EuroVan (2.5L)

WARNING: This page is about a different car, the 1993 Volkswagen EuroVan. However, it is still accessible from the selected car via links, so may be relevant.

Check Idle Air Control (IAC) valve using OUTPUT DIAGNOSTIC TEST MODE. See the TESTS W/CODES article. Turn ignition on. IAC valve must vibrate or hum. If IAC valve does not vibrate or hum, turn ignition off and disconnect IAC valve.
Connect Digital Volt-Ohmmeter (DVOM) to IAC valve using test leads from Adapter Kit (VW 1594). IAC valve resistance should be 2-10 ohms. If resistance is incorrect, replace IAC valve.
NOTE: IAC valve control current amperage may vary between 400-1000 milliamps depending on engine load (A/C on, power steering at full lock, incorrect ignition timing).
If IAC valve is working properly, ensure engine coolant temperature is at least 176°F (80°C). Ensure idle speed is correctly set and no air leaks exist in air intake system.
With IAC valve disconnected, install Test Harness (VAG 1315A/2) between IAC valve and wiring harness connector. See Fig 1 . Using test leads from adapter kit, connect DVOM to test harness.
Start engine and allow it to idle. With engine at 775-825 RPM, IAC valve control current must be 500-600 milliamps. With throttle closed, disconnect Blue Engine Coolant Temperature (ECT) sensor.
With ECT sensor disconnected, IAC valve control current must remain at 500-600 milliamps. If IAC valve control current is not as specified, repair circuit or replace ECM as necessary.

NOTE: If engine stalls, reconnect ECT before re-starting engine. This will prevent ECM from entering "limp home" mode, making IAC control current measurements inaccurate.

Fig 1: Testing Idle Air Control Valve (EuroVan)

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