Two types of tail light designs are found on vehicles: an independent bulb system and a common bulb system. If the brake light and turn signal operate from the same bulb, the tail light design is common. If the brake and turn work from separate bulbs, the design is independent. The industry standard found on trailers is a common bulb system. Vehicles will vary depending on the make and model. Any vehicle that has an independent bulb system must have a converter to“convert” the independent system to a common which is required on a trailer. A converter enables vehicles with independent brake lights and turn signals to provide proper lighting to the trailer.
Electronics on many newer vehicles are not equipped to handle the extra amp load that trailer lights require. A power converter provides power directly from the battery bypassing the electronics. This guarantees protection for sensitive electronics found on these vehicles.
This wire provides the power to the trailer lights. Green/RT, yellow/LT, red/brake, and brown/tail lights going to the power converter are only used as a signal. Once a function is used on the vehicle, the converter provides the actual power for the trailer lights from the battery. This allows you to bypass all the vehicle electronics to provide guaranteed safety.
Check all wires for bare copper or places where a wire could be pinched and calculate the amp load your trailer is pulling. Most vehicles are equipped to handle only standard lighting on trailers; one turn/brake signal on each side and one marker light on each front corner. Check your vehicle owner’s manual for specific ratings.
Yes, you should always unplug your boat trailer when backing into the water. When the trailer lights are submersed in water, it can create a short causing vehicle fuses to blow and/or result in damage to your wire harness and vehicle.
You have a ground problem. In your situation, you have a ground that is strong enough to provide some lighting functions but not all. This is called a weak ground. When the tail lights and brake lights are used at the same time, it creates the maximum amp load of lights on the trailer. If a ground problem exists, it will show at this point. The places to check grounds are as follows:
1. The connector on the vehicle should have a ground wire secured tightly to a clean surface on the frame. A wire attached to the body or a surface with undercoating or rust can cause a ground problem.
2. The connector on the trailer should have a wire from the connector secured tightly to a clean surface on the trailer.
3. Each tail lamp assembly at the back of the trailer also must be grounded. This is done in one of two ways. The first is by a separate wire coming from the back of each tail lamp assembly being secured to the frame. The second, and most popular, ground is achieved through the bolts of the tail lamp assembly. In this case, the lamp housing must be attached to the frame of the trailer. If the lights are mounted on wood or PVC material, the light will not receive ground.
4. The last possibility to explore is in the trailer design. If the trailer has a tilting bed, it is possible the ground is not passing through the pivot point resulting in a poor ground. The solution to this is to route a ground wire from the connector at the front of the trailer to each lamp assembly at the back of the trailer bypassing this pivot point.
NOTE: The trailer hitched to the ball of the vehicle should never be considered sufficient ground.
This is usually related to one of two things. The first could be a short somewhere in the system. All wiring and the vehicle connector should be checked and tested. The second, which is the most common problem, is a weak ground in the system. Refer to the above question and follow steps one through four.
When you add trailer lights to a vehicle system, the turn signal amp load basically doubles. Most vehicles have a flasher that controls the blink of a turn signal. The standard flasher provided in many vehicles will not handle this extra load. You should replace your flasher with a heavy duty one (8 to 10 amp) and make sure the vehicle engine is running. The flasher will slow down your turn signals and a running engine will increase brightness of the lamps.
A time based brake control sends out your adjusted power setting over a set time frame with each depression of the brake pedal, regardless of how hard you press or how long you hold the brake pedal. A proportional controller activates the trailer brakes according to how much braking force was created while braking your vehicle. This ensures that the brake control is proportionally sending the same amount of power to the trailer brakes mirroring the braking of the tow vehicle.
Occasionally apply di-electric grease to all electrical terminals to prevent corrosion and ensure good continuity.
When testing to see if trailer lights are functioning, ensure that the trailer is connected to the ball mount of the vehicle hitch.
Always check all trailer lights before towing to ensure proper operation.
Always check battery level of the breakaway system before towing.