DR-7A Fault Code 22-Oxygen Feedback System

1. Turn ignition switch Off.
2. Connect a voltmeter to the green oxygen solenoid wire at carburetor and ground.
3. Disconnect and plug vacuum hose at computer, then connect auxiliary vacuum supply to computer and apply 14 inches of vacuum.
4. Connect a tachometer to engine, then disconnect oxygen sensor connector.
5. Start engine and wait one minute, then raise engine speed to 2000 RPM.
6. Hold oxygen sensor harness terminal with one hand and touch the positive battery terminal with the other hand.
7. If voltmeter reading decreases toward 0, proceed to Step B. DR-7B Oxygen Feedback System Operation
8. If voltmeter reading does not decrease, proceed to Step E. DR-7E Oxygen Sensor Wire to Computer For Open