Digitise an older engine - ESP32

[Techstyle]

@Boatingbaileys I found another problem and don't know if you face it: I would like to keep the analog temperature clock. If I followed your voltage divider correctly, what happened is that when I connect the ESP32 to the positive and negative of the temperature sensor, the clock rise to 120º.

You should be able to connect an INA219 board to either side of the analogue gage (Vin+ to the supply side, Vin- to the temp sender side), you do need to remove the 'R100' shunt resistor from the board - then you can use the INA219 as a voltage sensor and then use the following equation to get the resistance of the temp sensor:

R2= (VOUT * R1)/(VIN - VOUT)

where R2 is the Temp sensor resistance
Vout is Vin-
Vin is Vin+
R1 is the resistance of the analogue gage (measure with a multimeter with nothing connected)

you are basically checking the voltages in the existing voltage divider circuit where the gage is the other resistor.

I have yet to try this but it should work.

I have used these for my Battery monitor: https://amzn.to/45ZZ8ka