Oil Temp not working 1971 Porsche 911

[Sam Bruni]

I have a 1971 Porsche 911 and can't get the oil temperature to come on. I put the engine back in it and I have a green wire that I believe might be the problem. On the diagram that our host has for my car, it shows the green wire is optional for a sportomatic, which my car was not. I assume if I can figure out where this wire goes, my temperature will come on. The black wire is hooked up to the oil temp sensor and goes into the wiring harness then to the 14 plug connector.

You can see the image below for the green wire that is just hanging there. Any help would be appreciated.

[timmy2]

Oil temp wire should be black going to position 3 of the main engine harness 14 pin connector. Check your 14 pin engine harness connector for the green/black wire in position number 3(Bottom row when installed second from the end furthest from the wire entry point) where it goes to the next 14 pin connector on the panel (Pin 3) and then back to the gauge through the main harness. The loose green wire shouldn't be for the oil temp.

[E Sully]

You are correct that the diagram shows the green wire for the sportmatic temperature gage. It was part of the standard wiring harness whether the sportmatic was installed or not. You should have the other end by the gage cluster.
As Dennis wrote, the wire on the engine harness to the engine temperature sender (56 in the diagram, part 2) is black, changing to Green/Black at the rear console connector to the gage in the dash.
Battery voltage is supplied to the gage by the Black/Red wire from the ignition switch, and the temperature sending unit is grounded to the engine. The resistance to ground varies by pressure at the sending unit, making the gage needle move to indicate pressure.

[Sam Bruni]

Thanks! I will do some investigating.