Description

Engine Control Module Self Test Description

1. Fault Code:
ECM Self Check Fault P0605

2. Monitoring Procedure
The ECM uses EEPROM to store long term-adapted values, tune set-up values and the diagnostic fault codes, freeze frame data etc. If the EEPROM becomes corrupted then the system cannot perform as designed. The ECM will then revert to default data to allow the vehicle to continue running. The EEPROM also stores a set of data, which holds the EEPROM_Calibration_Data. This data is used to determine whether the EEPROM has become corrupted. It is assumed that if this data is corrupt then the adaptive and tune data etc will also be corrupt.

The ECM attempts to restore data from two separate sets of locations in the EEPROM.
Each set of locations holds a copy of the entire set of data to be stored in EEPROM.

The ECM checks each piece of data it restores using a Cyclic Redundancy Check. If this check fails then the ECM will try to retrieve the copy of that piece of data from the alternative memory location. This data is also subjected to a cyclic redundancy check. If the second check fails then the system will use a default for this piece of data and copy it to both sets of locations.

If both sets of EEPROM_Calibration_Data Cyclic Redundancy Checks fail, then the system will recognize that there is an internal ECM fault present.

3. Primary Detection Parameter
The test uses stored digital data from several memory locations.

4. Fault Criteria Limits
Both sets of EEPROM_Calibration_Data retrieved from the EEPROM must fail the cyclic redundancy check.

5. Monitoring Conditions
The ECM always performs this test.

6. Monitoring Time Length / Frequency of Checks
The ECM performs the test immediately after power is restored from a dormant state. The test takes no more than 3 seconds to complete.

7. Criteria for Storing Fault Code
A fault code will be stored immediately if the ECM cannot retrieve valid data from the EEPROM.

8. Criteria for Illuminating MIL
The MIL will be illuminated immediately if the ECM cannot retrieve valid data from the EEPROM.

9. Criteria for Determining Out of Range Input Signals.
The data is subjected to a cyclic redundancy check.