He wanted to control only the LEDs, but I also connected the brake lights to the 2CH to test.
If the servo arm is short, the controller may fire at the same time as it moves to the brake state.
It would be nice to connect the control module to the 12V LED.
For my board I went a step further and used an attiny85 microcontroller to translate from an RC channel to a LED driver, that way I could have running lights and tail lights using the same LED, just different PWM levels.
I also used a spare channel for high beams and low beams on a headlight.