New Fuel Gauge Circuit

[bytes311]

I don't switch the sender connection. I drive it with 5.0 volts through a resistor equal to the maximum sender resistance. Therefor I would read 2.50 volts on the green/black wire with full tank. (Some senders have the values swapped) I read the voltage on that green/black wire to determine the tank level. I guess you could switch that drive off and on to save a little power (10 ma. with a 250 ohm value at full and 17 ma. with the 40 ohm value at empty).

With the stock setup there is a lot more current flowing through the sender.

Thanks!

[FABombjoy]

You can PWM drive the gauge with an N-channel MOSFET. I'm using a ground-switched output on my Haltech to do the same thing. That might make the circuit simpler for arduino use.

I connect a 200-ohm resistor between the gauge sender to ground, and then the low-side driver to the gauge/resistor junction. If there is a circuit disconnect the needle points around the "E" in fuel letting you know there is an Error. Your output D/C isn't linear to gauge reading but a 4-point correction curve will get it close enough. Use the highest PWM you can for smoothest gauge movement. Then you can use a second MOSFET to trigger the low-fuel light at whatever measured fuel level you like.

For a sender I'm using a Dorman 55818 with a 2-part 3d printed adapter to set it in the stock sender hole. It's easier (imo) than fiddling around with the fuel module float arm kinematic ship in a bottle puzzle.