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Mass Airflow Sensor: Notes

WARNING: DO NOT touch the hot wire element in the MAF sensor.
NOTE: All voltage and continuity tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated differently in testing procedures. For help with diagnostic testing. See WIRING DIAGRAMS .

Location of Mass Airflow (MAF) sensor and harness connection. See COMPONENT LOCATIONS .

  1. Disconnect MAF sensor harness connector. Connect (US 1115) LED tester between harness connector terminal No. 1 and remote positive cable connection. LED tester must light up. See Figure.
  2. If LED tester did not light up, locate and repair open in circuit. See WIRING DIAGRAMS .
  3. Connect LED tester between MAF sensor terminal No. 5 and engine ground. Switch ignition ON. LED tester must light up.
  4. If NO, connect (VAG 1598) test box to Electronic Control Module (ECM) harness connector using (VAG 1598/5) adapter cable. See CONNECTING VAG 1598 TEST BOX .
  5. Connect LED tester between terminal No. 19 (ground), and terminal No. 37 of test box.
  6. Switch ignition ON. LED tester must light up. If LED tester did light up, locate and repair open in circuit between terminal No. 37 of ECM harness connector, and terminal No. 5 of MAF sensor connector. See Figure and Figure . If LED tester did not light up, replace ECM. After replacement of ECM, see ECM IDENTIFICATION and ECM CODING under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS article.
  7. Connect LED tester between terminal No. 5 of MAF sensor connector and engine ground. See Figure.
  8. Switch ignition ON. Operate starter for a few seconds. LED tester must light up when ignition is switched ON and during starter operation. If LED tester goes out during starter operation: Verify that injector valve circuit breaker S72 is Okay. See Figure and FUEL CONTROL  .
  9. Check continuity between terminal No. 5 of sensor connector, and injector valve circuit breaker S72. Resistance must be 0.5 ohm maximum. See WIRING DIAGRAMS .
  10. Check continuity between: injector valve circuit breaker S72 and terminal No. 31 of fuel pump relay -J17-, relay location 6. Resistance must be 0.5 ohm maximum. See Figure. See WIRING DIAGRAMS .
  11. Check fuel pump relay and if necessary, check control signal to fuel pump relay. See FUEL PUMP RELAY  and FUEL PUMP RELAY CONTROL SIGNAL .
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