Mass Air Flow (MAF) Sensor (G70), Checking
MASS AIR FLOW (MAF) SENSOR (G70), CHECKINGFor installation location -> Repair Group 24
Requirement:
^ fuse 27 OK
(in the fuse/relay panel)
VOLTAGE SUPPLY, CHECKING
- disconnect Mass Air Flow sensor harness connector.
- switch Fluke 83 multimeter to 20 Volt range.
- connect multimeter between terminals 2 and 3, using jumper wires from VW 1594 adapter kit.
- switch ON ignition.
^ must be between approx. 12 and 14 Volts.
If specified value NOT attained
- check that fuse 27 is OK.
^ in the fuse relay/panel
- check wiring between terminal 3 and circuit breaker I for continuity using wiring diagram.
^ must be max. 0.5 Ohms
- check wiring between terminal 2 and engine ground for continuity.
^ must be max. 0.5 Ohms
WIRING BETWEEN ENGINE CONTROL MODULE (ECM) AND MASS AIR FLOW (MAF) SENSOR, CHECKING
- disconnect ECM from ECM harness connector.
- connect VAG 1598 Test Box to ECM harness connector using adapter cable VAG 1598-11, -> Repair Group 01 (Fuel and Ignition) for additional information.
^ the ECM is left disconnected
- check signal wire for continuity between terminal 1 of MAF sensor and terminal 42 of Test Box.
^ must be max. 1 Ohm
If the specified values are NOT obtained
- eliminate open circuit or short between MAP sensor harness connector and connector A for the ECM.
Note:
If terminals within the harness connector are replaced, ONLY use gold-plated terminals.
MASS AIR FLOW (MAF) SENSOR FUNCTION, CHECKING
- pry protective rubber boot away from MAF sensor harness to expose harness connector terminals
^ harness connector remains connected to MAF sensor
- switch Fluke 83 multimeter to 2 Volt range.
- connect multimeter between terminals 1 and 2 using jumper wires from VW 1594 adapter kit.
- switch ON ignition.
^ must be approx. 0.3 to 1.1 Volts
- start engine and let idle.
- switch OFF all electrical consumers.
^ radiator cooling fan must NOT be running
- continuously vary RPM (by hand) between idle speed and 4000 RPM.
^ depending on RPM, voltage must change between max. 1.5 to 3.4 Volts
If NO
- replace MAF sensor.
SPEED SIGNAL, CHECKING
- disconnect ECM from ECM harness connector
- connect VAG 1598 Test Box to ECM harness connector B using adapter cable VAG 1598-11 -> Repair Group 01 (Fuel and Ignition) for additional information.
- connect VAG 1527B LED tester between terminals 29 (signal) and 40 (plus) of Test Box.
- switch ON ignition.
^ LED tester must light up at about half strength
- lift front end of vehicle to allow wheels to be turned by hand.
- turn left front wheel.
^ LED tester must become brighter (flashing)
If NO
- using wiring diagram check wiring for continuity between terminal 29 of Test Box and instrument cluster.
If NO
- eliminate open circuit between terminal 9 of harness connector B and instrument cluster.
If wiring OK
- continue troubleshooting using wiring diagram and component location diagrams.
If LED tester lights up and flashes
- switch OFF ignition.
- connect VAG 1598-11 adapter cable connector B to ECM connector B.
- connect LED tester to terminal 29 (signal) and 40 (plus) of Test Box.
- switch ON ignition.
^ LED tester must light up at half strength
- turn left front wheel slowly by hand.
^ LED tester must become brighter (flash)
If NO and if there were no stored Diagnostic Trouble Codes AND the ECM harness connector B was disconnected while performing the electrical checks
- replace (J 192) ECM.