Appendix:Self-Test Description

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24-01-91 Fuel System Diagnosis 24-01-91


APPENDIX: Self-Test Description


The Self-Test is divided into three specialized tests: Key On Engine Off Self-Test, Engine Running Self-Test, and Continuous Self-Test. The Self-Test is not a conclusive test by itself, but is used as a part of the functional Quick-Test diagnostic procedure. The processor stores the Self-Test program in its permanent memory. When activated, it checks the electronic engine control system by testing its memory integrity and processing capability, and verifies that various sensors and actuators are connected and operating properly.

KEY ON ENGINE OFF SELF-TEST

At this time, a test of electronic engine control system is conducted with power applied and engine at rest.

CONTINUOUS MEMORY CODES

Continuous memory codes are issued as a result of information stored during continuous SelfTest, and are kept in permanent memory until they are erased. These codes are displayed only during Key On Engine Off testing. These codes should be used for diagnosis only when MIL is not illuminated prior to testing or when codes cannot be duplicated after erasing.


ENGINE RUNNING SELF-TEST

At this time, a test of the electronic engine control system is conducted with the engine running. The sensors are checked under actual operating conditions and at normal operating temperatures.