Code 22
- Turn ignition switch off. Connect a voltmeter to the Green oxygen solenoid wire at the carburetor 6-wire connector and ground. Disconnect and plug vacuum hose at the computer. Connect an auxiliary vacuum supply to the computer and apply 14 in. Hg vacuum.
- Connect a tachometer to the engine. Disconnect the oxygen system test connector and then reconnect Green with White tracer wire only. If equipped with a manual transmission, disconnect the speed sensor connector. Stick a straight pin into wire of cavity No. 5 of the computer 10-wire connector.
- Connect a jumper wire between the straight pin and the White with Orange tracer wire of the speed sensor harness connector. Start engine and wait one minute. Raise engine speed to 2000 RPM. Hold oxygen system test connector (open terminal) with one hand and touch the battery positive terminal with the other hand. If voltmeter reading decreases to 0 volts, go to step 4). If voltage does not decrease, go to step 6).
- Check oxygen sensor. With voltmeter connected to oxygen solenoid Green wire, disconnect hose at computer and plug. Apply 14 in. Hg of vacuum to computer. Connect tachometer to engine and run engine to 2000 RPM.
- Reconnect oxygen test connector. Wait a few seconds for oxygen system to start working. If voltmeter reading pulsates between 7 and 14 volts, go to step 6). If voltage is below 7 volts, go to step 7).
- Check oxygen feedback system for a rich condition. Connect voltmeter to oxygen solenoid Green wire. Disconnect hose at computer and plug. Apply 14 in. Hg of vacuum to computer. Connect tachometer to engine and run engine to 2000 RPM. Disconnect oxygen test connector. If voltmeter reading decreases to 0 volt, oxygen system is okay. If voltage does not decrease, check oxygen sensor wire for an open circuit to test connector. Repair system as necessary. If there's no open circuit, replace oxygen sensor.
- Run engine at 2000 RPM with 14 in. Hg of vacuum applied to computer. Disconnect hose from PCV valve and cover orifice. Allow air to slowly enter orifice. If voltmeter reading should increase toward 14 volts, oxygen system is okay. If voltage does not increase, check the oxygen sensor wire for a short circuit to the test connector. If there's an open circuit, repair system. If there's no short circuit, replace oxygen sensor.
- Check oxygen feedback system for a lean condition. Connect Green with White tracer wire and disconnect oxygen system test connector. Let engine return to idle speed and then turn off engine. Disconnect computer 14-wire connector. Connect an ohmmeter between test connector (Black wire) on computer side and cavity No. 10 of the 14-wire connector. If ohmmeter shows continuity, replace computer. If there's no continuity, repair open wire to test connector.