An ECM ROM malfunction is detected by using a checksum technique for verifying data. Digital data is composed of zeros and ones. A checksum is the total of all ones in a string of data. By comparing the checksum value with a stored value, a malfunction can be detected. An ECM RAM malfunction is detected by writing a known string of data and comparing it with a stored string of data.
The ECM monitors RAM areas and communication connections between microcontroller and output drivers and sets DTC P0605 if failure is detected.
Item | Detecting Condition | Possible cause | |
Case1) | Monitoring Strategy | ● Signal check High ● Signal check Low ● Signal interruption ● Rationality check | ● Faulty ECM |
Case2) | |||
Case3) | |||
Case4) | |||
Threshold value | ● Each check sum of several blocks / Actual check ● sum ≠ check sum data | ||
Enable Conditions | ● Driving cycle | ||
Diagnostic Time | ● Once / drving | ||
MIL on condition |
