Opinion on universal wiring harness

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Valiantknight

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So im planning on rewiring my dash and id like to update the harness and fuse box in its entirety. This seems to be a fairly pricy venture when looking at the complete reproduction harnesses offered by year one and EZ wiring so ive been surfing the net and came accross this 1970 - 1971 Plymouth / Dodge 8 Circuit Wire Harness fits painless update new | eBay Wanted to know if anyone has tried installing a somewhat universal harness and the challenges associated with it. Also if its worth the trouble to save afew hundred. Budget is about $250 right now
 
If you have reasonable electrical skills, it would be time consuming but fairly easily done. If you don’t like electrical work it could be a nightmare.
 
I rewired my car with only the knowledge of how to solder and FABO. With todays harnesses if ypu can read the fine print on the wire and see colors just fine its pretty easy. Sometime with universal kits the wires may not be long enough depending where you put the fuse block.My suggestion is to only unwrap on circuit at a time and complete it before you jump to another. I rewired my dart in about two days with somewhere around 14-16 hours total and not a single electrical gremlin since then.
 
Thanks for all the links! Ill be doing some studying tonight but i really appreciate all the input. Ive done some electrical in the past and im no expert but ive got soldering experience and a good multimeter so hopefully thats enough lol.
 
Thanks for all the links! Ill be doing some studying tonight but i really appreciate all the input. Ive done some electrical in the past and im no expert but ive got soldering experience and a good multimeter so hopefully thats enough lol.
It's really not. Most terminals are F type open barrel crimps and very little soldering, if any is needed. A typical multimeter's resistance measurements will only show really bad connections, but miss poor ones that will show up under load. If you can setup appropriate loads, you could use it to test for voltage drops.
 
I bought 1200 feet of wire in multiple colors and rewired my car, myself. If you get a good schematic, and blow it up, with a finger and concentration, you can do it yourself.
Did you buy the car for ride around in only, or did you buy it for a project to enjoy working on?
If you wish, I can send you the schematics for your car. You can go to OfficeMax or any other print shop and have them blow it up (mine is 2x3 feet).
 
I bought 1200 feet of wire in multiple colors and rewired my car, myself. If you get a good schematic, and blow it up, with a finger and concentration, you can do it yourself.
Did you buy the car for ride around in only, or did you buy it for a project to enjoy working on?
If you wish, I can send you the schematics for your car. You can go to OfficeMax or any other print shop and have them blow it up (mine is 2x3 feet).
I bought it to learn it. Was my daily for about 6 months then i had to start doing repairs, had afew electrical gremlins went under the dash and found it chopped and spliced to bits. Im an automotive technician by trade and ive got quality tools so im tackling the wiring head on and hoping to learn something.
 
In that case I'd say read up on the factory system and then fix what needs fixing.
I say this because the kits are not always following the program. Fine if you want or need to change the strategy, but otherwise its just making things complicated.

Splice in and/or replace terminals and wiring where needed.
The good open barel crimpers are pricey, such as the Packard ones and copies.
Perhaps the cheapest ones that might be decent are the IWISS 2412M.
I haven't tried them yet, but will be trying out their 2820 for some smaller terminals that kicked my butt the last couple days.

Sources for Chrysler type wire terminals
Not all of the terminals are easy to find or figure out. So that can be a challenging puzzle at times.

I say read up because i don't know what your background is. If you've worked on generator equiped jeeps will be a world of difference than say SAABs etc. etc.
At the risk of providing background that you already know.
The car has two power sources, alternator and battery. In these cars, the factory wired them together at the main splice. This main splice is where all of the other circuits are tied in except the starter motor. Whether the alternator is providing power or the battery is providing power, the power goes to the main splice and then wherever needed.

upload_2020-4-4_17-42-12-png.png


The gage Chrysler labeled 'alternator' is an ammeter. Why is labeled alternator I don't know. But if you notice the car is running on battery all the time, then the alternator isn't working. So in a way it is an alternator gage. LOL

On a 70 and 71, the main circuit and ignition is like this
upload_2020-7-6_18-51-23.png


In your car, we don't know why the electrics were modified/hacked/altered That's probably the first thing to figure out.
Was there a modification for some new fangled accessory (electronic ignition, stereo, whatever) or
was it because there was a problem?
Or one resulted in the other leading to revisit...

The connectors at the firewall and at the steering column are often sources of problems.

Factory service manuals have pretty complete diagrams and sometimes additional illustrations showing cable routing or circuit diagrams.
Sometimes they left it to the techs to draw their own...

Lots of good info here ranging from how the turn signals work to how to read the diagrams.
Master Technician Service Conference - Chrysler's Training for Mechanics

mymopar.com has some of the same but in pdf, along with some digitized factory service manuals.
 
Keep in mind that the cars are wired so they can be assembled on a production line. If you are doing your own “custom” wiring, you don’t need all the connectors. Some folks remove the connectors on the bulkhead, drill them out, and just run the wires through them directly to where they go. Same with some of other connectors.
 
In that case I'd say read up on the factory system and then fix what needs fixing.
I say this because the kits are not always following the program. Fine if you want or need to change the strategy, but otherwise its just making things complicated.

Splice in and/or replace terminals and wiring where needed.
The good open barel crimpers are pricey, such as the Packard ones and copies.
Perhaps the cheapest ones that might be decent are the IWISS 2412M.
I haven't tried them yet, but will be trying out their 2820 for some smaller terminals that kicked my butt the last couple days.

Sources for Chrysler type wire terminals
Not all of the terminals are easy to find or figure out. So that can be a challenging puzzle at times.

I say read up because i don't know what your background is. If you've worked on generator equiped jeeps will be a world of difference than say SAABs etc. etc.
At the risk of providing background that you already know.
The car has two power sources, alternator and battery. In these cars, the factory wired them together at the main splice. This main splice is where all of the other circuits are tied in except the starter motor. Whether the alternator is providing power or the battery is providing power, the power goes to the main splice and then wherever needed.

View attachment 1715557266

The gage Chrysler labeled 'alternator' is an ammeter. Why is labeled alternator I don't know. But if you notice the car is running on battery all the time, then the alternator isn't working. So in a way it is an alternator gage. LOL

On a 70 and 71, the main circuit and ignition is like this
View attachment 1715557264

In your car, we don't know why the electrics were modified/hacked/altered That's probably the first thing to figure out.
Was there a modification for some new fangled accessory (electronic ignition, stereo, whatever) or
was it because there was a problem?
Or one resulted in the other leading to revisit...

The connectors at the firewall and at the steering column are often sources of problems.

Factory service manuals have pretty complete diagrams and sometimes additional illustrations showing cable routing or circuit diagrams.
Sometimes they left it to the techs to draw their own...

Lots of good info here ranging from how the turn signals work to how to read the diagrams.
Master Technician Service Conference - Chrysler's Training for Mechanics

mymopar.com has some of the same but in pdf, along with some digitized factory service manuals.
My backround is in GM mostly so this is my first mopar. Concering the ignition and engine wiring the PO had setup a custom pertronix hei system, having seen it in other applications i had found it pretty neat at the time but as soon as my ignition started acting up and dying randomly at idle i gutted it and installed an msd setup (didnt feel like trying to learn how the conversion was done), so im all ready pretty familiar with the ignition system wiring never had a starting/idling issue after that. Where im foggy is the wiring for the headlights i find that they flicker and randomly loose light, Other issue i have is that the underdash wiring is just a straight hackjob and a mess. Modern radio was installed that im replacing and when i had got the car there was no gauge bezel just abunch of individual little gauge pods spliced and wired in. Im doing the full harness replacement becuase ive got some nice gauges coming in the mail, a updated reproduction bluetooth radio, and i plan of re installing the AC/ heating system that the previous owner pulled. I really appreciate all the help. I bought a 1970 service manual today and will keep touching back to that for refrence.
 
Keep in mind that the cars are wired so they can be assembled on a production line. If you are doing your own “custom” wiring, you don’t need all the connectors. Some folks remove the connectors on the bulkhead, drill them out, and just run the wires through them directly to where they go. Same with some of other connectors.
Was actually curious about the bulk head. Ive seen on here that other people have deleted it and routed the wires somewhere else is there a common place way of doing this or is it better to leave the bulkhead connectors in for ease of servicing the system. Id like to clean up the engine bay too but one problem at a time lol.
 
Firewall connectors are handy during assembly and diagnostics too. All of the cavities can be backprobed from eithe side, except the two power feeds on most years. Most years. Lemme say that again 'cause they are not all the same. Some years are very different than others.

On a standard '70 wiring setup the power feeds use the bulhead connector. These can see high current flow, especially with a higher output alternator feeding a low battery and other high demand situations. Chrysler had a couple strategies to provide a more robust wiring for cars equiped with 60 or 65 amp alternators alone or with rear window defrost grids. Those don't always show up in the shop manuals but you can do a search here for the drawings and even some photos.

Running the A/C at idle is one of those situations where an alternator with higher capacity at low rpm is helpful. I *think* some models/years had a A/C activated idle speed solenoid...

Gages. Factory used a reduced voltage (IVR) for these. Aftermarket usually runs at the system voltage.

Headlights flickering. Depending on the nature of the flickering at idle it could be...
voltage dropping because the alternator can't produce enough power at idle to handle everything.
alternator ripple
loose circuit connection (could even be internal to ignition switch) causing the the regulator to 'see' varying voltage.
circuit breaker weak or seeing too much current (possible wire chafing causing short).

That said, the a-body headlight circuit used 18 ga and 16 ga wires and has lots of connectors etc. It was OK with the original 6012 headlamps. But its not so OK even with the slightly higher wattage 6014 lamps that became available just a few years later. Changing the headlight circuit to power directly from the alternator using relays is a pretty good solution. This helps the headlights and also reduces load carried by the main power feeds. Then you can run any decent headlight you like without worries.
 
The headlight switch is a multifunction switch.
B1 only feeds the headlights
It has a 15 amp breaker.
B2 feeds the parking and marker lights.
upload_2020-7-7_7-44-25.png

B2 also feeds the instrument lights. The wiring for the instrument lights goes back to the fuse box.
Finally there is a connection for the dome/interior lights. This is a ground connection just like the door switches.
 
A member on here, crackedback, sells relay kits for the headlights that will improve brightness.
 
Firewall connectors are handy during assembly and diagnostics too. All of the cavities can be backprobed from eithe side, except the two power feeds on most years. Most years. Lemme say that again 'cause they are not all the same. Some years are very different than others.

On a standard '70 wiring setup the power feeds use the bulhead connector. These can see high current flow, especially with a higher output alternator feeding a low battery and other high demand situations. Chrysler had a couple strategies to provide a more robust wiring for cars equiped with 60 or 65 amp alternators alone or with rear window defrost grids. Those don't always show up in the shop manuals but you can do a search here for the drawings and even some photos.

Running the A/C at idle is one of those situations where an alternator with higher capacity at low rpm is helpful. I *think* some models/years had a A/C activated idle speed solenoid...

Gages. Factory used a reduced voltage (IVR) for these. Aftermarket usually runs at the system voltage.

Headlights flickering. Depending on the nature of the flickering at idle it could be...
voltage dropping because the alternator can't produce enough power at idle to handle everything.
alternator ripple
loose circuit connection (could even be internal to ignition switch) causing the the regulator to 'see' varying voltage.
circuit breaker weak or seeing too much current (possible wire chafing causing short).

That said, the a-body headlight circuit used 18 ga and 16 ga wires and has lots of connectors etc. It was OK with the original 6012 headlamps. But its not so OK even with the slightly higher wattage 6014 lamps that became available just a few years later. Changing the headlight circuit to power directly from the alternator using relays is a pretty good solution. This helps the headlights and also reduces load carried by the main power feeds. Then you can run any decent headlight you like without worries.
Well its been two years and a whole lot of life has happened I can finally get back to this project LOL.
do you happen to have a diagram for that headlight relay setup?
 
Yes but for a '67, so cavities and colors will be different on your car.
In general, the concept is as shown.
upload_2022-4-13_16-39-3.png


Illustrated is the headlight switch on, powering the low beam relay (black wire).

Some people prefer to plug into one of the original headlight connectors. Thats how crackedback makes his harness.
I think Daniel Stern has a scematic for that on his website, although its not too difficult to figure out from above.
 
Yes but for a '67, so cavities and colors will be different on your car.
In general, the concept is as shown.
View attachment 1715907018

Illustrated is the headlight switch on, powering the low beam relay (black wire).

Some people prefer to plug into one of the original headlight connectors. Thats how crackedback makes his harness.
I think Daniel Stern has a scematic for that on his website, although its not too difficult to figure out from above.
Seems straight forward enough I'll be tackling headlights once I go pick up some relays from the electronics store. Unrelated question I was looking over what I did for the msd with the intention to clean up some wiring, blue and brown wire from ign1 and 2 are hooked up to the small red but for some reason the blue wire from the voltage regulator and the alternator were also spliced into the connection is that the correct setup? There's no longer a balast in the car. It's a 70 valiant
 
As it sits currently this is how it looks. I know the rest of the msd6al unit is correctly installed but I was unsure if the switched + 12v should still be wired in with the alt and regualtor
upload_2020-7-6_18-51-23.png
 
I have one from Speedway Motors for my rat truck. It's a 21 circuit, which is WAY overkill, but I got it on one of their garage sales for 89 bucks with free shipping. It's fantastic quality and each wire is individually marked. Even came with GM style headlight switch, dimmer switch and a cool universal old school turn signal switch. As long as you have the ability to splice, terminate ends and so on, don't be afraid of it.
 
I have one from Speedway Motors for my rat truck. It's a 21 circuit, which is WAY overkill, but I got it on one of their garage sales for 89 bucks with free shipping. It's fantastic quality and each wire is individually marked. Even came with GM style headlight switch, dimmer switch and a cool universal old school turn signal switch. As long as you have the ability to splice, terminate ends and so on, don't be afraid of it.
I'll give that a look I'm coming back to this car with the intent of finishing it this year. Just looking back over where I left off on evrything since last year.
 
As it sits currently this is how it looks. I know the rest of the msd6al unit is correctly installed but I was unsure if the switched + 12v should still be wired in with the alt and regualtor View attachment 1715907174
Yes that is a correct way to connect it. The on/off wire will be on with key in Start as well as Run. it doesn't matter if the ballast resistor is there or not.
The voltage regulator reads the system voltage on Wire J2B. When the voltage is lower than set point it closes a connection between R3 and ground. A little more here.
 
I paid under $100 for a nice 20 circuit hot rod kit and made the investment from Amazon a good heat gun and bought a bunch of their solder filled butt connectors.. it was nice having every connection soldered and shrink wrapped quickly and nicely.... Also eliminating that ugly bulkhead under the hood and being able to tuck my wires...
Also found that tucking everything in a wire loom holder made for neet tidy work..
PXL_20211230_225313172.jpg
PXL_20220206_011854276.jpg

I even got some Amazon 30 amp relays with fuses and hung them from the battery tray for the headlight and fan relays...
One hell of a time consuming but I'm very meticulous...
 
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