I just finished getting my gas gauge to work (original GM). There should be about 30 ohms across the gauge posts withe the sender disconnected if I remember right. There should be 0 ohms between 1 post and the instrument case, and 30 between the other post and the case. I got wiring diagrams from the Old Car Manual Project.
On the original gauge, if the actual meter gets miss aligned in the case, it can short out... And burn many wires...
And if the gauge is a 6volt version, you need a reducer from your 12 volts or it won't work right.
I had to: Solder a hole in the float, install a voltage reducer and realign the meter in the case.
Current fleet (subject to change w/o notice) \'49 GMC 3/4-Ton , 60 Austin Healey Frog-eye Sprite (some assembly required), 2011 Dodge Avenger, 2015 Jeep Cherokee. No, they don't all run. My other ride is a (B737)no, (B767)no, A320.... Update... was Embraer E190, now Boeing B787. Knowledge is a wonderful thing, but ignorance means you don't know you can't do something.
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