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Troubleshooting Trailer Wiring and Frequently Asked Questions


Q: What is a converter?
A: Two types of taillight 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 taillight design is common. If the brake light and turn signal 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 system, which is required on a trailer. A converter enables vehicles with independent brake lights and turn signals to provide proper lighting to the trailer.

Q: Why do I need a power converter?
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.

Q: What is the reason for the battery lead wire on the power converter?
A: This wire provides the power to the trailer lights. Green = right turn, yellow = left turn, red = brake, and brown = taillights. These are going to the power converter and 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 it to bypass all the vehicle electronics to provide guaranteed safety. (Not all converters bypass through the battery).

Q: I am blowing fuses in my vehicle.
Check all wires for bare copper or places where a wire could be pinched and touching metal on the trailer or you tow vehicle's chassis/frame. If that is ok, then 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 power ratings. If it is not a short, a pinched wire, and your vehicle is rated to supply the necessary number of amps (power), then consult a professional.

Q: Should I unplug my boat trailer when I back my boat into the water?
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.

Q: When I have my headlights on and apply the brakes all my lights on my trailer go out. What causes this?
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 taillights 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 on a clean surface to the frame. A wire attached to the body or a surface with undercoating, paint, 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 ground. This is done in one of two ways. The first is by a separate wire coming from the back of each tail lamp assembly and 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 lights 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 hitch & ball connection area should never be considered sufficient ground.

Q: When I use one turn signal the other one blinks.
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 andmost common cause is a weak ground in the system. Refer to the above question and follow steps 1 through 4.

Q: When my trailer is connected to my vehicle the turn signals are dim and flashing rapidly. What causes this?
A: 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 flasher (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 the brightness of the lamps.

Q: Will the converter work in reverse for vehicle-to-vehicle towing?
A: No.

Q: Will these converters work on a 24 Volt system?
A: Check the converter description. Most will work on 9-24 volt systems.

Q. Trailer Wiring Diagram for 6 pin & 7 pin Conductor Plugs
A. Here is the Diagram for 6 & 7 Pin Plugs - Click Here.

Q. Trailer Light Amperage Guide?
A. We have a basic Guide available for referance Here.

Q. What is the difference between a Custom Wiring kit and Universal Wire Kit?
A Custom wire kits often times are a plug in style, so no splicing or direct wiring. In some Universal wire kits, splicing of wire is required. You also need to understand more about the electrics of your vehicle to correctly connect the wiring kits. Directions are supplied.

Q. How do I know What I need?
A. Hopkins Manufacturing has a great diagram and information to help you better determine what you need so you can look for the correct verbage and terms. The Hoppy Understanding your Towing Needs Guide will be very helpful if you're a little unsure what you need to purchase, or if you need multiple wiring kits.

Q. Difference between Vehicle with Tow Package and with out?
A.Some vehicles have a "towing option" installed while others do not. You can tell if you have the "tow option" by looking at your vehicle wiring harness where it connects to your tail lights (you might have to partially disassemble one of your tail lights to know for sure). Vehicles WITH the tow option have plugs that connect/disconnect the wiring harness from your brake/tail lights so you can install a trailer wiring kit. If your vehicle does not have these plugs then the wiring harness connects directly to your brake/tail light assembly (a "hard wired" connection) - it does not have the "tow option" installed. If you are Unsure, please refer to your Owners manual or local dealership. We Carry Both Types.


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