S8 Quattro Sedan V8-4.2L (AYS) (2002)
Variable Induction Control Valve: Testing and Inspection
Intake Manifold Change-Over Valve - N156-, Checking
Intake Manifold Change-Over Valve -N156-, Checking
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Let vehicle run at idle for 2 to 3 minutes (vacuum build-up).
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Switch off engine.
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Switch ignition on.
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Perform Output Diagnostic Test Mode (DTM) and activate intake manifold change-over valves. 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 (DTM)
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Intake manifold change-over valve -N156
Solenoid valve must click (by touch or audibly). Output Diagnostic Test Mode (DTM) will be aborted after one minute.
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Solenoid valve does not click.
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Switch ignition off.
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Disconnect connector from solenoid valve for intake manifold change-over.
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Perform a resistance measurement between the solenoid valve terminals using VAG1526.
Specification: 25 to 35 Ohm
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If the specified value is not reached, replace intake manifold change-over valve.
If the specified value is obtained, check voltage supply.
Checking voltage supply of intake manifold change-over valve