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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 P0234: TC Engine OVERBOOST Condition (Ca) >> 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. Install a scan tool. Start the engine. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool. Does the scan tool indicate that DTC P0108 is current? If yes, see DTC P0108: BARO SENSOR CIRCUIT - HIGH PRESSURE (CA) . If no, go to next step.
  3. Allow the engine to reach operating temperature. Turn OFF the ignition. Turn ON the ignition, with the engine OFF. Does the scan tool indicate that the difference between the boost sensor pressure and the BARO sensor pressure is more than 10 kPa? If yes, go to step  7. If no, go to next step.
  4. Turn OFF the ignition. Inspect for a ruptured or disconnected pressure hose from the charged air tube to the wastegate actuator. Did you find and correct the condition? If yes, go to step  14. If no, go to next step.
  5. Remove the hose from the wastegate actuator tube. Connect a hand vacuum pump to the actuator tube. Apply 15 in. Hg of vacuum. Does the vacuum hold? If yes, go to next step. If no, go to step  11.
    6. CAUTION: Wear safety glasses when using compressed air in order to prevent eye injury.
  6. Apply compressed air, not exceeding 45 psi, to the actuator tube. The wastegate should begin to open near 30 psi and fully open at 45 psi. The actuator rod stroke should measure near 4 mm. Does the wastegate move to the open position? If yes, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM. If no, go to step  11.
  7. Disconnect the boost sensor electrical connector. Connect a test lamp to battery voltage. Probe the low reference circuit of the boost sensor with the test lamp. Does the test lamp illuminate? If yes, go to step  9. If no, go to next step.
  8. Test the low reference circuit of the boost sensor for high resistance or for an open. Did you find and correct the condition? If yes, go to step  14. If no, go to step  10.
  9. Inspect for poor connections at the boost sensor. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  10. Inspect for poor connections at the ECM. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  11. Replace the turbocharger. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  14.
  12. Replace the boost sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  14.
  13. Replace the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram ECM. See ENGINE CONTROL MODULE  under PROGRAMMING. 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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