1989 Nissan-Datsun Sentra BaseFACTORY OEM SERVICE PROCEDURE

Feedback System: Notes

  1. Start engine and warm to operating temperature. Ensure idle speed and timing are adjusted to specification. Increase engine speed to about 2000 RPM for 2 minutes under no-load condition. Monitor Green LED on ECU. With engine speed at 2000 RPM, Green LED should flash at least the appropriate number of times during a 10 second period. See GREEN LED FEEDBACK RESPONSE table in this article.
  2. Race engine 2 or 3 times and allow to idle. Enter self-diagnostic mode 2 and monitor and disconnect throttle sensor/switch harness connector. Monitor Red and Green LEDs while idling. Red and Green LEDs should flash simultaneously. If LEDs do not respond as described, adjust airflow meter (if adjustable). See ADJUSTMENTS article.
  3. If airflow meter adjustment does not affect LEDS, and ECU self-diagnostic system flashes only code 55 (pass), either airflow meter, oxygen sensor, or ECU is defective.
Factory Service Tools

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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.

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