I've been a trailer technician for over 24 years. I've been asked a few times to build a small test box for customers over the years when they see what I have built to use in the shop.
Trailer light test box that runs off a Milwaukee M18 battery.
M18 battery not included.
Will test all functions of the trailer lights.
Just plug in the 7RV plug on the end of the box, add an M18 battery installed on the other side, turn on the main power, under the lid by the handle and start testing!
Box is built with the newer style plug in 7RV plug, so it's easier to change out.
Flashers on the box indicate right and left turn.
Right and left are the same wiring/bulb as brake lights.
Test tail.
Test electric brakes.
Test hot wire, if the trailer has interior lights or exterior lights.
Test backup lights or backup solenoid.
Has fuses on each function and a fuse on main power.
B - Electric Brakes
H - Hot Wire
B/U - Backup
L - Left Turn / Brake Lights
T - Tail / Marker Lights
R - Right Turn / Brake Lights
Switches have led lights on them so it's easy to see what is turned on.
