Monitor Description

The ECM continuously monitors its internal circuits. This self-check insures that the ECM is functioning properly. If a malfunction is detected, the ECM will set the appropriate DTC and illuminate the MIL.

The two CPUs, main and sub CPU inside the ECM, perform continuous mutual monitoring. If there is difference between outputs from the two CPUs that deviates from standard level ranges, the ECM concludes that there is a fault and sets a DTC.