To safely tow a vehicle, and to meet legal requirements, the vehicle must have working tail, brake, and turn-signal lights. This can be accomplished by several methods.

• Diode kit - tap into existing tail-lights.
• Add on kit - add new light bulbs into tail-light housing.
• Temporary lights - magnet mount on vehicle (wired and wireless).

Of the three methods, the diode kit presents the most risk as you have to tap into the vehicle's lights. This may work OK for older vehicles, but modern vehicles with LED lighting and other sophisticated lighting systems (some use a modulated signal), you run the risk of damaging your vehicle with the diode kit.

One diode kit would be required for each light bulb. The idea of the diode kit is that either 12V from the vehicle or the motorhome will turn on the light bulb. The diodes prevent the voltage coming from one source to enter the other source. While this is an acceptable electrical engineering practice for incandescent light bulbs - especially on older cars - you can get into trouble with newer cars having LED tail-lights, or if you wire the diodes incorrectly.

The bulb-kit on the other hand completely isolates the motorhome from the vehicle - except of course the ground point. The advantage here is there is no risk in damaging the vehicle or motorhome electrical circuits, and you do not have to tap into the vehicle wiring. The disadvantage is that not all tail-light bezels have sufficient clearance for an additional light bulb... and you may also comprimise the waterproof characteristics of the bezel.

The third method is to use a portable light kit. These are available in wired and wireless versions. The tail-light assemblies have a magnetic base so you can place them on the trunk of your vehicle. The advantage of this system is you do not have to do any modification. But there are disadvantages in the possible marring of the paint finish of your vehicle, running out of batteries (the wireless versions are typically powered by dry cell batteries), or routing the wire from the tail-lights to the front of the vehicle.

As well, the portable kit requires a few minutes to attach each time you tow the vehicle, which can be a disadvantage if you tow often.

One out-of-the-box thinking idea I had was to put a trailer hitch on the towed vehicle, and attach a hitch-mounted bicycle rack. Then (since I have a welder), fashion a couple of brackets that could be folded against the bike rack (for easy stowage), that would deploy when towing to provide a mounting location for the tail-light. Such an arrangement could use a tail-light with a magnetic base, or permanently mounting the lights onto the bracket.

I decided to go with the Blue Ox BX8869 light-bulb kit for the tail-light bezel. It provides a permanent solution, and alleviates the need to tap into the vehicle's electrical system. The video below details the installation:

The 6 way connector can be wired two ways. One way is for a 12VDC accessory (center pin) while the second way is the center pin being used for backup lights. Both configurations are acceptable. However, since it is not wise to backup a towed vehicle when connected to a RV (damage is likely), there is no need to have a backup light function.

The highlighted portion of the schematic is covered in this segment of the project. The remaining schematic will be covered in later steps.