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Home >> Cadillac >> 1998 >> Catera >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0110 - IAT Sensor Circuit >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  , then go to next step.
  2. Turn ignition on, with engine off. Using scan tool, monitor IAT sensor temperature. If IAT sensor temperature is greater than 282°F (139°C), go to step 6). If IAT sensor temperature is less than 282°F (139°C), go to next step.
  3. If IAT sensor temperature is less than -45°F (-43°C), go to step 8). If IAT sensor temperature is greater than -45°F (-43°C), go to next step.
  4. Turn ignition on, with engine off. Move IAT sensor and ECM wiring harness and connectors while observing scan tool display. If IAT sensor value on scan tool display changes when moving wiring harness or connectors, go to step 12). If IAT sensor value on scan tool display does not change when moving wiring harness or connectors, go to next step.
  5. Turn ignition on, with engine off. Review FREEZE FRAME data for this DTC and note parameters. Clear DTCs. Turn ignition off for 15 seconds. Start engine and operate for at least 3 minutes, as close to conditions recorded in FREEZE FRAME as possible. Check for DTCs. If DTC P0110 is set, go to next step. If DTC P0110 is not set, see DIAGNOSTIC AIDS.
  6. Disconnect IAT sensor harness connector. Observe scan tool display. If IAT sensor temperature is less than -45°F (-43°C), go to step 17). If IAT sensor temperature is greater than -45°F (-43°C), go to next step.
  7. Turn ignition off. Disconnect ECM harness connector, located in engine compartment relay center. Using DVOM, check continuity between IAT sensor signal circuit and ground. If continuity is present, go to step 13). If continuity is not present, go to step 19).
  8. Disconnect IAT sensor connector. Jumper IAT sensor harness connector terminals together. Observe scan tool display. If IAT sensor temperature is greater than 282°F (139°C), go to step 16). If IAT sensor temperature is less than 282°F (139°C), go to next step.
  9. Jumper IAT sensor signal circuit to a known good ground. Observe scan tool display. If IAT sensor temperature is greater than 282°F (139°C), go to step 11). If IAT sensor temperature is less than 282°F (139°C), go to next step.
  10. Turn ignition off. Disconnect ECM harness connector located in engine compartment relay center. Using DVOM, check continuity of sensor signal circuit between ECM and IAT sensor harness connectors. If continuity is present, go to step 18). If continuity is not present, go to step 14).
  11. Turn ignition off. Disconnect ECM harness connector located in engine compartment relay center. Using DVOM, check continuity of sensor ground circuit between ECM and IAT sensor harness connectors. If continuity is present, go to step 18). If continuity is not present, go to step 15).
  12. Repair harness or connections as necessary. After repairs, go to step 20).
  13. Repair short to ground in signal circuit. After repairs, go to step 20).
  14. Repair open or high resistance in signal circuit. After repairs, go to step 20).
  15. Repair open or high resistance in ground circuit. After repairs, go to step 20).
  16. Check for poor connections and terminal tension at IAT sensor harness connector. Repair as necessary. After repairs, go to step 20). If connections and terminals are okay, go to next step.
  17. Replace IAT sensor. After replacing sensor, go to step 20).
  18. Check for poor connections and terminal tension at ECM harness connector. Repair as necessary. After repairs, go to step 20). If connections and terminals are okay, go to next step.
  19. Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing ECM, go to next step.
  20. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate at least 3 minutes, and as close to conditions recorded in FREEZE FRAME as possible. Check for DTCs. If DTC P0110 is set, go to step 2). If DTC P0110 is not set, go to next step.
  21. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.
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