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Hey, am I right, that on a 73 Grande, the Yellow, fuse link wire, from the positive side of the battery, is the electrical “feed” for the rest of the vehicle? I’m at the layout stages of the 87 TBird swap and I have wiring diagrams, etc and I believe I am correct. Am I?

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Generally speaking, you are correct. However, newer cars can have more than one fusible link, not sure if you're wondering about your Grande or T-bird nor which one you have the wiring diagrams for. You can down load wiring diagrams for your '73 Mustang from the 7173 Wiki section of this forum.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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I am trying to ascertain if that one, looks like 8 gauge wire, is the primary source of 12 volt dc power for the original electrical system? Forget the modification. Also, since I no longer have the fusible link on that wire, what was it from the factory? I really wish all of these wiring diagrams I have, like for the 73, included the wire gauge and fusible link info.

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Yes, the #37 Yellow is the primary feed for the car. The auxiliary feed for optional accessories is black w/yellow dots that travels over the P/S shock tower to the firewall by the driver's left foot.

The fusible link gauge is imprinted on the molded rubber flag by the ring terminal. I'm sure @midlife can answer the question of what gauge the wire and fusible link are. 

 

 

 

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Ok, so not laughing. I made a drawing of the primary power feeds, to integrate the 73 with the 87. Here is my first schematic:

13A8E1FC-A5B6-4F5B-8654-D63C0B81209F.thumb.jpeg.4b861006e552c19df4db06125f516dd3.jpeg

I know it’s difficult to read. I’m using a 5 segment (3/8” bolts) strip panel to have a few locations for the Hot At All Times feeds (positive battery links), and a 6 fuse/relay box recommended by someone here or at another Mustang Forum. I believe I only need 2 of the relays in addition to the two the 87 system uses (ECU power and Fuel Pump). One for the HEGO (heated Ox Sensors) and a general power for other ECU related devices that might put a strain on the ignition circuit (coil, TFI, switch power to the ECU relay).

I also tried to indicate the color of the wiring from either of the vehicles, maybe I should identify which wire is from which vehicle? I didn’t identify the color of the wiring from the “start” or the NSS (I have an automatic). I’ll add that once I look it up.

Please look this over, once you stop laughing, to see if you can identify any major flaws in the design, things missing, things with ? Appreciate the look.

Steve

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I use as much of the donor vehicle wiring harnesses as possible, including fuses and relays. However, the way you're doing it should work out.

One thing I noticed is that it appears you are combining the run and accessory circuits. They are separate circuits and contacts at the ignition switch, #16 red/light green stripe for ignition, #297 black with green hash for the accessory circuits.  When you have the key in the accessory position, if you combine them, the ECU and fuel pump will be activated.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Yea, sorry to miss your first sentence. As a matter of practice, I choose not to disturb the 73 wiring. I was hoping the integration would be as minimal as possible, allowing me to add the 87 system, and eliminate any duplicated 73 engine system the 87 had. So almost all of the engine harness, less the lighting, horn, etc was extracted at the harnesses plugs. I hope to get some of those plugs so they don’t remain open, as a function of tityness.

So, since I made that decision, it required some fuse/relays, but as you see, not much. Thanks again. Steve

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The red with light green tracer is the correct wire for run only. It is also likely the same color for the T-Bird wiring for the ignition/EEC relay. For the most part the same colors were used across many years and Ford vehicle lines.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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That fusible link wire is 14 gauge. Fusible links are specified by gauge, not amps.

Edit: FYI, the fusing current of 14 gauge copper wire is approximately 160 amps, depending on the temperature of the wire.

Edited by Don C

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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