Pre-trip ???

Look for a reflection off of something; maybe another truck parked behind you or a wall, anything.

 

I use a screwdriver that I wedge the pedal with. Thats also how I check the slack adjusters

 

If someone is behind you, jab the brakes. If they run into you, chances are your brake lights don't work

 

An officer will tell you. They are nice and will go out of their way to tell you this useful information.

You can check them at night as you back to a dock or in a parking lot or like scythe said you can wedge something against the pedal. I used my logbook/leather cover worked good.

 

That's one thing the old Ford/Sterling trucks had an advantage on. The brake light circuit was interconnected with the hazard flashers so in those trucks, turning on the hazard flashers also flashed the brake lights on the trailer.

 

i never wanted to run that fast to see if they were on,good idea to check them that is a major violation if they are both out. be safe

 

Use the trailer valve.