How to Test Homemade 4-Flat to European 7 Pin Trailer Wiring Adapter

Question:

Vehicle: 2013 Ford Flex Limited without factory tow package Installed the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118472 I built an adapter using a 4 pole plug wired to a TowReady Tail light 2 wire to 3 wire converter #118158, then to a European 7 pin socket. Can I test the harness without a trailer? When should a powered tail light converter be used? Thank you.

asked by: Chris

Helpful Expert Reply:

You can test your home-brew wiring adapter without a trailer by using a circuit tester like # PTW2993 while a helper activates the various lighting functions on the vehicle. Please see the linked video.
Have your helper activate a light function on the car, say the right turn signal, while you test the output end of your harness. Ground the tester and apply the probe to the output pin. A brake signal should be a steady-on signal; a turn signal should be on-and-off; and a running light signal should be steady-on as well.

A powered taillight converter is required when a trailer's lighting will demand more power than the vehicle's wiring can safely deliver. An example of when this could occur is when a vehicle that has efficient LED lights (and also lighter gauge wiring as a result) is connected to a trailer whose lights are the standard incandescent type that require more power. A powered converted protects the vehicle's delicate internal wiring from excessive power draw that could damage it. Its easier and cheaper to replace a converter than to repair damaged wiring.

expert reply by: Adam R