Pre-trip ???

Pulling your trolly brake will turn on your brake lights. Thats how I check mine.

Hurst

 

Why do you need to see your brake lights? You should know if you're slowing down

 

I take my plastic clip board, it has a carry handle. The weight of the note book inside it, i put the valve through the handle of the case and the weight holds it down. I also release the trailer brake when I do this, so the service brakes apply on the trailer brake and I can listen for air leaks and see that the tractor and trailer brake lights work.

FYI, just having the brake lights flash(with a early Ford/Sterling with hazards on) as one driver mentioned is not the most accurate way to check them. If your brake light switch, or brake light fuse is blown, OR you have an electrical problem on the trailer or the pig tail, they may light up on the "hazard" circuit and flash, but will not light up when your foot is applied to the brake. YES, the bulb may work in hazard mode, but does it work when the foot brake is applied?