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.
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HOMESERVICE MANUALSAUDI199590 QUATTRO SPORT V6-2.8L (AAH)REPAIR AND DIAGNOSISCRUISE CONTROLTESTING AND INSPECTIONVACUUM SYSTEM CHECK
1995 Audi 90 Quattro Sport V6-2.8L (AAH)
Vacuum System Check
1995 Audi 90 Quattro Sport V6-2.8L (AAH)SECTION Vacuum System Check
Before testing, ensure fuses for cruise control system are OK and brake lights are operational. Check wiring between control unit wiring harness and component before assuming component is faulty. If electrical measurements are required, use multimeter tool No. US 1119, or equivalent.
1. Disconnect vacuum hose from vacuum pump, then depress servo unit diaphragm.
2. Plug disconnected vacuum hose. Diaphragm must remain in depressed state, without moving.
3. If diaphragm returns, check vent valves, servo unit or vacuum hoses for leaks, then repair as needed.
4. If diaphragm remains depressed, vacuum system is satisfactory.
1. Disconnect vacuum hose from vacuum pump, then depress servo unit diaphragm.
2. Plug disconnected vacuum hose. Diaphragm must remain in depressed state, without moving.
3. If diaphragm returns, check vent valves, servo unit or vacuum hoses for leaks, then repair as needed.
4. If diaphragm remains depressed, vacuum system is satisfactory.
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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.