Circuit Description

PCM detects inconsistencies between main CPU and Watchdog CPU software/calibration.

When DTC sets, PCM illuminates MIL as soon as fault was detected. PCM will store conditions present when DTC was set as FAILURE RECORDS data only.

PCM will turn MIL off on third consecutive trip cycle during which diagnostic runs and fault is no longer recognized. A history DTC will clear after 40 consecutive trip cycles during which diagnostic runs and fault is no longer recognized. DTC can be cleared with scan tool, or by disconnecting battery voltage feed to PCM.