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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 370 (Engine Control System - Self-Diagnostics - 4.2L) >> Diagnostic Tests >> DTC P1514: Throttle Body Performance >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. 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. Are any other DTCs set? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off. Start engine. Operate vehicle within the Conditions For Running DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  4. Inspect for the following conditions:
    • Vacuum hoses for splits, kinks, and proper connections as shown on Vehicle Emission Control Information label. Inspect thoroughly for any type of leak or restriction.
    • Air leaks at throttle body mounting area and intake manifold sealing surfaces.

    Did you find and correct the condition? If yes, go to step  8. If no, go to next step.

  5. Allow the engine to reach operating temperature. Observe the MAP sensor voltage parameter with scan tool. Is the MAP sensor voltage 0.8-4.0 volts? If yes, go to next step. If no, see DTC P0105: MAP SENSOR CIRCUIT - INSUFFICIENT ACTIVITY .
  6. Idle engine. Observe the MAP sensor kPa parameter with scan tool. Increase the engine speed slowly and then back to idle. Does the MAP sensor kPa change smoothly and gradually as engine speed is increased and returned to idle? If yes, go to next step. If no, see DTC P0105: MAP SENSOR CIRCUIT - INSUFFICIENT ACTIVITY .
    7. WARNING: Turn ignition off before inserting fingers into the throttle bore. Unexpected movement of the throttle blade could cause personal injury.
  7. Inspect the throttle body for the following conditions while modulating the throttle through the entire range using scan tool:
    • Loose or damaged throttle blade.
    • Broken throttle shaft.
    • Drive mechanism damage.

    If any of these conditions exist, replace throttle body assembly. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. Did you find and correct the condition? If yes, go to next step. If no, see DIAGNOSTIC AIDS .

  8. Clear the DTCs with scan tool. Turn ignition off for 30 seconds. Start engine. Operate vehicle within the Conditions For Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  9. Observe the stored information, Capture Info with scan tool. Does 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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