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Joined
Jul 14, 2023
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Location
Germany
My Car
Mustang Mach 1 Fastback 1973
Hi guys, today I need your help when it comes to assigning the cables to the starter relay.

There is the Block Assy Junction next to it in the 73 model. In many restored models, this was simply removed, and the cables were connected directly to the relay, but I would like to make it true to the factory.

Which cables exactly were connected to the Assy at that time, and which cables were installed on the relay?

Original pictures or videos of your projects can also help!

Thank you very much
Ben
 

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I know @Hemikiller knows this stuff by heart, but I think we need to know what accessories the car came with. Some had additional items, based on the options. Post that info and I believe it will help narrow the response. If I’m wrong, @Hemikiller will let us know 😁.
 
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I know @Hemikiller knows this stuff my heart, but I think we need to know what accessories the car came with. Some had additional items, based on the options. Post that info and I believe it will help narrow the response. If I’m wrong, @Hemikiller will let us know 😁.
Yes, definitely @Steve McMahan ! :) Here the list of all the features my mustang had at Day Zero:
 

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Ben, I think you're only missing an option or two to equal David's (Carolina Mountain Mustangs) original owner '73 Mach 1 in option count.

The way that the solenoid and terminal block are wired in your picture looks correct. The 73 models (only) have a separate feed for the rear defrost, which is the Yellow on the terminal block. The circuit breaker below it is for the accessory power feed wire, and the other two are Black w/Orange stripe - one from the alternator, one from the main harness.
 
Ben, I think you're only missing an option or two to equal David's (Carolina Mountain Mustangs) original owner '73 Mach 1 in option count.

The way that the solenoid and terminal block are wired in your picture looks correct. The 73 models (only) have a separate feed for the rear defrost, which is the Yellow on the terminal block. The circuit breaker below it is for the accessory power feed wire, and the other two are Black w/Orange stripe - one from the alternator, one from the main harness.
Thank you very much for the great support! I was also very excited when I found out what great equipment the car had when it was delivered.

Unfortunately, due to my limited knowledge of English, I did not express myself correctly.

The picture was just an example. Not all cables are currently connected to my car for the reason that I am currently trying to find out with you which cables should be connected to the starter relay and which to the block. I need your help with this.

Here are some pictures from my engine compartment showing how I have currently wired up the cables and what is not yet connected and what type of cables are to fix. Im sure guys you can help me to bring them in the right order to get it done successfully. And maybe the connected ones are not at the right place currently? So dont hesitate to let me know if its wrong.

Ben
 

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Pics 1&2 are the connector for the brake warning switch on the proportioning valve

Pic 3 is the auxiliary power feed wire, it connects to the a circuit breaker on the terminal block, the connector has broken off
Pic 4 is the rear defroster power feed, also terminal block, but the ring terminal and flag have broken off
Pic 5 shows the female bullet connector for the hood light - if optioned

Skipping to Pic 10
1- AC compressor
2 - need to know wire & tracer color - possibly emissions solenoid
3 - Looks like Red w/Yellow Hash marks ? If so that's the throttle position solenoid (anti dieseling)
4 - need to know wire & tracer color - possibly emissions solenoid

*** this is the engine gauge harness and looks in rough shape, I'd suggest a new reproduction.


Pic 11
Black w/Orange stripe belongs on the terminal block, there should be another Black w/Orange stripe

Why do you have two wires on the starter side of the starter solenoid? If one of those is the negative battery cable, that attaches to the block.
 
If you haven't already obtained the wiring diagrams for your car they are available on the forum Wiki:
https://wiki.7173mustangs.com/

Post #3 in this thread has a guide on reading wiring diagrams
https://7173mustangs.com/threads/how-to-read-wiring-diagrams.40106/#post-413573

You can also download colorized versions of the wiring diagrams (for a price), which are nice for helping to sort out and trace the wires in the diagrams:
https://fordmanuals.com/product/1973-colorized-mustang-wiring-diagrams/
 
Thanks to everyone!

The "black" cables have been sprayed over by the previous owner ... I'll clean them as best I can over the next few days.

Why do you have two cables on the starter side of the starter solenoid? Is one of them the negative cable from the battery connected to the block.

To answer your questions, that was precisely why I asked. I want to get everything right, but I'm not a specialist in reading wiring diagrams to be honest.

I'll get back to you when I've tried to clean the other cables.
 
Pics 1&2 are the connector for the brake warning switch on the proportioning valve

Pic 3 is the auxiliary power feed wire, it connects to the a circuit breaker on the terminal block, the connector has broken off
Pic 4 is the rear defroster power feed, also terminal block, but the ring terminal and flag have broken off
Pic 5 shows the female bullet connector for the hood light - if optioned

Skipping to Pic 10
1- AC compressor
2 - need to know wire & tracer color - possibly emissions solenoid
3 - Looks like Red w/Yellow Hash marks ? If so that's the throttle position solenoid (anti dieseling)
4 - need to know wire & tracer color - possibly emissions solenoid

*** this is the engine gauge harness and looks in rough shape, I'd suggest a new reproduction.


Pic 11
Black w/Orange stripe belongs on the terminal block, there should be another Black w/Orange stripe

Why do you have two wires on the starter side of the starter solenoid? If one of those is the negative battery cable, that attaches to the block.
@Hemikiller some questions for better understanding.
Black w/Orange stripe belongs on the terminal block, there should be another Black w/Orange stripe
The second one, do you mean, is the one from the alternator wire harness, correct?
*** this is the engine gauge harness and looks in rough shape, I'd suggest a new reproduction.
Still in my inventory, thanks
Why do you have two wires on the starter side of the starter solenoid? If one of those is the negative battery cable, that attaches to the block.
at the end of the sentence, do you mean also the terminal block or the engine block or engine compartment? Just to understand it correctly :)
 
@Hemikiller some questions for better understanding.

The second one, do you mean, is the one from the alternator wire harness, correct?

Still in my inventory, thanks

at the end of the sentence, do you mean also the terminal block or the engine block or engine compartment? Just to understand it correctly :)

One Black w/orange from the engine compartment harness and one from the alternator harness

Sorry, engine block as below #10

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One Black w/orange from the engine compartment harness and one from the alternator harness

Sorry, engine block as below #10

View attachment 89465
That's great. Thank you very much. My new wiring harness is ready for installation. My old one has one more wire. it's brown with yellow dots. So do you know what wire it is? It's part of the wire channel to the oil sensor near the firewall on the old harness, but just got cut off.
 

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hey guys, another update on my mustang!

the new wiring harness for the alternator for the 70 amp and the gauges has finally arrived after 3 weeks. everything looks good so far. however, i still have one question.

the yellow 37 wire for from the main harness including the 14g fuse link is actually still connected to the red-orange wire for amp meter as far as i can see. code no. 655.

where is it connected and is there also a fuse in between?

the yellow 37 cable is much thicker than the red-orange, won't everything 'fly away' if it is simply connected to the yellow 37 cable without anything?

on my diagram there is only a black dot with the code S-204 but no further details.

thank you in advance for your help!
ben
 

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hey guys, another update on my mustang!

the new wiring harness for the alternator for the 70 amp and the gauges has finally arrived after 3 weeks. everything looks good so far. however, i still have one question.

the yellow 37 wire for from the main harness including the 14g fuse link is actually still connected to the red-orange wire for amp meter as far as i can see. code no. 655.

where is it connected and is there also a fuse in between?

the yellow 37 cable is much thicker than the red-orange, won't everything 'fly away' if it is simply connected to the yellow 37 cable without anything?

on my diagram there is only a black dot with the code S-204 but no further details.

thank you in advance for your help!
ben
Take a look at these schematics (one with tachometer, one without tachometer). Hopefully this will help you firgure out what goes where.

Gil
 

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