Re-Wiring 1975 Plymouth Duster

[Wrivera]

This is my first post, I am stationed at an Air Force base in New Jersey, originally from CT, my father passed down his 1975 Plymouth Duster to me but when I received it, there was no power running to the rear lights, front lights, or dash. Upon investigation I found a mess of wiring (including ridiculous speaker wiring and random old wiring leads spliced into old wires) . I have decided to rewire the car myself, this is my first rewire job, so I'm nervous to say the least. any pointers or schematics (I have not been able to find a wiring schematic for the 75 Plymouth duster), or any insight that you all can give for a smooth rewiring job?

Attached images show the car.

 

[H22A4]

Welcome! That’s a clean Duster and great to see another ‘75 A body around!

There is a service manual book which includes wiring diagrams for the ‘75 cars. There’s another Mopar website that has the service manuals for most (all?) of the years so try googling it. They have been scanned into pdf format.

Here‘s a hard copy I picked up at a swap meet a couple of decades ago for my ‘75 Scamp.

 

[67Dart273]

75 and 76 has no easy answers, or maybe "cheap." You are going to have to search around and either find an origininal, or "repop" / reprinted, or "on CD" service manual for that year. The wiring over the years has changed some, and you need the correct manual.

MyMopar.com is the website the guy above was thinking of, but they do NOT have the correct manuals

They do have aftermarket, 2 page manuals you can download --in the wiring section-- but those are NOT detailed enough, they are, however, somewhat easier to follow for some problems in order to understand the system. In other words "I use both."

However, are you intending to buy used/ new harnesses, that is reproduction harnesses, or are you going to use a more "universal" approach, which many do?

If you are going to use a universal harness, that of course is even more intimidating, as they do not follow original wiring, and that is sometimes a good thing. The universal harnesses are better fused with more circuits.

 

[mopowers]

Ebay's got body service manuals for 75 Dusters. They aren't free, but it'll have every wiring diagram you need in it. Mymopar has them for 73's, so if it's close enough, you can get that one for free.

 

[Wrivera]

75 and 76 has no easy answers, or maybe "cheap." You are going to have to search around and either find an origininal, or "repop" / reprinted, or "on CD" service manual for that year. The wiring over the years has changed some, and you need the correct manual.

MyMopar.com is the website the guy above was thinking of, but they do NOT have the correct manuals

They do have aftermarket, 2 page manuals you can download --in the wiring section-- but those are NOT detailed enough, they are, however, somewhat easier to follow for some problems in order to understand the system. In other words "I use both."

However, are you intending to buy used/ new harnesses, that is reproduction harnesses, or are you going to use a more "universal" approach, which many do?

If you are going to use a universal harness, that of course is even more intimidating, as they do not follow original wiring, and that is sometimes a good thing. The universal harnesses are better fused with more circuits.

Thank you for the reply I am going to switch out the old cartridge fuses for a 21 circuit plug fuse with a labeled universal wiring harness.

 

[Wrivera]

Welcome! That’s a clean Duster and great to see another ‘75 A body around!

There is a service manual book which includes wiring diagrams for the ‘75 cars. There’s another Mopar website that has the service manuals for most (all?) of the years so try googling it. They have been scanned into pdf format.

Here‘s a hard copy I picked up at a swap meet a couple of decades ago for my ‘75 Scamp.

View attachment 1716038146

View attachment 1716038147

Thank you she is fun to drive when she is running I searched a few other sights but it seems pretty difficult to find a downloadable one for the 75 Duster. Im thinking i will have to purchase one online.

 

[H22A4]

What’s under the hood? With that scoop I doubt it’s a slant 6 or a 2bbl 318?

Buying a downloadable manual will be worth it in the long run. You’ll refer to it a lot to fix the existing wiring problems and it will be the proper road map instead of using generic ones. The later year A bodies have extra safety/gizmos that are not in the earlier more available manuals. At least they got rid of the seat belt safety interlock in ‘75 (it was a 1 year only item for ‘74) as it caused a lot of problems.

 

[67Dart273]

Ebay's got body service manuals for 75 Dusters. They aren't free, but it'll have every wiring diagram you need in it. Mymopar has them for 73's, so if it's close enough, you can get that one for free.

There are two volumes, body and chassis. Traditionally, the chassis manual has the complete diagrams, not the body manual. You really need both to have a "complete" manual

 

[NoCar340]

I'd suggest sticking with factory harnesses, just for the fact that everything corresponds to the service manual. That's a huge advantage when a gremlin appears. I have original FSMs for all my cars, but one to consider is the "manual on CD" by Bishko (eBay link--bonus, it's 40% off at the moment). I have one of theirs for my '82 Imperial (that wiring is insane). If I know I'm gonna get filthy, I just print the pages I need and take those out to the garage. If my prints get greasy or wrecked, I just print more.
Year One has the best 100%-factory-style harnesses. They bought the factory connector tooling decades ago. They're made my M&H Electrical Fabricators, who do top-notch work but cannot sell you one (exclusivity contract; Year One owns the tooling). Classic Industries literally buys theirs from Year One. I've used several and they're excellent.
Get on Year One's mailing list; within a week or two you'll get a 30% off discount code, which is absolutely necessary considering the prices--the dash harness for my Challenger was around $600 without it.

 

[jos51700]

Get a factory replacement harness. Pull the speedo unit and glovebox liner, and get to it. Get some die-electric grease and grease every connector. It isn't that bad and is actually a relaxing job.

Pulling the front seat is optional.

 

[Wrivera]

Get a factory replacement harness. Pull the speedo unit and glovebox liner, and get to it. Get some die-electric grease and grease every connector. It isn't that bad and is actually a relaxing job.

Pulling the front seat is optional.

I have pulled the front bench seat and rear seat, next im going to pull the glove box and instrument cluster. Im hoping that will give me enough access to see what im doing without having to pull the dash. Should i pull the old fuse block and snip associated wires first to have a "clean" start or go cable by cable replacing existing wiring from component and old fuse box with new wiring to component and new fuse box? Thoughts?

 

[triumphman]

Not expressing what direction you can go, that is up to you, but: I made these charts from a 1975 Dart Swinger manual.
What they show in the manual is a backsided twisted view of the Bulkhead connector.
As mentioned earlier you need to disconnect every connector and clean them.
Become familiar with which side you are looking, and good luck.
Also, there is the "Seat belt safety interlock system" that has 17 wires, I cut all of them out. You will need a factory manual to know what to cut out, if you do that.

 

[triumphman]

As for the fuse block, the "high speed" wire there is most likely burned. I drilled out the hole for high speed, ran the correct color and gauge and put an "in line" fuse in its place.

 

[mopowers]

There are two volumes, body and chassis. Traditionally, the chassis manual has the complete diagrams, not the body manual. You really need both to have a "complete" manual

Yep, there are two. The 1973 Body manual includes most of the circuits he'll need - not sure about the '75. I would definitely get both. No reason not to.

 

[CRUZE 418]

My 2 cents, if you have the money, get the whole thing from Year One, M&H. If the car ever goes down the road and has a wiring problem, they will thank you. The wiring harness in my '69 was so damn clobbered, I threw it away and put in the M&H harnesses, absolutely no regrets. It's your car.

 

[missing linc]

There are some differences between the 73 model year and 75, which could cause confusion at the least, or major short circuits at worst. I have found wiring diagrams for 75 Darts by searching on Google. They may not be all inclusive but an aftermarket harness will likely be more GM oriented. Just my .02.

 

[Demonx2]

So I've rewired both of my Demons. The avatar car used my own design - started it with not one inch of copper wire in the car. Used HayWire wiring for the fuse blocks and source for all components. Darren there is great to work with. But as noted, aftermarket harnesses are generally GM-oriented (like the turn signal connector). They can be made to work and Darren can advise. I ran all the circuits and wiring to my design.
My 71 Demon uses Evans Wiring repop harnesses (except for the front end lighting harness which is M&H). Excellent fit and accuracy of harness lengths etc but I don't think he makes harnesses for 75's. A call to him can confirm. But as others noted, M&H harnesses are also known to be very good. My M&H front end lighting harness works but the breakouts were not in exactly the right places compared to the original i pulled out but I was able to make it work.
So you have to decide which way you want to go - repop or custom. Either will work and I found them to be fun adventures. Just keep EXCELLENT records for whatever you do. Especially for any/all mods you do to the stock wiring. If you go the custom route, of course you will keep great records!!

Good luck - gave fun doing it. You'll feel good pulling 50 yr old crusty, crispy, filthy wiring out and putting new clean harnesses in!!

 

[Mattax]

there was no power running to the rear lights, front lights, or dash.

I have decided to rewire the car myself, this is my first rewire job, so I'm nervous to say the least. any pointers or schematics (I have not been able to find a wiring schematic for the 75 Plymouth duster), or any insight that you all can give for a smooth rewiring job?

Send me a PM. You're not that far away and I can give you a hand getting started.
There's a West Marine where a wide variety of gages and insulation color wire can be purchased by the foot.

I have pulled the front bench seat and rear seat, next im going to pull the glove box and instrument cluster. Im hoping that will give me enough access to see what im doing without having to pull the dash. Should i pull the old fuse block and snip associated wires first to have a "clean" start or go cable by cable replacing existing wiring from component and old fuse box with new wiring to component and new fuse box? Thoughts?

Do NOT cut.
Figure out what it needed.
One approach, that may be appropriate is to remove the harness and lay it out on a plywood.

1975 wiring has some unique circuit arrangements.
An original option that is critical to know is whether the car was originally equiped with a defrost grid for the rear window. Those cars came with a heavy duty alternator and battery wiring arrangement. One clue will be the rear window itself and/or the switch to turn it on. The other clue will be a grommet in the firewall with some large wires.

A pdf of the '75 valiant/dart wiring diagram from a service manual in this post.

Here's the scheme for the main power feeds.
A1 is Battery feed.
R6 is alternator feed.

With the key off, everything connected to the battery positive is still hot. Take your finger and trace the wire route from the battery positive. The ammeter is just another section of the line. Nothing magical happens there, its two studs and a big metal plate that electricity can flow through in either direction. The color change is so the hookup is correctly done. That way the needle will point the correct way when the battery is discharging or charging.

The feed to the headlight switch B1 terminal is direct from the welded junction. It's always hot when the battery is connected.
The feed to the headlight switch B2 terminal is through the the fuse box. It too is always hot, but is fused.
J1 is the power feed to the key switch. If the large wire (red with white stripe) to the column connector is hot, then there ought to be power to the headlights, brake lights and dome lights.



Some '75 model year cars still got the '74 seatbelt interlock.
Hopefully your does not have that, but if it does, then you'll have to deal with it.

 

[Mattax]

That way the needle will point the correct way when the battery is discharging or charging.

When the engine is running, the ammeter should at first show charging of the battery and then center.
If it shows discharging, then something is wrong with the alternator or alternator circuit.
The ammeter is calibrated to indicate 40 amps to 40 amps. Either extreme indicates a big problem. turn off the engine.

To make nice factory like connections, get some open barrel crimpers and selection of Packard type 56 and 58 type terminals.

 

[NoCar340]

AuVeCo sells both sides the Chrysler-style terminals in bulk (25pk, I think) pretty inexpensively, as well as some of the insulators (mostly just single-terminal stuff, though). Check with an auto-body supply store or parts store that sells paint.

The AuVeCo catalog is well worth the price of admission ($13.50 last I checked).

 

[72Duster440]

Thank you for the reply I am going to switch out the old cartridge fuses for a 21 circuit plug fuse with a labeled universal wiring harness.

That's what I did. I went with a Painless Wiring 10102 kit. It was pretty straightforward, although the ignition circuit was a little confusing. My car is bare bones though, lights, turn signals and a radio, nothing else to wire, so it might have been a little easier than most. The kit only came with GM style steering column connections, so I had to reuse the stock one.

Terminal Supply Co has every connector/pin/socket you might need as well to work with the old stuf that stays in the car.

 

[66fyssh]

@Wrivera that's a very generous offer from @Mattax. He knows wiring, for sure!! Shoot Mattax a PM and touch base at least.

Thank you for your Service!! I'm retired Air Force myself. Never stationed at McGuire / Fort Dix though.

 

[Wrivera]

UPDATE: The first picture is what it looks like under the hood. it has a 360 engine in it (obviously not stock).

As i am trying to identify components I am noticing how difficult it is trying to use a stock Schematic on a car that has sort of been Frankensteined over the years.

The second image is of the firewall, the connector circled is a connector i cannot seem to find a pin layout of I am hoping someone can help.

 

[NoCar340]

That's the bulkhead disconnect, the main pass-through from the engine bay to the interior and vise-versa. It's clearly laid out in the factory service manual wiring diagrams describing color codes and each cavitiy's corresponding position in the harness that plugs into it. It's also shown in post #12.

If you still haven't bought a service manual, you're spitting windward.

 

[Mattax]

An original option that is critical to know is whether the car was originally equiped with a defrost grid for the rear window. Those cars came with a heavy duty alternator and battery wiring arrangement. One clue will be the rear window itself and/or the switch to turn it on. The other clue will be a grommet in the firewall with some large wires.

it was optioned. Does it have the rear defrost grid? Does it still ahve the fender tag?

We see some modifications but a lot of factory still there as well.