This post contains affiliate links. Read the full disclosure here.
How to set up a dinghy vehicle’s electrical system for safe, trouble-free towing
When you tow a vehicle behind a motorhome, you have to consider that you’re essentially treating the car like a trailer, and it should function like one in order to ensure safe, lawful travel. In the last two installments of Dinghy Digest, we presented information on baseplates and tow bars that make hitching and towing possible — so now it’s on to the next step: the electrical system.
Unlike a trailer, which has a power cord designed to plug into the tow vehicle to provide power for running/brakelights and turn signals, a car/truck/SUV doesn’t, so one must be wired into the system. The most common way to do this is with a wiring harness that plugs/splices into the dinghy vehicle’s tail- and brakelights and uses one-way diodes to prevent electrical feedback. For those who prefer not to tap into the existing wiring, a bulb and socket kit can be used, which bypasses the towed vehicle’s lighting circuit and is mounted inside the taillight assemblies. In either example, the wiring harness is routed to a receptacle mounted at the front of the vehicle, and a specific power cord is plugged into the dinghy and motorhome, in a similar fashion to hooking a trailer to the tow vehicle.
Years ago, those were your only two options — but today, there are even easier alternatives. Blue Ox, Demco and Hopkins Towing Solutions offer vehicle-specific wiring harnesses for popular vehicles that allow you to plug into the factory harness, eliminating the need for cutting and splicing. These same companies offer fit lists that make it easy to determine if a vehicle-specific kit is available for your application.
If you tow more than one vehicle, or just want the easiest lighting solution, you may prefer an auxiliary light system that attaches temporarily to the vehicle. Roadmaster’s Magnetic Tow Lights and Demco’s Light Bar are self-contained systems that require no internal wiring of the dinghy vehicle and simply plug into the motorhome’s 7-way receptacle to sense lighting sequences. There are even products on the market that use Bluetooth technology, eliminating external wiring.
Obviously, not all vehicles have the same electrical systems, and you’ve likely noticed procedures in our annual Guide to Dinghy Towing that may be required before towing, usually to prevent the dinghy vehicle’s battery from going dead while in transit. These may include disconnecting the battery or removing specific fuses, which is far from convenient, especially for those who tow frequently. A specific kit allows you to effectively disconnect the battery while towing by simply flipping a switch in the vehicle’s cabin — and if the dinghy requires one or more fuses to be pulled before towing, Roadmaster offers its FuseMaster kit, which effectively disconnects the fuses in question with the push of a button.
In cases where the vehicle draws current while being towed, or you are using a supplemental (dinghy) braking system that runs off of the dinghy’s battery, a charge line kit can prevent discharging (and surprises) when it comes time to disconnect. A charge line kit is designed to keep the dinghy’s battery charged from the motorhome while in transit, in much the same way a trailer’s battery is kept charged by the tow vehicle. However, this can only be effective if you know the amount of current the vehicle and its accessories are drawing, so that the proper gauge wiring is employed. We should also mention that a charge line kit should not be considered a substitute for disconnecting the battery or removing specific fuses if that’s what the owner’s manual calls for.
Blue Ox | 800-228-9289
Demco Products | 800-543-3626
Hopkins Towing Solutions/Hopkins Manufacturing Corp. | 800-835-0129
Roadmaster Inc. | 800-669-9690
Popular RV Rentals