Headlight Relay Retrofit Kit Audi C4 100 / A6 C4 / 80 90 B4 81 85 4000

Relay control retrofit kit for main headlights (dipped beam & full beam)

Improve the lighting performance of your vehicle by converting to relay operation! This retrofit kit consists of pre-made and pre-wired components that route the working current for the main headlights (dipped and full beam) through separate relays instead of through the stalk switch.

The light switch will henceforth carry only the control current of approximately 150 mA to the relays — instead of the previous 10 A. This protects the switch from load, prevents contact burn and eliminates voltage losses of 1–2.5 V. Without this measure, only 9–11 V often reaches the bulbs instead of the required 12–13 V, which can reduce light output by up to 50%!

Your benefits with the relay retrofit kit:

• Protection of the light switch by relieving it from high working current

• Higher voltage at the headlights (approx. 13–13.5 V) for up to 50% more light output

• Works on vehicles with and without a lamp control unit – lamp monitoring is retained

• Simple installation between the stalk switch and fuse box, upstream of the lamp control unit

• Only one relay per light type (dipped beam and full beam) required

• Power supply runs directly via the central electronics using 4 mm² cable (red) – no additional fusing of the relays required

• Fast installation in approximately 30 minutes, even for enthusiasts with basic knowledge

This relay circuit significantly increases the effective voltage at the bulbs, preventing premature bulb wear and sustainably improving road safety.

Custom-made — no exchange or returns possible!

Retrofit now for brighter, safer light!

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