Start engine and warm to operating temperature. Ensure idle speed and timing are adjusted to specification. Monitor Green LED on ECU while increasing engine speed to about 2000 RPM for 2 minutes under no-load condition.
Note the number of flashes by Green LED every 10 seconds. See ECU GREEN LED FEEDBACK RESPONSE table. Number of flashes during a 10-second period should at least equal number of flashes listed in table.
Race engine 2 or 3 times and allow to idle. Enter self-diagnostic Mode II. Disconnect throttle sensor/switch harness connector. Monitor Red LED and Green LED while idling. Red LED and Green LED should flash simultaneously. If not, adjust airflow meter (if adjustable). See ADJUSTMENTS article.
If airflow meter adjustment does not affect the LEDs, and ECU self-diagnostic system only flashes Code 55 (pass), either airflow meter, oxygen sensor or ECU is defective.

ECU GREEN LED FEEDBACK RESPONSE

Application

⁽¹⁾ Flashes (@ 2000 RPM)

Axxess & 240SX

⁽¹⁾	Number of flashes in 10-second period.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Feedback System