original
to the pickup. Figure out how the two systems work separately (what IS
a painless kit anyway? ...sounds like hype and jive to me) then figure out
where the two will match up and only do what's needed.

"it takes me longer when I get in a hurry" -Alvin

I said that to the signal supervisor just before he "rewired" a crossing case
so we wouldn't have to wait on a few trains. The gates didn't go down until
after all the engines in the "consist" went over the crossing and the gate
came down on the cab of a propane truck. The guys on the signal gang were
wanting to lynch "the smart guy" right then and there. I just said...
"it takes me longer when I get in a hurry" again while we watched the guy
in the propane truck staring at us and waiting on the gate to clear his truck.

Bet he wishes the same thing I did, he'd've just drove off breaking that gate
to pieces as soon as the train cleared the crossing.

The point of my rattlin' on is, take your time, understand what's going on,
and carefully do it -right- the first time. Wiring and re-wiring takes longer
than you'll figure it should ahead of time. BTDT
...seems like every time too. LOL :)

BTW, what he did looked "fine on paper" just like I told him but also told
him (since he wasn't a signal wireman) that "you can't count on the plans
being the same as what's in the case" and "every set of plans has mistakes
in it and it's up to the wireman to make it safe and work right, you don't
know what you've got until you chase every wire :/" He didn't understand
hands-on wiring and prob'ly figured I was just screwing the pooch when it
took me as long as it did to re-wire a case let alone a relay house.

It ain't plumbing. ;)
If it were plumbing your pickup would look like a oil refinery, there's so many
wires going everywhere. ;) And over the years Ford engineers figure out
sneaky ways to reduce the wires needed too.

The original wires in your pickup can be counted on to be "right" according to
the plans (not like some of the signals that had been in service since 1925)
...but, you'll need to -look- and see to be sure where they've been monkeyed
with (see the thread about "previous owners" and the wiring problems they
left) and go from there... and do it right or don't do it at all.

I've seen two different vehicles burned up right after a CD player install.

"do it right or don't do it at all ;)"

You can do it, as long as you don't give yourself a friggin time limit. :)

Alvin in AZ

 

On the Points system, this is how the distributor is wired anyway.


Negative coil wire to the distributor wire. It does not have ballast resistor on the negative side.

I would also follow Alvin's advise.

We already know the trucks been messed with, because it has a points system.

Breakerless ignition systems started in mid to late year 1974 models.

1975 never came with points from the factory.

 

Sounds like a good idea to me and in the process of drawing up your
schematic you might find out you really don't need help after all. ;)

Email it to me and I can put it on my website.

"keeping it out in the open" is what's so cool about the internet.
I don't have to be careful to know or tell you -everything- I've/we've
got "back up"! :)

Alvin in AZ

 

Hey sorry I havent got back to you guys. I usually get feedback at my email account. I just happened to come here to check up on some info and found more replies. Thanks a lot and if you still want that schematic I can get it on pspice and send it. Auhh, where do I send it? I actually put the wiring on hold because Im making a custum gauge cluster for the dash and didnt want to sell my self short (taking your advice and taking my time, plus its cold as hell outside and its hard to work with your hands if you cant feel your fingers-LOL).