Oxygen Sensor: Testing and Inspection

INSPECTION

1. Turn Ignition switch off. Connect the test harness between the Programmed Fuel Injection Electronic Control Module (PGM-FI ECM) and harness connector. Wait at least two minutes.

PGM-FI ECM Connector Description And Wire Location:

2. Connect a jumper wire between terminal A6 and terminal A26.
3. Turn ignition switch on. Immediately measure voltage between terminals D14 (+) and A26 (-) as soon as ignition switch is turned on. Voltage should start at 0.4 - 0.5 volts when switch is first turned on, then decrease to below 0.1 volts in less than two minutes.
4. If initial voltage is 0.1 volt or less, disconnect the four pin connector from the Heated Oxygen Sensor (HO2S).
^ If voltage now reads more than 1.0 volt, replace HO2S.
^ If voltage now reads 1.0 volt or less substitute known good PGM-FI ECM and retest.
^ If components test OK, check for opens or shorts in WHITE wire between PGM-FI ECM terminal D14 and HO2S four pin connector, also GREEN/WHITE wire between PGM-FI ECM terminal D22 and HO2S four pin connector.