A8 Quattro Sedan V8-4.2L (ABZ) (1998)
Main Relay (Computer/Fuel System): Testing and Inspection
Motronic ECM Power Supply Relay, Checking
The Motronic ECM power supply relay -J271- is located in the electronics box (E-box) in the plenum.
See Electrical Wiring Diagrams, Troubleshooting and Component Locations.
The relay supplies power to the following components:
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Fuel injectors
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Motronic Engine Control Module (ECM) -J220-
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EVAP canister purge regulator valve -N80-
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Intake manifold change-over valve -N156-
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Air control valve for fuel injectors -N212-
Checking
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Remove Motronic ECM power supply relay -J271- from relay position 1 (E-box in plenum).
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Connect VAG 1527 LED voltage tester between relay socket terminal 2 (B+, terminal 30) and engine Ground.
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Connect VAG 1527 LED voltage tester between relay socket terminal 4 (B+, terminal 30) and engine Ground.
LED must light up both times.
If LED does not light;
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Check wiring for open circuits.
See Electrical Wiring Diagrams, Troubleshooting and Component Locations.
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Connect VAG 1527 LED voltage tester between relay socket terminals 2 (B+, terminal 30) and 6 (Ground for ECM).
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Switch ignition on.
LED must light up.
If LED does not light:
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Switch ignition off.
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Connect VAG 1598/19 test box to ECM harness connector. See: Computers and Control Systems/Testing and Inspection