Entering Self-Diagnostics
- Turn ignition on, but leave engine off. Using a small screwdriver, turn diagnostic mode selector on ECU fully clockwise. Wait at least 2 seconds and then turn diagnostic mode selector fully counterclockwise. Mode II self-diagnostic will result and the CHECK ENGINE light and the Red LED inspection light will flash trouble codes (if present).
- If engine is started at this stage, the CHECK ENGINE light and the Red LED inspection light will display the condition of the air/fuel mixture which is monitored by the O2 sensor or if the system is in closed or open loop.