Trailer Clearance Lights Show Power but Some Will Not Light Up

Updated 10/28/2013 | Published 10/25/2013

Products Featured in This Question

Optronics Trailer Tail Light - Stop, Turn, Tail - Incandescent - Round - Red Lens

(2581)

$18.11

Digital Multimeter with 42" Long Test Leads - LED Display

(3)

$21.20

Question:

tail lights work brake,turn signal,and brakelights all work. clearance lights some work some dont have conudty on all the wires whats wrong and the bulbs are all good.

asked by: Don S

Expert Reply:

It is possible that the clearance lights are not working if you have a lot of clearance lights. This can overload the trailer wiring on the vehicle side and cause some of the lights not to work. You can check the amperage draw per clearance light by testing one at a time using a multimeter such as # PT89ZR. Switching everything over to LEDs will be much better because they draw only a fraction of the power compared to incandescents.

Another possibility is a poor ground connection. All of the trailer lights will need to be grounded to clean and corrosion free bare metal surfaces. If the trailer has an aluminum frame, tilt bed, or folding tongue then adding jumper grounds from the lights to the main trailer connector ground can help.

Also make sure the main trailer connector ground is attached to a clean and corrosion free bare metal surface. The trailer and vehicle side connectors will need to be clean of dirt and corrosion inside where the wires attach and outside on the pins. A poor ground connection means the circuit cannot be completed and the lights will not work.

Make sure that the lights that are not working having wiring that is in good shape and repair as needed.

expert reply by: Michael H