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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Engine Controls - Tests W/Codes - 5.2L CNG) >> Self-Diagnostic Tests >> Test NTC-8B - Checking Oxygen Sensor Switching

Test NTC-8B - Checking Oxygen Sensor Switching

WARNING: This page is about a different car, the 1995 Dodge Ram Wagon, 1995 Dodge Ram Van, 1995 Dodge Pickup, and 1995 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
  1. Operate engine at idle. Check engine for any abnormal vacuum conditions. Repair any abnormal vacuum conditions as necessary. Perform TEST VER-2. If no abnormal vacuum conditions are present, using scan tool, read Oxygen Sensor (O2S) signal voltage. If voltage is more than 0.1 volt, go to step 3).
  2. If voltage is less than 0.1 volt, turn ignition off. Disconnect O2S connector. Disconnect Powertrain Control Module (PCM) connector. Using scan tool in ohmmeter mode, check resistance of O2S connector, O2S signal circuit (Black/Dark Green wire). If resistance is less than 5 ohms, repair short to ground in Black/Dark Green wire or Dark Green/White wire. Perform TEST VER-2. If resistance is more than 5 ohms, replace O2S. Perform TEST VER-2.
  3. Turn ignition off. Replace O2S. Turn ignition on. Using scan tool, reset adaptive fuel memory. Start engine and allow it to reach normal operating temperature. Using scan tool, read O2S state. Is O2S switches, test is compete. Perform TEST VER-2. If O2S does not switch, go to TEST NTC-15A.
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