NSS related question

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SteveO_71

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Do they sell a neutral safety switch specifically for the 71 C6 trans? I see them listed for 72, 73 or C6 for some other vehicle i.e. bronco. Can these be used?
Mine has one cable with a 4 connector end.
 

Doug's 73 Mach1

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The neutral safety switch is built into the floor shifter wiring harness. It is the same for all Mustang automatics, C6 or otherwise.
 

SteveO_71

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Well when I'm looking at the drivers side of my C6 351c, it appears to be mounted in that location. Were some mounted at the trans as opposed to the console?

And back to my original question, which one should I use?
 

Doug's 73 Mach1

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I used to have a 71 with a C6. It had no wiring at the transmission, only on the shifter under the PRNDL bezel. The wiring there was for Neutral safety, back up lights, and illumination.
 
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I have a 72 with a c6 and it’s mounted on the driver side of the trans. I bought a new one from NPD I believe, it’s been awhile. I don’t know what would be different between 71/72, but maybe a different wire configuration?
 

midlife

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I have a 72 with a c6 and it’s mounted on the driver side of the trans. I bought a new one from NPD I believe, it’s been awhile. I don’t know what would be different between 71/72, but maybe a different wire configuration?
The middle of 72 had the addition of the seat belt reminder light wiring.
 

SteveO_71

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The one for the 72 has 2 connectors. So, just dont connect one although the connectors look different?
Here is one for a Bronco C6 where the connector looks like the one I have. The squarish 4 pin connector. Would that work?

I remember reading on here or another mustang site where someone was asking the same question for a 71 but now, cant seem to find it.

 

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The neutral safety switch is built into the floor shifter wiring harness. It is the same for all Mustang automatics, C6 or otherwise.
Not on my 3 - 1973 cars. 2 Mach I's with C6 have transmission mounted switch and also our 1973 convertible with 352C and C6
 
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Regarding some NSS having 4 wires, and some having 6 wires, there is an explanation. But, to the question ask re: if a 6 wire MSS can be used instead of a 4 wire NSS, the answer is "yes." But it bears an explanation.

In the early 70s our federal government decided we needed to be saved from out own stupidity, and there may be a valid premise for that. They required car manufacturers to have a Seatbelt Interlock system for at least 1973, maybe 1972 cars. They were miserable systems, and caused a lot of frustration. There was such a loud cry that the federal government rescinded the new legislation and allows consumers and shops to disable the Interlock circuitry that was supposed to save us from being stupid.

Anyway on both the 4 and 6 wire NSS units 2 of the wires are for the Neutral Safety Switch. Two other wires are for the Backup Lamp Switch. And the last 2 wires are for (you guessed it) the Interlock circuit. Since your Interlock is no doubt not being used there is no need to plug the Interlock related wires and plug into anything. Just wire tie is out of the way and you are good.

Attached is a colorized electrical schematic snippet showing the circuitry involved.

If you run into pinch post the concern in this forum, or email me at [email protected].
 

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  • 1973Mustang_SeatbeltInterlockCircuitry_20210608.pdf
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carguy47

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There appear to be several versions in aftermarket format, as well as some used ones out there.
C6 and C4 have the option for transmounted, FMX shifter version.
 

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Doug's 73 Mach1

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Here is a photo of a 5 wire version plus a short black ground lead for the PRNDL illumination light.

IMG_1397[1].JPG
 

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