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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 26 (Engine Controls Self-Diagnostics - 5.0L & 5.7L) >> Diagnostic Tests >> DTC P0101: MAF Sensor Performance >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2001 GMC Savana, 2001 Chevrolet RV Cutaway, 2001 Chevrolet Cutaway, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
  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. Install scan tool. Start engine. Using scan tool, monitor DTC information. If scan tool displays any other DTCs, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not display any other DTCs, go to next step.
  3. Record 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 fails this ignition cycle, go to next step. If DTC did not fail this ignition cycle, see DIAGNOSTIC AIDS .
  4. Let engine idle at normal operating temperature. Using scan tool, observe MAP sensor voltage parameter. If scan tool indicates MAP sensor voltage is 0.8-4.0 volts, go to next step. If scan tool does not indicate MAP sensor voltage is 0.8-4.9 volts, see DTC P0106: MAP SYSTEM PERFORMANCE .
  5. Turn ignition off. Inspect for objects blocking MAF sensor air inlet screen or a plugged or collapsed air intake duct or dirty air filter element. MAF sensor is located at air cleaner. Inspect for vacuum leaks in the following components:
    • Intake manifold.
    • Throttle body.
    • Exhaust Gas Recirculation (EGR) valve flange and pipe.
    • MAF sensor seal.
    • MAP sensor seal.
    • Evaporative emission canister purge valve seal.
    • Fuel meter body seal.
    • Crankcase ventilation system.
    • Brake booster system.
    • Air induction system.

    If problem was found, repair as necessary. After repairs, go to step  23. If problem was not found, go to next step.

  6. Turn ignition off. Remove MAP sensor from engine vacuum source, with electrical harness connected. See COMPONENT LOCATIONS . Connect a hand operated vacuum pump to MAP sensor. Turn ignition on, engine off. Using scan tool, record MAP sensor kPa parameter display as you slowly apply vacuum one in. Hg at a time up to 20 in. Hg as indicated on pump gauge. Each one in. Hg of vacuum applied should result in a 3-4 kPa drop in MAP sensor value on scan tool. Value should change smoothly with each one in. Hg increase in vacuum. If scan tool indicates MAP sensor value changed smoothly through entire range of test, go to next step. If scan tool indicated that MAP sensor value did not change smoothly through entire range of test, see DTC P0106: MAP SYSTEM PERFORMANCE .
  7. Apply 20 in. Hg vacuum to MAP sensor. If scan tool indicates MAP sensor reading is equal to or less than 34 kPa, go to next step. If scan tool does not indicate MAP sensor reading is equal to or less than 34 kPa, see DTC P0106: MAP SYSTEM PERFORMANCE .
  8. Disconnect vacuum source from MAP sensor. If scan tool indicates MAP sensor reading returned to original value, go to next step. If scan tool did not indicate MAP sensor reading returned to original value, see DTC P0106: MAP SYSTEM PERFORMANCE .
  9. Using scan tool, observe TP sensor angle parameter from closed throttle to wide open throttle. If scan tool indicates TP sensor value changed smoothly and completely through 0-100 percent, go to next step. If scan tool did not indicate TP sensor value changed smoothly and completely through 0-100 percent, see DTC P0121: TP SENSOR PERFORMANCE .
  10. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on, engine off. Measure voltage between MAF sensor connector terminal "A" (Yellow wire) and ground. See Figure. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step  12.
  11. Connect a test light between MAF sensor connector terminals "B" (Black/White wire) and "C" (Pink wire). If test light is on, go to step  19. If test light is off, go to step  14.
  12. If voltage is less than 4.5 volts, go to step  15. If voltage is not less than 4.5 volts, go to next step.
    13. NOTE: Disconnecting PCM connectors may eliminate short to voltage if signal circuit is shorted to another PCM circuit.
  13. Turn ignition off. Disconnect PCM. Turn ignition on, engine off. Measure voltage between MAF sensor connector terminal "A" (Yellow wire) and ground. If voltage is zero volts, go to step  20. If voltage is not zero volts, go to step  18.
  14. Connect a test light between MAF sensor connector terminal "C" (Pink wire) and ground. If test light is on, go to step  16. If test light is off, go to step  17.
  15. Turn ignition off. Disconnect PCM. Check Yellow wire between PCM and MAF sensor for high resistance, open, short to ground or short to ground circuit of MAF sensor. If problem was found, repair as necessary. After repairs, go to step  23. If problem was not found, go to step  20.
  16. Repair high resistance or open in Black/White wire between MAF sensor and ground. After repairs, go to step  23.
    17. NOTE: Ignition 1 voltage circuit of MAF sensor is spliced to other components on vehicle.
  17. Check Pink wire between MAF sensor and fuse block for short to ground or open. If problem was found, repair as necessary. After repairs, go to step  23. If problem was not found, go to step  21.
  18. Repair short to voltage in Yellow wire between MAF sensor and PCM. After repairs, go to step  23.
  19. Check MAF sensor connector for poor connections. If problem was found, repair as necessary. After repairs, go to step  23. If problem was not found, go to step  21.
  20. Check PCM connectors for poor connections. If problem was found, repair as necessary. After repairs, go to step  23. If problem was not found, go to step  22.
  21. Replace MAF sensor. After repairs, go to step  23.
  22. Replace PCM. Program PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  23. 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.
  24. 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.
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