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Home >> Chevrolet >> 2001 >> Impala Police >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P0101: MAF System Performance >> Diagnostic Procedures
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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. Install scan tool. Start engine. Monitor DTC information using scan tool. 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 does not fail this ignition cycle, see DIAGNOSTIC AIDS .
  4. Allow engine to 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 0.8-4.0 volts, see MANIFOLD ABSOLUTE PRESSURE SENSOR under appropriate SYSTEM & COMPONENT TESTING article.
  5. Turn ignition off. Inspect for objects blocking air inlet screen of MAF sensor or plugged or collapsed intake air duct or dirty air filter element. Inspect for vacuum leaks in intake manifold, throttle body, EGR valve flange and pipe, MAF sensor seal, MAP sensor seal, EVAP canister purge valve seal, fuel meter body seal, crankcase ventilation system, brake booster system, and 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. Remove MAP sensor from engine vacuum source. Leave electrical harness connected. Connect a hand operated vacuum pump to MAP sensor. Turn ignition on, engine off. Using scan tool, observe or record MAP sensor kPa parameter display as you slowly apply vacuum 3 kPa at a time up to 68 kPa as indicated on pump gauge. Each 3 kPa of vacuum applied should result in a 3 kPa to 4 kPa drop in MAP sensor value on scan tool. Value should change smoothly with each 3 kPa increase in vacuum. If scan tool indicates MAP sensor value changed smoothly through entire range of test, go to next step. If scan tool indicates MAP sensor value did not change smoothly through entire range of test, see MANIFOLD ABSOLUTE PRESSURE SENSOR under appropriate SYSTEM & COMPONENT TESTING article.
  7. Apply 68 kPa 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 MANIFOLD ABSOLUTE PRESSURE SENSOR under appropriate SYSTEM & COMPONENT TESTING article.
  8. Disconnect vacuum source from MAP sensor. If scan tool indicates MAP sensor reading returned to original value observed in step  6, go to next step. If scan tool does not indicate MAP sensor reading returned to original value observed in step  6, see MANIFOLD ABSOLUTE PRESSURE SENSOR under appropriate SYSTEM & COMPONENT TESTING article.
  9. Using scan tool, observe TP sensor angle parameter between closed throttle and 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 does 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. See Figure or Figure . Turn ignition on, engine off. Measure voltage between MAF sensor connector terminal "A" (Yellow wire) and ground. See Figure. If voltage measures about 5.0 volts, go to next step. If voltage does not measure 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 measures less than 4.5 volts, go to step  15. If voltage does not measure 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 measures about zero volts, go to step  22. If voltage does not measure about 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 Black/White wire. 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 sensor and ground. After repairs, go to step  23.
  17. Repair short to ground or open in Pink wire between MAF sensor and fuse. Replace fuse if necessary. After repairs, go to step  23.
  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. 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  22.
  21. Replace MAF sensor. After repairs, go to step  23.
  22. Replace PCM. Program replacement 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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