Do these need a relay or decoder to work?

Switchback function runs without extra wiring — amber automatically triggers on brake input. Sequential timing is built into the LED module itself, no external controller needed.

Will the puddle lights drain my battery when parked?

Puddle lights draw minimal amperage and only activate with door unlock or when the interior courtesy lights trigger. No measurable impact on battery sitting overnight.

Can I install these myself, or do I need a shop?

Mirror signal replacement is straightforward if you're comfortable removing the mirror trim panel and unplugging the OEM connector. Basic hand tools and roughly 30 minutes per side. Check a service manual for your specific trim removal steps first.