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Testing for a inoperative fuel gauge sending unit


I recently came up with a simple way to test the sending unit without removing it or the tank.
 The resistor portion of a spare headlamp switch can be attached with alligator clips between the wire for the sending unit & the ground wire. When the knob is turned (which would originally dim the dash lights) the gas gauge will move from E-F & vice versa if the sending unit is bad, but the rest of the system is all working correctly. If the gauge doesn't move, additional investigation of the wiring &/or the gauge is in order.
 I had an inoperative fuel gauge & wasn't sure if I should start under the vehicle or in the dashboard. This took about 15 minutes to rig up & saved a whole lot of time (the gauge was able to be controlled by the dimmer switch) since I didn't start at the dashboard  ;)
Hope this helps someone someday, Lorne

Most factory units are 0-90Ω so any good variable resistor in that range will do the trick, just make sure the other terminal on your potentiometer is connected to a good clean ground.


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