Another Mystery Connector Question

[MooseStang]

While tracking down my reverse light issue, I came across these connectors.
What are they for?
 

 

[RD-72]

The larger one looks like the neutral safety switch....this is on the firewall , drivers side center is, correct?

the smaller white one...I’m not entirely sure

i had to replace my neutral safety switch a few weeks ago...I had no reverse lights on my automatic c4

 

[RD-72]

Here is a picture of my old one. I had 2 male and 2 female connectors, so maybe this isn’t the one

 

[Hemikiller]

While tracking down my reverse light issue, I came across these connectors.
What are they for?
 View attachment 55910

Blue plug is for the 72-73 TRS switch on the side of the 4 speed. 

Black plug is the harness for the backup lights on a 3/4 speed, note the looped Lt Blue w/red stripe wire on the transmission side.

White plug is for the auto shifter illumination, it's present on all cars regardless of transmission. 

You can clean the wires with some Gojo hand cleaner, or the tubs of hand cleaner wipes, so you can see the wire colors and trace them down on the wiring diagrams. 

https://7173mustangs.com/wiki/

Most reverse light issues are a bad or misadjusted switch, or corroded sockets at the taillights. 

 

[midlife]

TRS switch?  Transmission Range Sensor?  I don't think so...the wires are hooked up to the seat belt relay system, IIRC.  I suspect the relay light lights up whenever the transmission comes out of park or neutral and into a gear.

 

[MooseStang]

I suppose I should have said this earlier, 4 speed manual.
Yeah, I did confirm that the black one is for the backup lights by jumping it, bingo, reverse lights are good, something is mucked up with switch.
I believe the call on the seat belt light may be correct, but I haven't located the associated wiring section yet.

 

[Hemikiller]

TRS switch?  Transmission Range Sensor?  I don't think so...the wires are hooked up to the seat belt relay system, IIRC.  I suspect the relay light lights up whenever the transmission comes out of park or neutral and into a gear.

Yep, my bad, that's exactly as Midlife stated. The TRS connector is a rectangular 2 place. Transmission Regulated Spark system, held off vacuum advance until the transmission was in top gear. 

 

[MooseStang]

Does the TRS apply to manual trans as well?   Points or Pertronix, or both?

 

[Hemikiller]

It was used in various applications, both auto and manual. FWIW, it's not really needed anymore and can be eliminated/disconnected.