ECM Function

The ECM can supply 5V or 12V to various sensors or switches. This is done through pull-up resistors to regulated power supplies within the ECM. During testing, a digital multimeter (DMM) with at least 10 megaohms input impedance is required in order to ensure accurate voltage readings.

The ECM controls the output circuits by controlling the ground or the voltage circuit through transistors or a device called a high side or low side driver.