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Audi ur-quattro MB engine Idle Stabilisation tests
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|16| |13| |10| | 7| | 4| | 1|
|17| |14| |11| | 8| | 5| | 2|
|18| |15| |12| | 9| | 6| | 3|
(5 is chassis ground.)
Tests with a DC voltmeter:
- 14 + 5 - ignition on - Power Battery Voltage.
- 14 + 1 - ignition on - Code input B Battery Voltage.
- 8 + 1 - ignition on, throttle closed, idle switch closed - Battery Voltage
Tests with a diode test lamp:
- 17 + 5 - engine running - RPM from ECU - Diode must flash.
- 7 + 5 - ignition on - road speed sensor - left front wheel turned by hand - Diode must flash.
Tests with an ohmmeter:
- 13 + 5 - thermoswitch 800 to 1000 ohms at 20°C, 70 to 150 ohms at 80°C
- 11 + 4 - ISV attached - ISV resistance 3 to 8 ohms
Tests for cars with air conditioning:
- 6 + 5 - ignition on - E87 air conditioning on - Battery Voltage.
- 2 + 5 - ignition on - N25 air conditioning on - Battery Voltage.
Notes:
- If the ISV circuit is broken (e.g., plug removed and replaced with engine running) the ISV controller will not operate the device until the ignition has been cycled off and on.
- Ideal ISV current is 430ma, adjusted via the fuel mixture and throttle bypass. A value of exactly 470ma is an error signal from the controller.
- The idle stabilisation valve does NOT like 12V as a test voltage - it lets the smoke out. A 9V PP3 battery is ideal for testing ISVs because of its lower voltage and higher internal resistance.
- Never attempt to clean an idle stabilisation valve with an implement. At most the valve end can be immersed in a fuel solvent such as carburettor cleaner and operated with a 9v battery.
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