I'm putting my 1970 car back together after, err, MANY years. There is a bronze 3-way relay hanging down from dashboard. I forgot to check where in dash this was actually coming from when we reinstalled the dash. It only has one attachment hole. Where would this attach to on my Z? Crawling around in there last night, I don't see a likely spot on bottom of dash, or on steering column. It might reach the driver side outside wall, didn't measure.

This site has a better picture than I do:
https://www.autopart3.com/products/70-71-72-73-datsun-240z-oem-miyamoto-japan-12-v-15-a-t-h-b-s-relay?srsltid=AfmBOoqlneK1uqgtUE9Hf75LHDaelmOV0N2L8L6tYn-KQUFck3YmOJX4&variant=43606986293482

Also, what exactly does this do?

I don't see it the 240z service manual, or on page 26 of the 1971 service supplement, but something that looks like it is unnamed on page 28, which page is labeled "1971 late model". This car btw has tons of non-original things in it due to a PO restore project some time around 1980.

@SteveJ Is this the horn relay?

The relay in the link is a horn relay. If the device @Warty is referring to is marked the same, he has found his horn relay.

To answer the question not asked:

H gets the solid green wire that goes out to the horns.

B gets the green/red wire that should have 12VDC+

S gets the green/black wire that goes to the steering column for the horn button.

Thanks folks!

Sounds like Horn Relay goes on driver side kick panel area. There is a bolt hole there I could imagine held this in place.

Nobody on BAT takes a picture of that area of the car.

Of course... If I had done a better job documenting this when I took apart the car bit by bit, I wouldn't need to spend hours scanning through BAT. ;)

I call that "tuition". The cost of learning. Ive rebuilt probably 40 assorted different cars. And every time we say "I didn't take enough pictures!"

9 hours ago, Patcon said:

I call that "tuition". The cost of learning. Ive rebuilt probably 40 assorted different cars. And every time we say "I didn't take enough pictures!"

What I enjoy about it is that in my head, I took enough pictures. So I'm always like "Oh, I know I got shots of that, let me check how that looked before" and then... nope. I suspect I will continue to pay this tuition for a long time.

Thanks Captain, that's the spot I was thinking of. Awesome.