Troubleshooting Dim Peterson Round Trailer Tail Light # 431800

Updated 06/28/2011 | Published 06/26/2011

Question:

Passenger side brake light is brighter than the drivers side. Also running light works on passenger side, not on drivers side. I just replaced the tail lights, new bulbs, clean wires connected, ground on bare metal etc etc. I ran a circuit check and found no problems. Im going nuts trying to figure this out. i crawled underneath the trailer and followed the wires, all seems to be in order, please help.

asked by: Patricia

Expert Reply:

Determining the cause of your dim lamps will be a process of elimination.

I would recommend using a multimeter like part # BTMT15 on the circuits feeding the lamps on your trailer. You should be reading close to 12-volts at each lamp. If you are not, you will need to do some troubleshooting.

Test the pins on the trailer connector on your vehicle, you should be getting close to 12-volts at each pin as its function is activated. If you see a dramatic difference in voltage between the vehicle and the trailer, you should closely examine the trailer.

Check the trailer connector on the vehicle and the trailer. Make sure the connectors are not corroded or damaged in any way. Examine the wiring on the trailer that feeds each lamp. Make sure all connections are secure.

Another possibility would be trying the trailer on a different vehicle. If the lamps are not dim when the trailer is attached to a different vehicle, you have eliminated the trailer as being the problem.

I attached an FAQ article on trailer wiring for you to check out also.

expert reply by: Jameson C