A8 Quattro Sedan V8-4.2L (AKB) (2002)
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Connect VAG1527B diode test lamp between engine Ground (GND) and socket 1 on connector.
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Operate starter.
The diode test lamp should light up.
If diode test lamp does not light up:
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Check continuity of wiring from socket 1 to fuel pump relay via fuse. Repair open circuit if necessary.
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If wiring is OK, check fuel pump relay. See: Fuel Delivery and Air Induction/Fuel Pump/Fuel Pump Relay/Testing and Inspection
If the diode test lamp lights up, check activation.
Testing activation of Evaporative Emission (EVAP) Canister Purge Regulator Valve
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Connect VAG1527B between diode test lamp sockets 1 (B+) and 2 of harness connector.
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Start output Diagnostic Test Mode (DTM) and select Evaporative Emission (EVAP) Canister Purge Regulator Valves -N80. Refer to Scan Tool
Testing/Output Diagnostic Test Mode (DTM) (Function 03) See: Computers and Control Systems/Testing and Inspection
The diode test lamp should blink.
If the diode test lamp does not blink or lights up continuously:
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Connect VAG1598/31 test box to multi-pin harness connector for engine control module. Do not connect to the engine control module itself. Refer
to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG1598/31 Test Box" See: Computers and Control
Systems/Testing and Inspection
If the diode test lamp lights up continuously:
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Check for short circuit to Ground (GND) in the following wiring connections:
2-pin connector on
VAG1598/31 test box,
wiring harness,
socket
socket