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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 87 (Engine Controls - Self-Diagnostics - 6.6L Diesel) >> Diagnostic Tests >> DTC P0181: Fuel Rail Temperature Sensor & IAT Sensor Temperature Not Within Specification >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Allow the engine to cool to ambient temperature. Turn ON the ignition. Monitor the IAT sensor with a scan tool. Does the scan tool indicate a temperature near ambient temperature 18°F (10°C)? If yes, go to next step. If no, go to step  4.
  3. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC fail this ignition cycle? If yes, go to step  6. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Disconnect the Mass Air Flow (MAF) sensor connector. Turn ON the ignition. Measure the voltage of the IAT signal circuit at the MAF sensor connector. Does the voltage measure near 5 V? If yes, go to next step. If no, go to step  8.
  5. Connect a test lamp to battery voltage. Probe the low reference circuit of the IAT. Does the test lamp illuminate? If yes, go to step  12. If no, go to step  9.
  6. Disconnect the air filter outlet duct to access the fuel temperature sensor. Disconnect the fuel temperature sensor electrical connector. Turn ON the ignition. Probe the fuel temperature sensor signal circuit with a Digital Multimeter (DMM) connected to ground. Does the voltage measure near 5 V? If yes, go to next step. If no, go to step  8.
  7. Connect a test lamp to battery voltage. Probe the low reference circuit of the fuel temperature sensor connector. Does the test lamp illuminate? If yes, go to step  13. If no, go to step  9.
  8. Turn OFF the ignition. Disconnect the Engine Control Module (ECM) connectors. Inspect the signal circuit for an open or for short to ground. Did you perform a repair? If yes, go to step  14. If no, go to step  10.
  9. Repair the open sensor low reference circuit. Did you complete the repair? If yes, go to step  14. If no, go to step  11.
  10. Inspect the ECM connector terminals for spreading or poor connections. Repair as necessary. Did you find and correct the condition? If yes, go to step  14. If no, go to next step.
  11. Replace the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram ECM. See ENGINE CONTROL MODULE  under PROGRAMMING. After repairs, go to step  14.
  12. Replace the MAF sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  14.
  13. Replace the fuel temperature sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to next step.
  14. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  15. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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