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Home >> Geo >> 1993 >> Tracker Base, 4WD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Fuel System >> Fuel Control >> Oxygen Sensor Heater
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Oxygen Sensor Heater

  1. With ignition off, disconnect electrical connector at oxygen sensor. Turn ignition on with engine off. Using voltmeter, check for battery voltage on Black/White wire at connector. If battery voltage exists, go to step 3).
  2. If battery voltage does not exist, check for open circuit in Black/White wire between oxygen sensor and 15-amp ignition/coil fuse. Fuse is located in fuse block on left side of steering column.
  3. Turn ignition off. Connect test light to battery voltage. Backprobe Pink wire at oxygen heater jumper connector and note if voltage exists. Jumper connector is taped to wiring harness near ECM, located under left side of instrument panel, near kick panel.
  4. If voltage exists, go to next step. If voltage does not exist, check for open circuit in Pink or Black wire to ground or defective Black wire in jumper connector.
  5. Using ohmmeter, measure oxygen sensor heater resistance between Pink and Black/White wire terminals of oxygen sensor. Resistance should be 3.7-5.1 ohms at 73°F (23°C).
  6. If resistance is as specified, heater portion of oxygen sensor is okay. Replace oxygen sensor if resistance is not as specified.
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