Boat Trailer Turn Signals and Brake Lights Work But Not Running Lights
Question:
Does the boat have to be on trailer ball for weight to make better ground or contact? Light bulbs are good.... sounds like a ground issue...
asked by: Jay M
Expert Reply:
If the turn and brake lights on your boat trailer work but the running lights do not, then this does suggest a potential grounding issue. Turn and brake lights will generally draw less current since they do not remain on as running lights do so sometimes a marginal ground will let some lighting functions work normally while others do not.
You can also check your two connectors for any signs of discoloration or corrosion that could be interfering with signal transmission. Even slight greenish or whitish discoloration can indicate corrosion bad enough to block a signal.
Some trailers will rely on the mechanical connection between the trailer coupler and the tow vehicle hitch ball to provide some grounding between the two. If your trailer has a folding tongue then you may need to install a ground jumper wire between the lights' grounds and the main trailer ground.
You can also check that the individual lights' ground wires are solidly attached to the frame, or again in the case of an aluminum trailer, that you have a ground jumper wire from each light to the main trailer connector.
You can also test the trailer lights directly by disconnecting the trailer and applying 12V battery power to the trailer connector's pins. Please see the linked article for pictures of the connectors and usual pin assignments.
If you have a circuit tester like # PTW2993 you can test the trailer connector on the tow vehicle for proper signals with the trailer disconnected. If the running light signal is present at the vehicle, then you can be reasonable sure the issue is on the trailer side.
Products Referenced in This Question
Product Page this Question was Asked From
Adapter 7-Pole to 4-Pole and 5-Pole
- Trailer Wiring
- Wiring Adapters
- Multi-Function Adapter
- 7 Round - Blade
- Plug Only
- 4 Flat
- 5 Flat
- Hopkins
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