Audi 80 Quiz
Body Electrical System

Contact X Relief Relay

In this manual: Body Electrical System
Technical Description — 39Engines — 41Exhaust System — 13Cooling System — 28Fuel tank and fuel pump — 12Air Filter and Intake Ducts — 13Mono-Motronic Injection System — 18Digifant Injection System — 19KE-III-Jetronic Injection System — 35MPI and MPFI Injection Systems — 32Clutch — 11Transmission and Driveline — 21Suspension and Steering — 33Brake System — 41Anti-lock brake system — 8Wheels and Tires — 13Body Electrical System — 35Ignition System — 24Lighting — 14Signaling Devices — 7Instruments and Auxiliary Equipment — 54Heating and Ventilation — 7Body Components — 18Troubleshooting — 6Specifications — 13
~1min read

The contact X relief relay (a simple switching relay) plays an important role in the electrical system. Therefore its operating principle is described here.


Terminal X of the ignition switch receives power only when the ignition key is in the "driving" position. High-current consumers such as the windshield wipers, rear window defroster, or blower fan are connected through this terminal so that during engine cranking all of the battery's power is available to the starter motor. Of course, not all of these consumers can receive their power through the ignition switch contact, since it is too weak for that. Therefore, a relay must be connected between them and the power supply. The ignition switch contact (together with the headlight power supply) carries only the switching current to the relay.

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A quick Audi 80 quiz: every answer comes with an explanation and a link to the manual page.