Gas Gauge reads Full all the time?....I wish

[canada karl]

If the gauge is constantly reading full is the problem likely the gauge or the sending unit?

[Mike W.]

I'd say sending unit or wiring. IIRC it's supposed to be something like 82 ohms, but I forget if that's empty or full. My guess is the circuit is either shorted or open. Unplug it from the sending unit and see what happens.

[canada karl]

At the sending unit in the trunk are 3 wires. Not sure which one does what. There should be 82 ohms to which wire(s)?

[Mike W.]

The sending unit itself should read ~82 ohms, not the wiring. It would be between the brown and one of the other wires. Brown is ground, like always, one lead is for the contact, it's a contact, think switch for the low fuel light, and the other is for the gauge. Both brown and the gauge wire have to be connected. At less than a full tank the resistance would be somewhere between 82 and zero.