Continuous Self-Test

PURPOSE
During normal engine operation this self-test checks the Electronic Engine Controls (EEC) system by continuously testing memory integrity and processing capability, and verifying that associated sensors and actuators are connected and operating properly.


OPERATION
Continuous self-test is performed during all normal vehicle operation and stores any fault information as a continuous memory Diagnostic Trouble Code (DTC) in the Keep Alive Memory (KAM) for retrieval at a late time.

Generally, checks are made only for open or shorted circuits. In a few cases, improper sensor readings are noted. For example, if a coolant temperature sensor should change from cold to hot to cold in too short a period of time, an error is noted.


When the number of errors in a given time period exceeds a pre-determined number, that code is stored in KAM. This means that the error will have to be seen several times by the computer before it will register. This helps prevent codes from being incorrectly set on components that are actually good.

Retrieving Continuous Memory Codes
Continuous memory DTCs are retrieved by initiating a Key On Engine Off (KOEO) self-test. Key On Engine Off (KOEO) Self Test

Clearing Continuous Memory Codes
Continuous fault codes can also be manually erased by opening the STI circuit while codes are being displayed. Clearing Diagnostic Trouble Codes

Automatic Clearing of DTCs
Codes indicating faults that have not occurred in 40-80 engine warm-up cycles are automatically erased from KAM.