The "gauge doesn't work" how?
The sending unit (6 or 12 volt) is zero ohms empty and 30 ohms full.
Quick troubleshooting involves ...
... if the gauge reads full with a less than full tank ...
....... remove the wire at the sending unit
....... with the key on touch the wire to a good ground
...........if the gauge goes to empty the sending unit is either defective or does not have a good ground
.......... if the gauge stays full
.............. use a jumper wire to ground the terminal of the gauge to sending unit wire on the back of the gauge
..................if the gauge goes to empty the wire from gauge to sending unit is faulty - replace it
..................if the gauge stays full the gauge is bad
... if the gauge reads empty with more than an empty tank
....... remove the wire at the sending unit, turn the key on
.......... if the gauge goes to full the sending unit is bad - replace it
.......... if the gauge stays empty remove the wire from the back of the gauge that goes to sending unit
.............. if the gauge goes to full replace the wire from the back of the gauge to the sending unit
.............. if the gauge stays empty
................. check for 12 volts on the other terminal on the back of the gas gauge
.................... if 12 volts, the gauge is faulty - replace it
.................... if not 12 volts go find out why
Last edited by Bill Hanlon; 04/22/2025 10:20 PM.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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