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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 P0108: BARO Sensor Circuit - High Pressure (Fed) >> 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. Turn ON the ignition, with the engine OFF. Observe the BARO sensor pressure with a scan tool. Does the scan tool indicate that the pressure is more than 110 kPa? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observed. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Monitor the Diagnostic Trouble Code (DTC) Information with a scan tool. Does the scan tool indicate that DTC P1639 is current? If yes, go to step  7. If no, go to next step.
  5. Turn OFF the ignition. Disconnect the electrical connector of the BARO sensor. Turn ON the ignition, with the engine OFF. Does the scan tool indicate that the BARO sensor pressure is less than 44 kPa? If yes, go to next step. If no, go to step  9.
  6. Connect a test lamp to battery positive voltage. Probe the low reference circuit of the BARO sensor with the test lamp. Does the test lamp illuminate brightly? If yes, go to step  13. If no, go to step  12.
  7. Turn OFF the ignition. Disconnect the electrical connector of the BARO sensor. Turn ON the ignition, with the engine OFF. Does the scan tool indicate that the BARO sensor pressure is less than 44 kPa? If yes, go to next step. If no, go to step  10.
  8. Disconnect the electrical connector of the boost sensor. Does the scan tool indicate that the boost sensor pressure is less than 50 kPa? If yes, see DTC P1639: 5-VOLT REFERENCE 2 CIRCUIT . If no, go to step  11.
  9. Test the signal circuit of the BARO sensor for a short to 5 volts. Did you find and correct the condition? If yes, go to step  17. If no, go to step  16.
  10. Test the signal circuit of the BARO sensor for a short to battery voltage. Did you find and correct the condition? If yes, go to step  17. If no, go to step  16.
  11. Test the signal circuit of the Boost sensor for a short to battery voltage. Did you find and correct the condition? If yes, go to step  17. If no, go to step  16.
  12. Test the low reference circuit of the BARO sensor for high resistance or an open. Did you find and correct the condition? If yes, go to step  17. If no, go to step  14.
  13. Inspect for poor connections at the BARO sensor. Did you find and correct the condition? If yes, go to step  17. If no, go to step  15.
  14. Inspect for poor connections at the ECM. Did you find and correct the condition? If yes, go to step  17. If no, go to step  16.
  15. Replace the BARO sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  17.
  16. Replace the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram ECM. See ENGINE CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  17. 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.
  18. 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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