Set a button's behaviour to Effect in Daniel Newman Racing > Steering Wheels > Button Effects, then choose one of these from the Button Effect list. Each one lights that button from live game telemetry.

• Headlights. Lit while your headlights are on.
• Flasher. Lit while you are flashing your headlights at somebody.
• Headlights and Flasher. One button that covers both, for wheels where the same control does both jobs.
• Rain Light. Lit while the rear rain light is on.
• Left Indicator and Right Indicator. Lit while that indicator is running.
• Hazard Lights. Lit while the hazards are on.
• Wipers. Lit while the wipers are running.

The colour comes from that button's own colour setting, which is only editable on the Custom theme and is overridden while Universal Theme is on. If an effect is lighting up but in the wrong colour, that is the usual cause.

These effects can only show what the game reports. A sim that does not publish a wiper or rain light state cannot drive that LED, and the effect will simply never trigger in that title.

There is also a separate Headlight Flash animation for your RPM and telemetry LEDs, on the Telemetry page's Effects tab, which flashes the main bar rather than a single button.