fuel gauge voltage drop

[ram250098]

I got my fuel gauge working, but I noticed when I put a meter on the back of the gauge I have 4.68 volts on one side and 3.68 volts on the other.
Does this mean the gauge is on the way out?
When I was testing the wires and connections behind the kick panel with a test light I noticed the gauge would rise when the test light was lit..I guess that just allows more current to flow.
AL

 

[72RoadrunnerGTX]

The gauges operate at around 5.5 volts as regulated by the gauge voltage limiter. The senders provide a varying resistance to ground, approximately 10-90 ohms, your test light is altering (reducing resistance to) the ground path, causing the gauge movement.

 

[ram250098]

Thanks I thought so, Maybe I will try another limiter and see if the voltage comes up to where it should be.
Thanks

 

[bigmanjbmopar]

I think it would take too long to explain ohm's law but basically when you touch a light probe to a resistance circuit you are basicly completing the circuit and making the gauge thing the resistance of the probe is like a full or empty reading. Best way to check fuel gauges is with a spare sending unit ground it to the car's frame with a jumper wire, and use the wire that is plugged into the tank sending unit and plug it into the spare and slowly raise the float and watch the gauge this with the Key in the on not started position. you will see it move to full and drop to empty, if not then make sure you are at a good ground and the wire at the unit is reading 5vdc if not then you have an issue with the wiring at the cluster or bulkhead. 99% of the time is a bad ground.

 

[ram250098]

Thanks, excellent idea with the sender, to bad I gave away my spare LOL
I think it turned out to be the connection at the circuit board.
AL