Testing with Green Lamp Function
- The Green lamp function on the digital code checker is used to test O2 sensor signal. Different Green light modes indicate proper or improper mixture ratios as sensed by the O2 sensor. Before testing O2 sensor, disconnect neutral switch connector. Start and run engine at idle speed. Disconnect throttle sensor connector. See Fig 2 . Digital code checker should read Code 6 with Green lamp on.
- Increase engine speed to 2500-3000 RPM. Check that Green light starts to flash within 10 seconds after increasing engine speed. Code 6 should still be read with Green light flashing more than 8 times per 10 seconds.
- Maintain engine speed at 2500-3000 RPM. Disconnect O2 sensor connector. See Figure . Digital code checker should read Code 5. Green lamp should be on but not flashing. If any deviation from normal, see appropriate DIGITAL CHECKER CODE ILLUMINATION chart for possible causes.
- Mazda recommends using an Adapter Harness (499200163) and Engine Signal Monitor (499200162). The harness adapter is plugged between control unit and harness so that the engine signal monitor can display the circuit voltage at control unit.
- If the special tester is not available, the circuit checks may be performed by carefully backprobing each suspected wire (circuit) at the control unit. Ensure the engine is warmed to operating temperature.
- If voltage is not as indicated, check all related wiring, connectors, grounds and components. Repair or replace circuits as necessary.
- Repeat GREEN LAMP FUNCTION (O2 feedback control) test. Verify control unit is working correctly. If no trouble codes or circuit problems are found, problem may be intermittent. Drive vehicle and/or try to create conditions which cause problem to be present.
- If a driveability symptom is present and all circuits test good and no codes present, problem may not be computer related. Ensure all systems and devices not computer controlled are in good working order. If still no problem found, control unit may be bad.