Diagnostic Self Test

The Diagnostic Test Mode for Electronic Engine Control (EEC) Quick Test is divided into three separate tests:

- Key On Engine Off (KOEO)
A test of the system is conducted with power applied and engine off.

- Key On Engine Running (KOER)
A test of the system is conducted with the engine running. The sensors are checked under actual operating conditions and at operating temperatures.

- Switch Monitor test
A test of the input switches made with the engine off and cool.

The self test is not a final test by itself, but a part of the functional check. The Powertrain Control Module (PCM) stores the self test program in its permanent memory. When activated, it checks the EEC system by testing memory integrity and processing capability, verifying various sensors and actuators are connected and operating properly.

The KOEO and KOER self tests are functional tests only, detecting faults present at the time of the self test.

The Switch Monitor test checks input signals sent from individual sensors and switches to the PCM.