How to test a sender (fuel / water / holding tank)

Not sure if it's the sender or the gauge that has stopped working?

If the the gauge is showing the full range of movement then it is probable the sender is at fault. 

You can check the range of movement on a gauge by disconnecting the sender wire and then touching it to battery negative.  The needle should go all the way to full and empty if it is working.

You can test any of our resistance senders the same way whether you have a fuel / water / or holding tank sender.

To test the sender simply:

  • Disconnect the two wires on top of the sender.

  • Remove the sender from the tank.

  • Connect the wires on the sender to a multimeter.

  • Set the multimeter to resistance [Ω ohms]

  • Move the float to the top of the sender and take a reading on the multimeter:

  • At the top of the sender (full) the resistance should be:

    • European specification - 190 ohms

    • American specification - 30 ohms

  • Move the float to the bottom of the sender and take a second reading:

    • At the bottom of the sender (empty) the resistance should be:

      • European specification - 0 ohms

      • American specification - 240 ohms 

 

If you don't get the expected resistance reading on the multimeter then the sender is at fault and will need replacing.