Why Cant Trailer Wiring Brake Signal be Used When Installing Brake Controller

Question:

2017 Toyota Highlander without factory tow package. I have a bit of pre-history before the question, please bear with me... Redarc recommends wring the unit to the Brake light terminal of the trailer plug rather than Brake Pedal Switch and using a diode to prevent back feeding of the current. That way all braking events will be captured like downhill assist and emergency breaking instead of just depressing the brake pedal. This recommendation makes mounting point near the hitch plug rear of the SUV a more convenient place for the device. But the remote cable looks like it is just a simple CAT5 network cable is too short for this type of installation. So the question I have is: Can I use a regular CAT5 cable as a replacement of the supplied one or is there a length limit on that cable?

asked by: Nick

Expert Reply:

The problem with using the brake light circuit of trailer wiring when installing a brake controller like the Redarc Tow Pro part # RED44FR is that trailer wiring has the stoplight and the turn signals on the same wire. So your controller would think the brakes are on everytime you used the blinker. That's why you have to get a dedicated brake signal for the red wire of this controller. Typically people will find this at the brake pedal but if you wanted to find this circuit at the rear of a vehicle you could use the third brake light signal too.

Redarc is an Australian company and their trailer wiring is possibly different than our standard so that's why they may recommend a different approach.

The type of cable that connects between the module and the dial is CAT5 and there isn't a length limit.

expert reply by: Jameson C