Electronic Control Systems: Self-Diagnosis

The PCM detects the failure of a signal from a sensor or from another control unit and stores a Pending DTC or a Confirmed DTC. Depending on the failure, a Confirmed DTC is stored in either the first or the second drive cycle. When a Confirmed DTC is stored, the PCM turns on the malfunction indicator lamp (MIL) by a signal sent to the gauge via F-CAN.

• One Drive Cycle Detection Method 

  When an abnormality occurs in the signal from a sensor or from another control unit, the PCM stores a Confirmed DTC and turns on the MIL immediately.

• Two Drive Cycle Detection Method 

  When an abnormality occurs in the signal from a sensor or from another control unit in the first drive cycle, the PCM stores a Pending DTC. The MIL does not come on at this time. If the failure continues in the second drive cycle, the PCM stores a Confirmed DTC and turns on the MIL.