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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 141 (Engine Controls Self-Diagnostics - 5.7L - Bi-Fuel) >> Diagnostic Tests >> DTC P0102: MAF Sensor Circuit - Low Frequency >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Start and idle the engine. Using the scan tool, establish communication with the PCM. Observe the MAF sensor data parameter. Does the MAF sensor data parameter indicate airflow less than 2.5 gms/sec? If yes, go to step  5 . If no, go to next step.
  3. Using the scan tool, establish communication with the Alternative Fuels ECM. Observe the MAF sensor data parameter. Does the MAF sensor data parameter indicate airflow less than 2.5 gms/sec? If yes, go to step  8 . If no, go to next step.
  4. The fault is not present. Are any DTCs stored that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, problem is intermittent. See INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  5. Turn OFF the engine, with the ignition ON. Disconnect the MAF sensor connector. Connect a Digital Multimeter (DMM) between the MAF signal circuit terminal and ground. Is the voltage near 5 V? If yes, go to step  9 . If no, go to next step.
  6. Inspect the MAF sensor signal circuit for an open or high resistance between the sensor connector and the PCM. Inspect the MAF sensor signal circuit for a short to voltage if the circuit voltage was more than 5.2 volts. Inspect for proper terminal contact at both the PCM connector and the MAP sensor connector. Repair the wiring or terminal contact as necessary. Was a wiring or terminal repair necessary? If yes, go to step  17 . If no, go to next step.
  7. Inspect the MAF sensor signal circuit for a short to engine ground or to the sensor ground circuit. Disconnect the Alternative Fuels ECM connector containing the MAF sensor signal circuit in order to determine if the ECM is the cause of the short. Repair wiring as necessary. Was a repair or replacement necessary? If yes, go to step  17 . If no, go to step  15 .
  8. Inspect the MAF sensor signal circuit for an open or high resistance between the circuit splice and the Alternative Fuels ECM connector. Inspect for proper terminal contact at the Alternative Fuels ECM connector. Repair wiring or terminal contact as necessary. Was a wiring or terminal repair necessary? If yes, go to step  17 . If no, go to step  16 .
  9. Connect a test lamp between the ignition feed circuit terminal and the ground circuit terminal of the MAF sensor connector. Does the test lamp illuminate? If yes, go to step  13 . If no, go to next step.
  10. Connect the Unpowered Test Lamp (J 34142-B) between the ignition feed circuit terminal of the MAF sensor connector and a known-good ground. Does the test lamp illuminate? If yes, go to step  12 . If no, go to next step.
  11. Repair the cause of no MAF sensor voltage. Possible causes include the following:
    • An open ignition fuse.
    • An open or shorted to ground ignition feed circuit.
    • A shorted to ground component that shares the MAF sensor ignition feed circuit.

    Repair the wiring or replace any components as necessary. After repairs, go to step  17 .

  12. Repair the open MAF sensor ground circuit. After repairs, go to step  17 .
  13. Inspect the MAF sensor connector for proper terminal contact. Repair the terminal contact as necessary. Was a connector terminal repair made? If yes, go to step  17 . If no, go to next step.
  14. Replace the MAF Sensor. See MASS AIR FLOW SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - CHEVY EXPRESS & SAVANA - GASOLINE. After repairs, go to step  17 .
    15. NOTE: The following Control Module replacement procedures must all be completed before attempting to operate the vehicle.
  15. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CHEVY EXPRESS & SAVANA - GASOLINE. Program (flash) PCM with correct vehicle software and calibration. See POWERTRAIN CONTROL MODULE REPROGRAMMING  under PROGRAMMING. To perform CKP variation learn procedure, a switchover to gasoline operation is necessary. Remove CNG fuse (20-amp) located in underhood fuse block to perform switchover. Perform CKP system variation learn procedure. See CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE  under PROGRAMMING. After performing repairs and procedures, go to step  17 .
  16. Replace AF ECM. See ALTERNATE FUEL ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CHEVY EXPRESS & SAVANA - BI-FUEL. Program (flash) AF ECM with correct vehicle software and calibration. See ALTERNATE FUEL ENGINE CONTROL MODULE  under PROGRAMMING. After performing repairs and procedures, go to next step.
  17. Using a scan tool, clear the DTC information from BOTH control modules. Operate the vehicle under the Conditions For Running DTC. Using the scan tool parameter DTC STATUS, ensure that this DTC runs. Did this DTC run and pass? If yes, system is okay. If no, go to step  2 .
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