Designing an Engine Oil Temperature Display Gauge Project

[17-CB-002]

Hi Csory, in my previous job at a Japanese automotive OEM and before the diagnostic scanners were available, we back probe the wire at either the ECM or sensor depending on ease of component access & location. We often leave it there for days during troubleshooting.
There is no need to worry about the "pull up" resistor if you are using a high impedance meter. The "pull up" resistor selection depends on the scale reading the engineers want to see inside the ECM.

You mention the "virtual" ground: Inside the ECM there are 3 types of ground. One for the "Input" sensors such EOT, Intake Air Temperature etc. then there is the "Output" device ground such as Injectors or the Idle speed control air valve, ignition timing etc. and the last ground is for the ECM internal circuitry. Then all these ground wires goes to the chassis.

Can you build a "look up table" that can read the EOT in voltage (between 0 & 5v) and display it in temperature C or F ?

Tomorrow, I will shoot a short video to demonstrate it using a Digital voltmeter on my bike.

Would it not be nice if we can read the real exact oil temperature especially if we are stuck in traffic!