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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-7B - Checking O2S Switching
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Test NTC-7B - Checking O2S Switching

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. Allow engine to idle. Inspect engine for vacuum leaks. Repair vacuum leaks as necessary. Perform TEST VER-2  . If no vacuum leaks exist, read O2S signal voltage using scan tool.
  2. If voltage is more than 0.1 volt, go to step 4). 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 (harness side), signal circuit (Black/Orange wire).
  3. If resistance is less than 5 ohms, repair short to ground in Black/Dark Green wire or Black/Orange wire. Perform TEST VER-2  . If resistance is more than 5 ohms, replace O2S. Perform TEST VER-2  .
  4. Turn engine off. Replace O2S. Turn ignition on. Using scan tool, reset adaptive fuel memory. Start engine. Allow engine to reach normal operating temperature.
  5. Using scan tool, read O2S state. If O2S state is switching, repair is complete. Perform TEST VER-2  . If O2S state is not switching, go to TEST NTC-16A  .
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