Fuel & Oil Gauge Wiring.

Jim, Trying to contact you about recertification process. Thanks, Tim

Jim with the cardboard domed the long contacts inside the switch were touching the metal case. Hot water and some gentle pressure flattened the dome and it is holding it's shape.
Attached is a sketch of the wiring diagram.

Terry - Most of the one's I've seen are domed. As long as the switch still works it's OK.

Gary - the missing terminal is usually because someone pushes the switch too hard and breaks it. It only takes about 1/8" to gently push the button and make the switch work. 

Thanks Jim and Terry for this great explanation of the gas / oil gauge and wiring. My gauge lost one of the connectors on the back side many years ago. I have seen many also missing the same piece. I suspect it was a manufacturing defect 90 years ago.


Gary Parsons

Hi Jim.
I ended up dismantling the switch. The contacts needed cleaning and the main cardboard disc had become dome shaped. I tried putting the disc complete with the contact in very hot water then pressed the dome flat. I considered making a new phenolic disc to replace the cardboard but that would have been making a mountain out of it all. The switch is working and needs to be refitted. With a magnifying glass I was able to see Oil, Gas and Gauge in the cardboard disc ...... Amazing!
Thanks again for your help.

Hi Terry,

Check your switch with an ohm meter. The one I working on today had 20 ohms across the NC terminals and 70 ohms across the NO terminals. This will throw the readings way off. I had to pull the switch apart and clean the contacts. Very easy to do. The trick is not breaking the tabs that hold the cardboard back in place. I broke them so I soldered them back in place when I was done.

All is well here... I hope you are too. Have a Happy and Healthy New Year... and lots of Effortless Motoring!!!
Jim

Thanks Jim, the fuel & oil gauge had never worked properly. During the resto I reconnected the wires as they had come off the car. Now I have a better understanding of how it should work. I will have a go at it later today or tomorrow. Hope all is well with you and your family.
Happy New year mate,
Terry

Hi Terry,
Funny you should ask - I just wired this up 2 hours ago.

The cardboard on the back of the switch was originally marked - Gauge, Oil, Gas(?). If you can still see the marking it should be straight forward - Gauge goes to the #1 terminal on your sketch, oil and gas go to their respective sending units.

If the switch isn't marked you are going to need to test the switch. There should be a common terminal, a normally open terminal and a normally closed terminal.  The common terminal (gauge) should be connected to the gauge - terminal #1 on your sketch. The normally closed terminal would go to the fuel tank sending unit and the normally open terminal would go to the oil level sender in the engine.

Have Fun,
Jim

Can anybody help with the correct wiring layout for the fuel and oil gauge?
Attached is an enlarged sketch taken from the complete wiring diagram this is shown first. 
The second sketch shows the layout of the gauge and the push button below it.
Any help would be appreciated.