General Testing Description

The self-test is divided into three specialized tests, Key On/Engine Off, Engine Running, and Switch Monitor test. The self-test in not a conclusive test by itself, but it used as 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 or 4EAT system by testing its memory integrity and processing capability, and verifies that various sensors and actuators are connected and operating properly.
Unlike EEC-IV, no sensors or switches are exercised during the self-test. Also, intermittent codes are not erased if the fault is removed after 40 vehicle cycles. Therefore, any intermittent code will be stored in permanent memory until erased.