Introduction

Fig. 52 ECCS Modes:

Nissan uses a self-diagnostic system has five different functions or "modes". Each mode does a specific type of test.

1. Mode 1 is the normal operating mode that the ECCS system is in whenever the key is on and no other modes have been entered. Monitoring of the 02 sensor is done in this mode.
2. Mode 2 is used to monitor how well the air/fuel mixture stays at the factory setting.
3. Mode 3 is used for extracting stored trouble codes.
4. Mode 4 is used to check the operation of the on/off type switches:

^ Vehicle Speed Sensor
^ Idle Switch
^ Starter Switch

5. Mode 5 is the real time diagnosis system. It will detect failures in the following circuits at the exact moment they are present and output the appropriate code:

^ Crank Angle Sensor
^ Ignition Signal
^ Air Flow Meter
^ Fuel Pump

Switching Diagnostics Modes:

Modes are manually switched. Refer to the chart for mode switching details.

TECH TIPS:
All the modes of the Nissan Self-Diagnostics can help you fix cars faster once you get used to how everything works. But for quick checks, Mode 2 and Mode 3 are where you want to go first. Do a quick check in Mode 2 and make sure the Oxygen Sensor and Mixture are OK and then check for stored codes in Mode 3.