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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 33 (Engine Controls - Tests W/Codes - 3.8L) >> Self-Diagnostic Tests >> Test NTC-8A - Checking Oxygen (O2) Sensor Heater

Test NTC-8A - Checking Oxygen (O2) Sensor Heater

WARNING: This page is about a different car, the 1995 Plymouth Voyager, 1995 Plymouth Grand Voyager, 1995 Dodge Grand Caravan, 1995 Dodge Caravan, and 1995 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition on. Using scan tool, actuate Auto Shutdown (ASD) fuel system. Wait 2 minutes for O2 sensor to stabilize. Using scan tool, read O2 sensor voltage. If voltage is 0.4-0.6 volt, system is functioning properly. Test is complete.
  2. If voltage is not 0.4-0.6 volt, disconnect O2 sensor connector. Ensure scan tool is still actuating ASD fuel system. Using scan tool in voltmeter mode, check voltage on O2 sensor connector, ASD relay output circuit (Dark Green/Orange wire). If voltage is less than 10 volts, repair open Dark Green/Orange wire. Perform TEST VER-2.
  3. If voltage is more than 10 volts, stop actuation test. Using scan tool in ohmmeter mode, check resistance of O2 sensor connector, ground circuit (Black wire). If resistance is more than 5 ohms, repair open Black wire. Perform TEST VER-2. If resistance is less than 5 ohms, replace O2 sensor. Perform TEST VER-2.
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