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.
1988 Audi 5000 CS, AutomaticFACTORY OEM SERVICE PROCEDURE
Fuel Pump Relay Control
- With ignition off. Remove fuel pump relay from relay panel. Connect multimeter between terminals No. 48 and No. 50 of relay socket. See Fig 1 .
- Multimeter should read 12 volts. Connect multimeter between terminals No. 46 and No. 50 of relay socket. Turn ignition on. Multimeter should read 12 volts.
- If multimeter does not read as specified, repair break in wiring Connect multimeter between terminals No. 46 and No. 47 of relay socket. Momentarily engage starter. Multimeter should read 7 volts.
- If multimeter does not read 7 volts, partially remove ICU and disconnect harness connector. Using a multimeter, check continuity between ICU and relay socket.
- Connect terminal No. 3 of ICU connector to terminal No. 49 of relay socket. Connect terminal No. 14 of ICU and terminal No. 47 of relay socket. Multimeter should read .2 ohm.
- If reading is not as specified, repair break in wiring. If reading is as specified, replace knock sensor.
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.