S4 Quattro Sedan V6-2.7L Turbo (APB) (2000)
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Connect hand-held multimeter (voltage measurement range) between engine Ground (GND) and socket 2 of connector.
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Operate starter briefly.
Specification: approx. battery voltage
NOTE: The mass air flow sensor receives its voltage supply via the fuel pump relay.
If the reading does not match the battery voltage:
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Check for open circuit or short to Ground (GND) in wiring between fuel pump relay and socket 2 on connector via fuse. Repair if necessary.
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Connect hand-held multimeter (voltage measurement range) between sockets 2 and 3 of connector.
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Operate starter briefly.
Specification: approx. battery voltage
NOTE: Socket 3 on the connector is the Ground (GND) connection from the engine control module.
If the specification is not attained:
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Check wiring.
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Connect hand-held multimeter (voltage measurement range) between sockets 3 and 4 of connector.
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Switch ignition on.
Specification: approx. 5 V
If the specification is not attained:
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Check wiring.
Checking wiring for mass air flow sensor
NOTE: The wiring test includes also testing the signal wire.
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Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to the engine control module itself. Refer to "Scan
Tool Testing/Wiring And Component Check With VAG1598/31 Test Box", See: Testing and Inspection
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Check for open circuit and short to B+ or Ground (GND) in the following wiring connections: