Another noob dumb question re electrics

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Ballaratcastle

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May 29, 2018
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Location
New Zealand
My Car
1973 Mustang Convertible. Just imported from the USA as an unfinished project.
[url=https://ibb.co/gXU4Qy][img]https://preview.ibb.co/f0tW5y/Mustang.jpg[/img][/url]
So team as mentioned in previous posts I imported an unfinished project 73 vert. Am completely bumbling my way thru the rebuild. 

The wiring looms on my car had just been cut and left unlabelled but I was lucky enough to find a donor 73 grande that had been sitting in a paddock for 12yrs and grab the front and rear looms labelling what I could (no engine so still couldn't label all the unidentified wires)

 I have just got to the point of rerunning the donor loom but there is a small difference between the single wire that runs thru the firewall separate from the main loom compared to the one that was in my car. 

My car had a thick black wire terminating I think at the battery with a small relay but the one out of the donor car terminates at the battery with a spade type connector. At the other end through the firewall they each have a different plug. Firstly can someone tell me what this separate is wire for please and why two different plugs. I haven't found the mate to my old wire yet as I may reuse my one.

SORRY CANT SEEM TO UPLOAD IMAGES FOR SOME REASON WILL KEEP TRYING

 
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It sounds like you are referring to the accessory wire harness.  In Convertibles, this wire supplies power to the power roof switch. Also if you have the convenience group options such as automatic seat back release.

This harness connects to either the battery side of the starter solenoid or a terminal block near the solenoid and the other end has a yellow  3 pin female plug which is placed behind the LH kick panel.

This harness also has a wire pigtail with a black single pin female plug about one third down the wire from the solenoid end. This plug is for the under hood mercury light switch, which was part of the convenience group option.

Also, the harness supplied power to the power window solenoid mounted to the shock tower near the brake distribution block.





 
Last edited by a moderator:
It sounds like you are referring to the accessory wire harness.  In Convertibles, this wire supplies power to the power roof switch. Also if you have the convenience group options such as automatic seat back release.

This harness connects to either the battery side of the starter solenoid or a terminal block near the solenoid and the other end has a yellow  3 pin female plug which is placed behind the LH kick panel.

This harness also has a wire pigtail with a black single pin female plug about one third down the wire from the solenoid end. This plug is for the under hood mercury light switch, which was part of the convenience group option.

Also, the harness supplied power to the power window solenoid mounted to the shock tower near the brake distribution block.



Thank you so much. Yes my original lead has the yellow plug. Apologies I have tried to upload a photo but it will not save.. 

The one out of the Grande has a square T shape plug so maybe that was for the other functions you mentioned. I will reuse my original one I think. Mine does have a small relay attached at the termination point though and the yellow one from the Grande is definately connected to a battery terminal 

The male plugs for the yellow fitting must have fallen inside the kickpanel next to the foot brake. 

Cheers

 
Not sure what the square plug is in the first picture. In the last picture, you show the circuit breaker for the accessory harness which attaches to the starter solenoid or the terminal block.

 
I find the wire harness on the 71 - 73 very confusing myself. Each car is sort of unique. The harness was built originally to fit the specific car. Even though you got one off another mustang it might not be the right one.

If your car had gauges the harness will be different than if you just have warning lights. A convertible will be different than and coupe and Mach 1.

It took me months to locate a correct one for my 73 convertible. Air conditioned car is also different from non air. 

Here are some pictures that might help.









 
Thanks for the photos. I will check them closeqqly. Both theqq donor grqandqeq and my car only have a theqq idiot lights clusterr and no Aircon but my loom laid side by side is similar but my car didn't come with the regulator ??the bigger Box (in your photo)that sits under the starter solenoid or the other small black box that sits Infront of the washer bottle on the driver front apron so I have grabbed these from the grande. 

I have a work colleague who is an ex mechanic and very good with wiring who is coming to look at the car on Friday.

 
Midlife Harness Restoration is a great source of information. I suspect that if you sent him everything you had, wiring wise, the he could put together a complete and functional harness for a fair price. If you aren't familiar with automotive wiring, letting him do that would save a lot of headaches.

 
Rather than do another post I'm also looking for the best spot to mount the electronic coil for the dizzy. It can't go on the motor like the standard coil so open to suggestions but gather as close to the dizzy to minimise the length of coil lead needed



 
Midlife Harness Restoration is a great source of information.  I suspect that if you sent him everything you had, wiring wise, the he could put together a complete and functional harness for a fair price.  If you aren't familiar with automotive wiring, letting him do that would save a lot of headaches.
Cheers mate. 

I'll Google him but as I'm in New Zealand it makes it a bit tricky time and freight wise. I have most of my old loom and the donor one and everything looks the same except for that accessory wire having a different plug. The voltage regulator never arrived with the car either so lucky I grabbed the complete system from the other car

 
It sounds like you are referring to the accessory wire harness.  In Convertibles, this wire supplies power to the power roof switch. Also if you have the convenience group options such as automatic seat back release.

This harness connects to either the battery side of the starter solenoid or a terminal block near the solenoid and the other end has a yellow  3 pin female plug which is placed behind the LH kick panel.

This harness also has a wire pigtail with a black single pin female plug about one third down the wire from the solenoid end. This plug is for the under hood mercury light switch, which was part of the convenience group option.

Also, the harness supplied power to the power window solenoid mounted to the shock tower near the brake distribution block.



Thank you so much. Yes my original lead has the yellow plug. Apologies I have tried to upload a photo but it will not save.. 

The one out of the Grandé has a square T shape plug so maybe that was for the other functions you mentioned. I will reuse my original one I think. Mine does have a small relay attached at the termination point though and the yellow one from the Grandé is definately connected to a battery terminal 

The male plugs for the yellow fitting must have fallen inside the kickpanel next to the foot brake. 

Cheers
Mine had one of those, plugged into the rear window defroster.

I pulled it out and just ran new wiring using a circuit breaker, a relay, and a pair of blade-style fuse blocks for all of the new power goodies I added (rather than cut into the factory harness).

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It ain't as pretty as it could be, but I have lots of power and everything's waterproof. ;)

 
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