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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 35 (Engine Controls - Tests W/Codes - 3.9L) >> Self-Diagnostic Tests >> Test NTC-8B - Checking O2S Heater

Test NTC-8B - Checking O2S Heater

WARNING: This page is about a different car, the 1995 Dodge Ram Wagon, 1995 Dodge Ram Van, 1995 Dodge Pickup, 1995 Dodge Dakota, and 1995 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For circuit and connector terminal identification, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS  section at the end of this article.
  1. Turn ignition on. Using scan tool, actuate ASD fuel system. Wait 2 minutes for O2S voltage to stabilize. Using scan tool, read O2S voltage. If voltage is less than 4.8 volts, O2S is functioning properly. Test is complete. If voltage is more than 4.8 volts, go to next step.
  2. Disconnect O2S connector. Using scan tool in voltmeter mode, check voltage on O2S connector (harness side), ASD relay output circuit (Dark Green/Orange wire). If voltage is less than 10 volts, repair open in Dark Green/Orange wire or Orange/Dark Blue wire. Perform TEST VER-2.
  3. If voltage is more than 10 volts, use scan tool to stop ASD fuel system actuation. Using scan tool in ohmmeter mode, check resistance on O2S connector (harness side), heater ground (Black/White wire). If resistance is more than 5 ohms, repair open Black/White wire. Perform TEST VER-2. If resistance is less than 5 ohms, replace O2S. Perform TEST VER-2.
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