A8L Quattro Sedan V8-4.2L (AUX) (2001)
Specification: 25 to 35 ohm
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If reading does not match the specification, replace intake manifold change-over valve.
If the reading matches the specification, check voltage supply.
Checking voltage supply to intake manifold change-over valve
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Connect VAG1527B diode test lamp between engine Ground (GND) and socket 1 on connector using test leads from VAG1594 connector test kit.
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Operate starter briefly.
The diode test lamp should light up.
If diode test lamp does not light up:
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Check fuse for intake manifold changeover valve.
If fuse is OK:
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Check for open circuit and short circuit in wiring between fuel pump relay and socket 1 on connector via fuse for intake manifold change-over
valve.
If the voltage supply is OK, check activation.
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Re-install fuel pump relay and fuse.
Checking activation of intake manifold change-over valve
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Connect VAG1527B diode test lamp between sockets 1 (B+) and 2 on connector for intake manifold change-over valve using test leads from
VAG1594 connector test kit.
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Perform output Diagnostic Test Mode (DTM) and activate relevant intake manifold changeover valve. Refer to Scan Tool Testing/Output
Diagnostic Test Mode (DTM) (Function 03) See: Computers and Control Systems/Testing and Inspection
Indicated on display
Output Diagnostic Test Mode
->
Intake manifold change-over valve -N156
Indicated on display
Output Diagnostic Test Mode
->
Intake manifold tuning valve 2 -N261
If diode test lamp does not flash or lights up continuously, check wiring.
Check wiring
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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/Scan Tool Connecting and Initial Checks/Connecting VAG1598/31 Test Box" See: Computers and Control Systems/Testing and
Inspection