A8 Quattro Sedan V8-4.2L (ABZ) (1998)
Idle Air Control Valve: Testing and Inspection
Idle Air Control (IAC) Valve, Electrical Testing
Idle Air Control (IAC) Valve, Electrical Testing
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Check IAC valve -N71- mechanical function.
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Disconnect harness connector from valve.
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Connect multimeter US 1119 (Fluke 83 or equivalent) and check resistance across terminals on IAC valve.
Specified value: 7.0 - 11.0 ohms
NOTE: At room temperature the resistance is in the lower part of the specified range. At operating temperature the resistance is in the upper part of the
range.
If resistance is outside specified range:
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Replace IAC valve -N71-.
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Check readiness code. If DTC memory has been erased, generate new readiness code.
Refer "Monitors, Trips and/or Drive Cycle/Checking, Readiness Code", See: Computers and Control Systems/Testing and Inspection .
Refer "Monitors, Trips and/or Drive Cycle/Generating, Readiness Code" See: Computers and Control Systems/Testing and Inspection
Checking idle air control signal from ECM
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Disconnect wiring harness connector from IAC valve -N71- and connect VAG1527B LED voltage tester across connector terminals 1 and 2.
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Initiate output Diagnostic Test Mode (DTM) and check IAC valve. Refer "Scan Tool Testing", "Output Diagnostic Test Mode (DTM), (Function
03)", See: Computers and Control Systems/Testing and Inspection
LED must flash.
NOTE:
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The LED does not go completely out, but becomes brighter and dimmer.