Turn Signals on Trailer are Dim and Not Work with Running Lights On

Question:

I have power to the light. The socket tests out. The directional light works dimly but goes out when the lights are turned on. Ive checked the ground and the wiring from the connector all the way back and everything seems to be fine.

asked by: John

Expert Reply:

There are a couple of possible reasons why the directional lights on your trailer are dim and do not work at all when the running lights are turned on.

The most common cause for this type of issue is a weak ground. A weak ground connection will usually allow enough current through for some lights to pass, but not enough for all of them. Considering that the running lights will remain continuously on when activated, unlike the brake or turn signals, they will require more power and there is simply not enough there to also activate the turn signals on your trailer. .

I recommend checking again to make sure all of your grounds are made to clean, bare metal surfaces that are free of dirt or corrosion. You should also ensure that each of the individual light grounds are secure. Some lights will use their mounting studs to make the ground connections and others will use a separate wire. Regardless of the type of lights you have, make sure that the connection is solid.

Another possible cause is that the total current demand from your trailer lights is simply more than can be handled by your wiring harness. I recommend checking the current rating on the harness to make sure that all of the trailer lights do not exceed its power rating. Replacing your trailer lights with LED versions will help.

If you are not able to resolve the issue, please let me know and I will be happy to look into this further. I have also attached a troubleshooting article that you might find helpful.

expert reply by: Chris R