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Home >> Cadillac >> 1998 >> Eldorado Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Engine Sensors & Switches >> Engine Controls - System/Component Tests >> Engine Oil Pressure Sensor Diagnosis
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Engine Oil Pressure Sensor Diagnosis

  1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES article.
  2. Connect scan tool to data link connector. Turn ignition switch to RUN position. Observe engine oil pressure on scan tool. If LOW is displayed, go to next step. If LOW is not displayed, go to step 6).
  3. Start engine and let idle. Observe engine oil pressure on scan tool. If OK is displayed, system is okay at this time. If OK is not displayed, go to next step.
  4. Turn ignition switch to LOCK position. Disconnect engine oil pressure sensor harness connector. Turn ignition switch to RUN position. Observe engine oil pressure on scan tool. If OK is not displayed, go to next step. If OK is displayed, go to step 15).
  5. Using scan tool, record FLUID LIFE INDEXES. Turn ignition switch to LOCK position. Wait 30 seconds. Disconnect PCM harness connector containing engine oil pressure sensor input circuit. Measure resistance in engine oil pressure input circuit (Tan/Black wire) between PCM and engine oil pressure sensor harness connectors. If resistance is not 10,000 ohms or greater, go to next step. If resistance is 10,000 ohms or greater, go to step 15).
  6. Turn ignition switch to LOCK position. Disconnect engine oil pressure sensor harness connector. Using a fused jumper wire, connect engine oil pressure sensor harness connector terminals. Observe engine oil pressure on scan tool. If LOW is not displayed, go to next step. If LOW is displayed, go to step 15).
  7. Using a fused jumper wire, ground engine oil pressure input circuit (Tan/Black wire) at engine oil pressure sensor harness connector. Observe engine oil pressure on scan tool. If LOW is not displayed, go to next step. If LOW is displayed, go to step 12).
  8. Remove jumper wire. Measure voltage at engine oil pressure input circuit (Tan/Black wire) at engine oil pressure sensor harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, go to step 10).
  9. Using scan tool, record FLUID LIFE INDEXES. Turn ignition switch to LOCK position. Wait 30 seconds. Disconnect PCM harness connector containing engine oil pressure sensor input circuit. Turn ignition switch to RUN position. Measure voltage at engine oil pressure input circuit (Tan/Black wire) at engine oil pressure sensor harness connector. If 0.5 volts or greater exists, go to step 13). If 0.5 volts or greater does not exist, go to step 17).
  10. Using scan tool, record FLUID LIFE INDEXES. Turn ignition switch to LOCK position. Wait 30 seconds. Disconnect PCM harness connector containing engine oil pressure sensor input circuit. Turn ignition switch to RUN position. Measure resistance in engine oil pressure input circuit (Tan/Black wire) between PCM and engine oil pressure sensor harness connectors. If 5 ohms or less does not exist, go to step 14). If 5 ohms or less exists, go to step 17).
  11. Repair short to ground in engine oil pressure sensor input circuit.
  12. Repair open in engine oil pressure sensor ground circuit.
  13. Repair short to voltage in engine oil pressure sensor input circuit.
  14. Repair open in engine oil pressure sensor input circuit.
  15. Check for poor connection at engine oil pressure sensor. If problem does not exist, go to next step. If problem exists, repair as necessary.
  16. Replace engine oil pressure sensor.
  17. Check for poor connection at PCM. If problem does not exist, go to next step. If problem exists, repair as necessary.
  18. Replace PCM.
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