1972 Monte Carlo wiring help needed! - Chevelle Tech
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post #1 of 6 (permalink) Old Jan 1st, 16, 8:01 PM Thread Starter
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Anthony
 
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1972 Monte Carlo wiring help needed!

Hi all. I have a 1972 Monte Carlo that I've LS swapped.

I'm trying to find the main power wire that basically powers the whole car. I'm horrible with wiring and I hate it so go easy on me lol.

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post #2 of 6 (permalink) Old Jan 1st, 16, 9:08 PM
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Re: 1972 Monte Carlo wiring help needed!

From what I've learned through the years is there is a main feed that passes through the bulkhead connector on the firewall face and it's pretty much in a standard location on the plug.

Looking at what you have, seperate the wire groups going to the bulkhead connector. I'll take it easy here but on the face of the firewall a group of wires go into a multi-pin connector and in the middle of the connector is an attachment bolt. This plug once unbolted off of the face of the firewall can be taken apart into two plugs with multiple wires going into each one (and some slots will have nothing in them).

Once you get the wires grouped to this plug you should have a group that would go to the motor wiring (distributor, oil and water senders, etc) and another group that goes to the front end wiring (headlights, front turn signals, front parking lights, etc). I have to think that on the half of the plug that goes to the front end lighting, there will be your main feed wire.

At some point GM changed wiring setups in that years ago off of the bulkhead connector the main feed wire was getting power from the horn relay/junction point while others had the main power from the bulkhead connected to a junction block on the firewall close to the bulkhead connector.

I can only zoom in so much with your photo's but I have a feeling there in the one group of wires on one half of the bulkhead connector will be about a 10-12 gauge red wire. This is probably your main feed into the car and it will also be there with the wires for the headlights and front signal lights.

Depending on the wiring is on the car is you want to make it safe. GM had fusible links in spots to where if there was a short past it the fusible link burned apart and who knows if yours are still in place and/or good.

I would get a factory wiring diagram and layout what you have using it as a reference.

A good tool to get familiar with is a volt meter. While you can buy or use just a voltmeter for things, I would get a decent volt/ohm meter and you will find yourself using it later for other things.

Jim

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post #3 of 6 (permalink) Old Jan 1st, 16, 9:34 PM
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Joe
 
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Re: 1972 Monte Carlo wiring help needed!

In the original 1972 set-up, power was "grabbed" from the main large battery (+) connection at the starter solenoid. GM took advantage of the fact that battery power was already there (via the large (+) battery cable), rather then grabbing power from the battery terminal and running power across the front of the car and then to the firewall like as found in earlier models.

A 14 ga. fusible link connected to the starter solenoid main (+) lug, then spliced into a red 10 ga. wire (the main power feed for the whole vehicle). This wire then ran straight up, across the firewall to the horn relay's threaded stud where it met up with the other connections (such as the 16 ga. fusible link wire, ultimately leading to the bulkhead connector) to feed all interior power.

Please check out Russ's site to see what things looked like (although his harness does have some modern mod's..

http://www.cars.russgreen.net/1972_S...ss_wiring.html

You may be better off replacing wiring rather then trying to "fix" as once things get tampered with that badly, a lot of the safety and safety featurs (like fuse links) are compromised.

-If you don't stand for something, you'll fall for anything.
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post #4 of 6 (permalink) Old Jan 1st, 16, 10:54 PM Thread Starter
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Anthony
 
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Re: 1972 Monte Carlo wiring help needed!

Quote:
Originally Posted by Jim Streib View Post
From what I've learned through the years is there is a main feed that passes through the bulkhead connector on the firewall face and it's pretty much in a standard location on the plug.

Looking at what you have, seperate the wire groups going to the bulkhead connector. I'll take it easy here but on the face of the firewall a group of wires go into a multi-pin connector and in the middle of the connector is an attachment bolt. This plug once unbolted off of the face of the firewall can be taken apart into two plugs with multiple wires going into each one (and some slots will have nothing in them).

Once you get the wires grouped to this plug you should have a group that would go to the motor wiring (distributor, oil and water senders, etc) and another group that goes to the front end wiring (headlights, front turn signals, front parking lights, etc). I have to think that on the half of the plug that goes to the front end lighting, there will be your main feed wire.

At some point GM changed wiring setups in that years ago off of the bulkhead connector the main feed wire was getting power from the horn relay/junction point while others had the main power from the bulkhead connected to a junction block on the firewall close to the bulkhead connector.

I can only zoom in so much with your photo's but I have a feeling there in the one group of wires on one half of the bulkhead connector will be about a 10-12 gauge red wire. This is probably your main feed into the car and it will also be there with the wires for the headlights and front signal lights.

Depending on the wiring is on the car is you want to make it safe. GM had fusible links in spots to where if there was a short past it the fusible link burned apart and who knows if yours are still in place and/or good.

I would get a factory wiring diagram and layout what you have using it as a reference.

A good tool to get familiar with is a volt meter. While you can buy or use just a voltmeter for things, I would get a decent volt/ohm meter and you will find yourself using it later for other things.

Jim
What's not pictured in my hand is 2 10g wires that were spliced in at some point. One part of the wire has a connector for the alternator and the other is just cut off. Unfortunately the wires just fell out so at some point they were connected to the main feed wire but no longer are
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post #5 of 6 (permalink) Old Jan 1st, 16, 10:57 PM Thread Starter
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Anthony
 
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Re: 1972 Monte Carlo wiring help needed!

Quote:
Originally Posted by Coppertop View Post
In the original 1972 set-up, power was "grabbed" from the main large battery (+) connection at the starter solenoid. GM took advantage of the fact that battery power was already there (via the large (+) battery cable), rather then grabbing power from the battery terminal and running power across the front of the car and then to the firewall like as found in earlier models.

A 14 ga. fusible link connected to the starter solenoid main (+) lug, then spliced into a red 10 ga. wire (the main power feed for the whole vehicle). This wire then ran straight up, across the firewall to the horn relay's threaded stud where it met up with the other connections (such as the 16 ga. fusible link wire, ultimately leading to the bulkhead connector) to feed all interior power.

Please check out Russ's site to see what things looked like (although his harness does have some modern mod's..

http://www.cars.russgreen.net/1972_S...ss_wiring.html

You may be better off replacing wiring rather then trying to "fix" as once things get tampered with that badly, a lot of the safety and safety featurs (like fuse links) are compromised.
I actually looked at that and it told me the color of the wire and where it runs but I was still unable to find it. I was hoping to use the ignition key to start the car but I think I may just hook up a push start from the store.

And I think I'm just going to replace the front end wiring now. Especially after looking at everything.
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post #6 of 6 (permalink) Old Jan 1st, 16, 11:08 PM Thread Starter
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Anthony
 
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Re: 1972 Monte Carlo wiring help needed!

Will this kit work? I don't have the money for the 600$ kit.
http://www.americanautowire.com/shop...-13-wiring-kit
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