Wiring harnesses

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Thomas Dennis

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Year one as the wiring harnesses for A bodies up to 74 Has anyone used these kits for 75 and 76 cars? I would like to run a little bit larger ALT and a AM FM radio. A simple radio will do. I know that 74 cars had seat belt interlock. Can those plugs be taped off? This is for my 75 Duster Thanks
 
1976 wiring is very different than '74
Can't tell you how different '75 is from '74.

Radio shouldn't be a problem. Look in your cars fusebox and see if there is a fuse or at least a fuse holder for the radio. That would be the simplest place to power it from. For the light at night it will also need a power wire spliced into the instrument lighting.

For a 60 amp alternator, I think the easiest is add a parallel feed from the alternator through a grommet. A little more work is to copy the factory option for 60 amp alt on '73 cars with rear defroster grid. Not sure what was done in '75.
 
I went through this for a friends car many years ago. There's a few changes to wiring every year. If you get a matching harness on both sides of the firewall bulkhead connector, you'll be fine. Or, go through and make sure everything on both sides of the cars bulkhead plug are correct. A copy of the FSM diagram for 75 and 74 is what you need. That and a release tool, thin pocket screwdriver, or suitable tool to release wires at the plugs and re-arrange as needed.

https://www.amazon.com/OTC-4461-6-P...ocphy=9051569&hvtargid=pla-499807761277&psc=1
 
I'm going to replace the entire wiring in the car front to back I like the factory replacement setup since the wire color codes match the factory wire colors and service manual
 
Wire color should be the last thing you're looking at. Mopars have notorious problems with the firewall connector. You should choose a harness that eliminates it. That is a huge upgrade and could stop your car from burning to the ground on the side of the road.
 
This reminds me of myself a few years back.
Not a mopar but I also have a 64 Fairlane, and I put in a new fancy radio with the plug ins for my phone, etc. I was patting myself on the back as I was cruising my neighborhood when all of a sudden things started to get dim and everything just slowly quit working... hahahaha
I hiked home and came back with a jumper pack after I unplugged the radio!
I just threw in a one wire 100 amp alt and its been perfect ever since. I didn't have to change any of my original wiring either.
Good luck!
 
I've been using the M&H harnesses that Year one sells for many years on my 3 1970 Darts and have always found them to be right on target. I've watched folks spend enormous amounts of money or time (read hundreds of hours) using one of the universal kits for wiring. The factory alternators in 1970 ran from 34 amps to 60 amps for fleet vehicles (cop cars and taxi cabs and such) and these fle et vehicles came from the factory with the main power wires through the firewall with a grommet and bypassing the bulkhead connector. You should do the same. Unless you have something aftermarket with huge power drains, I can't imagine why you would want to use an alternator over 60 amps. I found out the hard way that many alternators these days put out 100 amps or more and fried a whole set of underhood and underdash wires for my trouble with this "upgrade".
 
I am a fan of the M&H wiring from Year One. I ran a MAS wire to help the larger alternator. I am running the smallest Power Master now for 4 years.
 
The ammeter is the same for a late 1972 to 1975 Valiant. [per Motors manual]. The 1976 ammeter is a low current unit for the 1976 shunt wiring system ONLY. Your car can handle a 40 amp alternator safely. Anything over that and it may cook the firewall plug connector when the battery is low and charging a lot. There are ways to correct that safely.

Not sure why you'd change out all the wiring in the car. Usually , the underhood wiring gets poor due to heat hardening and oil. The interior wiring usually looks ok and can be repaired unless some wannabe electrician or mice gets there first.
 
All I can add is to remember that the alternator 'rating' is approximately maximum possible output.
The actual output in operation is only what is demanded.
On A-bodies, the optional 60 amp alt wiring seems to have first been implemented 1973 MY with the defroster option.

Another thing different by 1976 is at least two power feeds through the bulkhead instead of one. That may have been done before '76 too. IIRC there is a similar division of the power feeds in the steering column connection earlier in the 70s.
 
The interior wiring is hacked up and spliced They used household twist connectors. They spliced into the wiring and used a toggle switch for the dash lights. Engine harness isn't any better I feel safer just replacing it all
 
several years ago I was on my way home from a Mopar show around Seattle and there on the side of the road was a beautiful silver 67 Charger with smoke billowing out of the hood and interior. I stopped and gave away my fire extinguisher (NEVER LEAVE HOME WITHOUT ONE IN YOUR MOPAR). He got the fire out but it must have caused many hundreds of hours and dollars in repairs. NEVER SKIMP OR FUDGE ON WIRING/ELECTRICAL!!!
 
Thomas Dennis said:
The interior wiring is hacked up and spliced They used household twist connectors. They spliced into the wiring and used a toggle switch for the dash lights. Engine harness isn't any better I feel safer just replacing it all
Click to expand...
Easiest may be putting a wanted ad up for '75 engine & body wiring harness in good condition.
Otherwise spend as much time as needed to figure out what different between the years and options.
I'd look at '73 as well as '74 since niether 73 or 75 have the interlock.
For that, my suggestion is to start with a few critical items.
1. Is the bulkhead connector in the same location and fit in the same opening?
2. Is the starter relay, ECU and dash switches in the same location?
Then compare feeds and out of the steering column connector.
 
American Autowire is NOT M&H. American Autowire makes kits that have to be assembled, M&H sells direct replacement original harnesses.
Year One numbers are:
Engine forward harness: 1973 V-8-HU2, 1974 built before 10/12/73 - HU10, built after 10/12/73 - HU11
Dash Harness: 1973 - HU326A, 1974 - HU327A
Rear Harness: 1973 - RL73, 1974 - RL78
There are some model specific sub-harnesses for stuff like AC that are also available

These are very specific, very accurate reproductions.
 
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