Diagnostic Mode

To enter the diagnostic mode, ensure key is on and engine is stopped. Ground diagnostic test terminal (Terminal "B"). System will flash a code 12, indicating that the ECM is operating properly and can recognize a system fault. Code 12 will flash until test terminal is ungrounded.

If test terminal is grounded with engine running, system will display any stored trouble codes by flashing check engine light. Each code will be flashed 3 times. Hard codes will be repeated each time key is turned off and engine restarted. Intermittent codes will disappear when key is turned off and engine is restarted.