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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN PASSENGER EXTENDED, 5.0 MREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS SELF-DIAGNOSTICS - 5.0L & 5.7LDIAGNOSTIC TESTSDTC P0507: IDLE CONTROL SYSTEM - HIGH RPMDIAGNOSTIC PROCEDURES
2001 Chevrolet Chevy Express G2500, Van Passenger Extended, 5.0 M

Diagnostic Procedures

2001 Chevrolet Chevy Express G2500, Van Passenger Extended, 5.0 MSECTION Diagnostic Procedures
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
    2. NOTE: Ensure engine speed stabilizes with each commanded RPM change to determine if engine speed stays within 50 RPM of commanded RPM.
  2. Set parking brake and block drive wheels. Install a scan tool. Start engine. Turn all accessories off. Using scan tool RPM control function, slowly increment engine speed to 1800 RPM, then to 600 RPM, then to 1800 RPM. Exit RPM control function. If engine speed stabilizes within 100 RPM of commanded RPM during test, go to next step. If engine speed does not stabilize within 100 RPM go commanded RPM during test, go to step  4.
  3. Observe FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME/FAILURE RECORDS data as possible. If DTC failed this ignition cycle, go to next step. If DTC did not fail this ignition cycle, see DIAGNOSTIC AIDS .
  4. Turn ignition off. Disconnect IAC valve. See COMPONENT LOCATIONS . Connect an IAC Motor Driver (J 37027-A) to IAC valve. Start engine. Using IAC motor driver, command IAC valve in until about 600 RPM is reached. Using IAC motor driver, command IAC valve out until about 1800 RPM is reached. Return engine speed to desired idle as indicated on scan tool data list. If engine speed steadily decreased to about 600 RPM and steadily increased to about 1800 RPM when IAC valve was commanded in and out, go to next step. If engine speed does not steadily decreased to about 600 RPM and steadily increased to about 1800 RPM when IAC valve was commanded in and out, go to step  10.
  5. Using a test light connected to ground, probe one of the IAC valve circuits at IAC valve harness connector using Connector Test Adaptor Kit (J 35616-A). Start engine. Using IAC motor driver, command low RPM while observing scan tool until IAC counts start to increment. Using IAC motor driver, command high RPM while observing scan tool until IAC counts start to increment. While IAC counts are incrementing observe test light. Return engine idle speed to desired idle as indicated on scan tool data list. Repeat procedure for other three IAC valve circuits. If test light remains on (never flashing) while IAC counts were incrementing at any IAC valve circuits during test, go to step  9. If test light does not remain on (never flashing) while IAC counts were incrementing at any IAC valve circuits during test, go to next step.
  6. If test light remains off (never flashing) while IAC counts were incrementing at any of the IAC valve circuits during test, go to step  8. If test light does not remain off (never flashing) while IAC counts were incrementing at any of the IAC valve circuits during test, go to next step.
  7. Connect a test light between IAC valve connector terminals "C" (Light Blue/Black wire) and "D" (Light Blue/White wire) using connector test adaptor kit. See Figure. Using IAC motor driver, command low RPM while observing scan tool until IAC counts start to increment. Using IAC motor driver, command high RPM while observing scan tool until IAC counts start to increment. While IAC counts are incrementing, observe test light. Return engine idle speed to desired idle as indicated on scan tool data list. Repeat procedure with test light connected between IAC connector terminals "A" (Light Green/Black wire) and "B" (Light Green/White wire). Return engine speed to desired idle as indicated on scan tool data list. If test light stayed illuminated (never flashing) while IAC counts where incrementing during test, see DIAGNOSTIC AIDS . If test light did not stay illuminated (never flashing) while IAC counts where incrementing during test, go to step  14.
  8. Turn ignition off. Disconnect PCM harness connectors. Using a DVOM, check for open or short to ground on IAC valve circuit where test light remained off. If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to step  11.
  9. Turn ignition on. Using a DVOM, check for short to voltage on IAC valve circuit where test light remained illuminated. If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to step  11.
  10. Inspect for the following conditions:
    • Throttle body damage and tampering.
    • Throttle lever screw tampering.
    • Vacuum leaks.
    • A faulty or incorrectly installed PCV valve and hose.
    • Throttle shaft binding.
    • Throttle linkage or cruise control linkage binding. Remove IAC valve. Inspect for debris in IAC passage, excessive deposits on throttle plate, excessive deposits in throttle bore, and excessive deposits on IAC valve pintle.

    If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to step  12.

  11. Check PCM connectors for poor connections. If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to step  14.
  12. Check IAC valve connector for poor connections. If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to next step.
  13. Replace IAC valve. After repairs, go to step  15.
  14. Replace PCM. Program PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  15. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria. If DTC runs and passes, go to next step. If DTC does not run and pass, go to step  2.
  16. Using scan tool, observe stored information. If scan tool displays any DTCs that have not been diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not display any DTCs, system is okay.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.