There's a 20 Amp military breaker on the firewall that I added to power the 24-12 volt converter thats on the firewall in the cab under the glove box. That has two sets of outputs. One to a 12volt receptacle with a cover that I added to a bracket next to all the switches on the dash AND another lead runs to a tekonsha brake controller (first to another 20 amp breaker on the firewall in the engine compartment). The brake controller needs a lead into it to signal when brakes are applied so it know's when to actuate the brake and by about how much due to the slack. So I added a second brake light switch which is powered by the same 12 volt lead from the.
YOU MUST ADD a second brake light switch. Putting 24 VOLTS into the Brake Controller will probably kill it. I added a second AIR type switch to the air pack. This system relies on power to work so if you have non functional electrics for some reason, don't expect trailer brakes.
The better inertia type controllers use an accelerometer and are more correctly sensitive to force needed for stopping. HAving it under the dash right next to your knee is handy as you can reach down and actuate the brakes manually with the lever under the controller.
The Brake Controller also needs a dedicated line of sufficient wire gauge TO AND FROM the brakes (Blue and White). I ran this through a separate connector as I was worried about soldered connections on the inter-vehicular cable not being able to handle up to 20 amps of load on the 14 gauge wires. I ran, iirc 10 gauge wire all the way back to the Additional plug which comes out next to the inter-vehicular socket.
Inside the large grey box is a set of terminals so I could easily connect the wiring for the Brake Drums, breakaway system and intervehicular cables to terminal blocks and keep them tidy. The terminals also provide for a very handy TEST Point to diagnose problems. The box has penetrations that are sealed with foam to prevent water ingress but still has a tiny breather hole in the low side to allow any condensation to drain out.
I might convert lead K/#37 to a 24 volt lead and add a small amperage 24-12 volt converter in the box so I can use the Deuce to tow military trailers that'll need 24 Volts on K/#37
Squirt Truck has a similar setup but he stuffed the brake controller and a voltage converter inside the electrical box and added an airswitch there with an Air line to the back of his truck. This allows him to put the trailer behind ANY truck but cannot quickly adjust the brake controller for the amount of weight. He also can't tell if there's a problem.
The Brake controller in the cab is handy as stated because you can manually apply the brakes (say on a long down hill run), see if everything is connected (it tests for resistance to the trailer brakes, and gives an error if it's too low) AND it also displays braking Voltage applied while stopping.
I decided that as complex as this is, it needed a proper schematic so I whipped one up.
