Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1990 Audi 100 Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Idle Stabilization Valve
- Close full throttle switch. Idle stabilizer valve should cycle (click sound) when switch is closed. If no click sound is heard, disconnect idle stabilizer valve connector.NOTE: Idle stabilizer valve terminal identifications are located on connector.
- Connect LED Tester (US 1115) between terminals No. 1 and 2 of idle stabilizer valve. LED tester should light up. If tester lights up and idle stabilizer valve does not work, replace idle stabilizer valve. If tester does not light up, connect voltmeter between connector terminal No. 2 and ground.
- Voltmeter should read 12 volts. If 12 volts are not present, repair break in wiring. If wiring is okay, replace ECU.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.