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Home >> Jeep >> 1995 >> Grand Cherokee Laredo, 5.2 Y, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 5.2L >> Self-Diagnostic Tests >> Test NTC-8B - Checking O2S Heater

Test NTC-8B - Checking O2S Heater

NOTE: For circuit and connector terminal identification, see CONNECTOR IDENTIFICATION  in this article. 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), or fuel pump relay output circuit (Orange/Dark Blue 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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