Hello, I’m a novice and learning as I go on my 1970 240z. This pic shows a wire attached to the water temp thermal transmitter; but I cannot identify the other unused wire…FSM indicates it could be the water temp switch? There are no other obvious connections in that area. Thank you, Mike

What color is it?  Do you have a meter or test light?  See if it has power.

Automatic or manual transmission?

I think it goes to the small condenser on the side of the distributor.

Edited June 18, 20213 yr by CanTechZ

I have a manual transmission. The wire is hot when the ignition is on. I don’t have a condenser on the distributor; and  closest condenser is on the ignition coil.

Thank you again.

…and it’s a black wire. Thanks

Nissan liked to ground circuits to the block to complete them and pass current through whatever device they were operating, like the water temperature gauge.  Do you have the FSM page number describing the water temp switch?  

 

Yes, it’s page 40, Fig 2.8. I can’t find it on carpartsmanual.com. Also, my Z had electronic ignition when I bought it. Thank you again.

17 minutes ago, DedZed said:

Yes, it’s page 40, Fig 2.8. I can’t find it on carpartsmanual.com. Also, my Z had electronic ignition when I bought it. Thank you again.

That's not how the Factory Service Manual (FSM) displays their page numbers or figures.  Not sure what you're looking at.

Here's a couple from the FSM, showing a page number and a figure label.

 

Edited June 18, 20213 yr by Zed Head

Well, I learned a valuable lesson…I don’t have the FSM; and so I will download a copy and do better research. I’m embarrassed….

Is it a Haynes manual?  Page 38 might still show something if you take a picture and post it. 

You could also follow the wire back and find the device that is being supplied current.  Good to know that it has power though, keep the end insulated.

Here's the site's FSM download area.

https://www.classiczcars.com/files/category/11-240z/

Thank you for your insight!

12 hours ago, DedZed said:

I have a manual transmission. The wire is hot when the ignition is on. I don’t have a condenser on the distributor; and  closest condenser is on the ignition coil.

Thank you again.

You mentioned that your car has been changed to electronic ignition, likely changes were made and that black wire is not used. Normally there are two condensers, one at the coil and one at the dizzy for the points circuit, at least that is how my 1970 is. Here is a picture of mine with the dist. cap removed. showing the connector spade (red arrow) where the black wire goes.

FYI it's the yellow wire that is connected to the temperature switch on the thermostat housing.

In your picture I see red and black wires in the same area where mine has the condenser. Do these connect to the electronic ignition module? This would explain why there is no place to connect the original black wire.