Fiat Ducato Diesel fuel tank monitoring on Cerbo GX

DIY
,
1

Adding diesel fuel level monitoring to a Fiat Ducato based motorhome. I ran a Twin cable from the tank level sensor to tank input 1 on the cerbo. Deemed necessary after swapping the combi boiler to a diesel unit especially to add an alarm function when getting low on fuel.This was simply parralled in to the sender output ( pink/red being the reading wire on my X244) Issue was i noticed the fuel gauge dropped ever so slightly when i connected the plug into the cerbo. Also when the ignition was on the cerbo displayed OpenCircuit.

I changed the way it was wired. Cut the pink/red and joined to the twin 14 strand cable. took that to the relay 2 input , common and normally closed. wired the tank 1 to the normally open and chassis ground. renamed the relay to Fuel Gauge. Now when i toggle the relay i get 0% or a true reading on the cerbo and empty with fuel light flashing or a reading on the Fiat dash. The cable has added approx 1.5 ohms resistance into the circuit which will have affected the reading slightly bit the senders range is high …300 to 12 ohms empty to full.

This works but is it the best way to do it? Am i missing something?

2

Your solution is the simplest way to have two gauges reading one resistive sender. These work by passing a current to the sender and reading the voltage drop. If you have 2 gauges then they are both trying to power the sender and the results are wrong.

You can get signal splitter for running one level sender with 2 gauges, but I have no idea if one is available for your install. Search Google for “resistive level sender splitter”