There is a 7-way plug on the back of the coach for a trailer. However, only 4 wires are connected to it. I need to add the Auxiliary Power connection. This is a 12VDC always-on wire.
I can figure out which terminal I need on the plug. I can use a wiring diagram if I look on line. OR, I can check the plug on the back of my Jeep. I know the Jeep and my trailer are wired properly. Both the Jeep and the trailer were wired by the factory and they work.
The questions that I have are:
1)
What size fuse? I know to check the wiring size to be compatible.
2)
Where to connect it?
What I need here is some help thinking this through. Please.
Regarding question #2, there is a fuse block in the battery compartment in the right rear of the coach. I can pretty easily run a wire from the 7-way plug to the fuse block. There are some "SPARE" fuse locations marked on the block's wiring diagram. The question is which one to use.
The answer lies in how I will be using the Auxiliary power.
There are two uses.
One is for the interior LED strip lighting that I have installed in the cargo trailer. The lighting strips are on a pair of 3-way switches. One switch is located by each door. Also, the wire runs through a fuse block when it enters the trailer. So, any internal issue should blow the fuse here instead of the fuse on the tow vehicle.
The second use is for the trailer brakes. Here I need to explain. Yes, I know there is a separate connection on the trailer plug for activating the brakes. However, that requires a trailer brake controller located in the coach. Often that is located by the driver.
I use a different system. The brake controller is a "Tekonsha 90250 Prodigy RF Electronic Brake Control" that is physically mounted on the tongue of the trailer. It uses G-forces to activate the trailer brakes. It is a wireless system. There is a hand remote that plugs into a cigarette lighter outlet by the driver. The remote is used to a) set up and adjust the braking power, and b) manually apply the brakes. As an aside, if the remote is not connected, the braking system still works fine.
Physically, the brake controller has a 7-way plug that connects to the coach. Then, the trailer's 7-way plug connects to the brake controller box. The wiring for the turn signals, stop lights, and aux power simply flow through the brake controller (with the brake controller stealing a bit of power for its own operation). The brake controller sends power to the trailer brakes when activated by the G-force.
As an aside, the wireless brake controller allows me to change tow vehicles without a need to have a brake controller on each tow vehicle. And, DW did Not like the idea of an after-market brake controller being installed in her "new" Jeep. The DP does not have a brake controller. With this system I do not need to install one in the DP. The controller is already on the trailer.
So, back to the question on hand.
That being said, here are some of the conditions that I am trying to meet.
I need the Auxiliary Power to be on when the coach is running down the road, of course. This powers the brake controller and the trailer brakes.
I think i want the Auxiliary Power to be on when the Chassis Battery switch is ON. And, Aux Power off when the Chassis Battery switch is OFF. This would keep the chassis battery from discharging if someone accidentally leaves the interior trailer lights on.
I do NOT think I want the Aux Power to be controlled by the Ignition Switch being on or off. I want to be able to use the interior trailer lights without the DP engine running. Also, if the ignition is turned off in an emergency situation (run-away engine), I want the electric brakes on the trailer to still react to the G-forces of slowing down. Remember, the air brakes on the coach will still work for a bit.
I am not sure if I am over-thinking this, but I want to get it right. Once I figure out which set of conditions i need, then it should be a simple task of reading the fuse block wiring diagram and using a test light to determine which SPARE fuse location will work.
What am I missing here? Comments welcome!
Wow. Looks like I just wrote a short book.
I am all ears.