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Home >> Saturn >> 2002 >> SC2 Automatic, MP6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Testing & Engine Component Testing >> Air Induction Systems >> Boost Control System (BONNEVILLE, Grand PRIX, Park Avenue & Regal) >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing Diagnostic System Check - Engine Controls, go to next step.
    2. NOTE: This diagnostic assumes that the engine is in satisfactory mechanical condition and able to provide sufficient vacuum to operate the boost control system.
  2. Inspect the following items and repair any condition as necessary:
    • Vacuum lines for cracking, restrictions, and loose fit.
    • The bypass valve actuator for sticking, binding, or damage.
    • The bypass valve for sticking, binding, or damage.
    • The bypass valve linkage for binding or damage.
    • The boost control solenoid for damage.

    Did you find and correct the condition? If yes, go to step  16. If no, go to next step.

  3. Disconnect the boost signal hose from the bypass valve actuator. Connect a vacuum gauge to the boost signal hose. Start and idle the engine in park. Does the vacuum gauge read near 0 in. Hg? If yes, go to next step. If no, go to step  10.
  4. Connect a scan tool and command the boost control solenoid to 0 percent duty cycle. Observe the vacuum gauge. Does the vacuum gauge read more than 15 in. Hg? If yes, go to next step. If no, go to step  8.
  5. Turn OFF the ignition. Reconnect the boost signal hose to the bypass valve actuator. Disconnect the inlet vacuum signal hose from the bypass valve actuator. Connect a vacuum gauge to the inlet vacuum signal hose. Start and idle the engine in park. Does the vacuum gauge read more than 15 in. Hg? If yes, go to next step. If no, go to step  13.
  6. Turn OFF the ignition. Connect a vacuum pump to the inlet vacuum signal port on the bypass valve actuator. Slowly apply vacuum to 15 in. Hg. Does the bypass valve actuator retract? If yes, go to next step. If no, go to step  11.
  7. Reconnect the inlet vacuum signal hose to the bypass valve actuator. Disconnect the boost signal hose from the bypass valve actuator. Connect a vacuum pump to the boost signal port on the bypass valve actuator. Start and idle the engine in park. Slowly apply vacuum to 20 in. Hg. Does the bypass valve actuator extend? If yes, system is okay. If no, go to step  11.
  8. Turn OFF the ignition. Reconnect the boost signal hose to the bypass valve actuator. Disconnect the boost signal hose from the boost control solenoid. Connect a vacuum gauge to the boost signal port on the boost control solenoid. Start and idle the engine in park. Command the boost control solenoid to 0 percent duty cycle. Does the vacuum gauge read more than 15 in. Hg? If yes, go to step  15. If no, go to next step.
  9. Turn OFF the ignition. Disconnect the boost source hose from the boost control solenoid. Connect a vacuum gauge to the boost source hose. Start and idle the engine in park. Does the vacuum gauge read more than 15 in. Hg? If yes, go to next step. If no, go to step  14.
  10. Replace the boost control solenoid. After repairs, go to step  16.
  11. Inspect the bypass valve and bypass valve actuator linkage for binding, sticking or damage. Repair any condition as necessary. Did you find and correct a condition? If yes, go to step  16. If no, go to next step.
  12. Replace the bypass valve actuator. After repairs, go to step  16.
  13. Repair the inlet vacuum signal hose for a restriction or blockage. After repairs, go to step  16.
  14. Repair the boost source hose for a restriction or blockage. After repairs, go to step  16.
  15. Repair the boost signal hose for a restriction or blockage. After repairs, go to next step.
  16. Reconnect any disconnected components. Use the scan tool in order to clear any DTCs that may have set. Turn OFF the ignition for 30 seconds. Operate the vehicle within conditions to verify the repair. Did you verify the repair? If yes, go to next step. If no, go to step  2.
  17. With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article. If no, system is okay.
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