Stray yellow wires near transmission

[Firepower]

Please help electrical gurus. ‘73 240Z.  Found two cut off wires on body near the middle of trans. Both yellow, no stripe codes.   I though they could be  the reverse lamp switch, but that’s wired up & working.

i pulled on the wires and they’re male spade connectors on the side that were cut (not by me obv).  Leaving behind two factory female spade connectors in plastic tubes. Any idea?  I couldn’t find anything on the wiring diagram that made sense to me. Thanks in advance.  -R

Edited March 6, 2020 by Firepower
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[grannyknot]

I'm no electrical guru but that kind of sounds like the wires to the seat sensor that lights up the Fasten Seat Belts indicator.

[SteveJ]

I would not be surprised if the car started out its life as an automatic transmission car. That would indicate that the wires would be for a neutral safety switch. Assuming the car is starting now, that would indicate the circuit for that switch was bypassed during the swap.

[240260280]

I'm with Steve and actually am working on a 1973 with the same stray automatic wires next to the manual transmission.

[Firepower]

I don’t think this was an automatic car at production.  The engine only ever had parts & emission controls that would be on a manual.

The “Seat Belt sensor” for passenger looks like the likely source. I didn’t cut the passenger wires, but have disabled the annoying buzzer & light within a year of buying the car. BTW- the power source for the light/buzzer is a useful way to get power when you are in the car AND have the key in the ignition (with the seatbelt unbuckled).  If you jumper the seat sensor to be always closed, it’s an interestingly switched ignition +12v source.  Maybe a dash camera or a radar sensor?

I’ll trace the wire harness back, when I get a chance and post my results here.  -R

[240260280]

Are you talking under the car or in the cabin?

[Firepower]

Connectors hang under the car, right next to the middle of the tranny on the passenger side.  Comes out of the stock harness on yellow spade connectors.   I think it goes up under the ‘dog leg’ panel and connects to the passenger seat pressure sensor.  Switch is called ‘STEP LRH’ on the wiring diagrams.  But of course you can twist the two switch wires together, and tap into the circuit at the seatbelt buzzer (or light).  If that’s what they are. I’ll update later when I get back to electrical connectors. 

Edited March 6, 2020 by Firepower

[Zed Head]

What happens if you connect the two wires?  If it's a switch, then something should light up or buzz or something.  I seem to recall also, that the "top gear" vacuum advance function was actually introduced before EFI.  It's an emissions function and 73 was one of the first emissions vehicles.  Might be a top gear switch.

[Zed Head]

Look at at 30, 31 and 32 here - http://www.carpartsmanual.com/datsun/Z-1969-1978/power-train/transmission-case/4-speed/from-sep-71

[w3wilkes]

A little OT, Interesting... If it's seat belt buzzer/light... When I bought my 73 new I figured I'd use it to train me to start using a seat belt. Worked! It's now automatic, I fasten my belt before any car I'm in goes in gear. As I recall from my 73 it only buzzes when in gear. 

[cgsheen1]

19 hours ago, w3wilkes said:

 As I recall from my 73 it only buzzes when in gear. 

Yup, I just had a late '72 in the shop with a working seat beat buzzer (first I've ever seen working (in a 240Z)...). Definitely has a neutral switch. The buzzer was active (while the seat belt was in the retractor) if the transmission was in any gear (including reverse) - off while in neutral. I'd vote for the OP's wires to be for the neutral switch.

Edited March 7, 2020 by cgsheen1