Technical Wiring fuel sender?

[Henke100]

Hi!

I have replaced the fuel tank on my 126 from 1975. I also replaced the fuel gauge sender unit. Before this my fuel gauge had no signal and was at empty no matter what fuel level. After, the gauge jumped up to full even though the tank is empty. The fuel sender unit has two wire connections. Would this happen if I mixed them up? My belief is that they just present a resistance and it should not matter to which terminal the wires are connected?

Could this happen if the tank has poor ground?

All the best

Henrik.

 

[minijohn]

One terminal is for the low fuel warning light, the other is for the fuel level gauge.
One is an on/off switch, the other is a resistance.

The wiring diagram shows the wire colour is light blue/yellow for the gauge and grey/red for the warning light.
If you have letters next to the terminals on the sender unit, "W" is for the warning light, "T" is for the fuel level gauge.

If you swap the wires to the other terminals - that will probably cure the problem

 

[Henke100]

One terminal is for the low fuel warning light, the other is for the fuel level gauge.
One is an on/off switch, the other is a resistance.

The wiring diagram shows the wire colour is light blue/yellow for the gauge and grey/red for the warning light.
If you have letters next to the terminals on the sender unit, "W" is for the warning light, "T" is for the fuel level gauge.

If you swap the wires to the other terminals - that will probably cure the problem

Thanks, that was the problem. I switched places of those pins in the connector at the instrument board and it works as it should.

I had a wiring diagram which only showed one wire to the fuel level sensor.

Thanks again!

Henrik.