Green/Yellow wire, what is it for?

I am replacing my external circuit breakers and bus bar due to corrosion but am also trying to figure what the breakers go to.
Left to right:
#1-30A to operate jack when hooked up to tow vehicle.
#2-30A Slide.
#3-10A green/yellow (or yellow/green) can't figure out what it operates.
#4-50A to operate jack from trailer battery.
I've turned on all appliances, lights etc. and everything works as far as I can tell. Only thing I couldn't check were the trailer brakes. I've seen photos with a green/yellow wire they don't say what it goes to. The breaker is only 10A so it can't require too much power. Searched all over, and can even find the green/yellow wire for sale but that's it. Any suggestions? Thanks.

Jim Hanus

Trailer brakes use a blue wire. I don't think it utilizes a fused or breaker.
Have you checked the furnace, AC and refrigerator?

Peace
Dave

The breakers are 12V on the bus bar so no on the A/C which is 120V. Furnace works fine as well as refrigerator.

Breakaway switch?


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Breakaway switch is a red wire.

There's no color standard for this kind of thing. E-brakes are usually blue but even that's not a hard rule. It's obviously 12V power to something, but you'd have to trace the wire to find it. It could be an optional accessory that you just don't have installed.

If you have an under-belly area, try removing trim panels, or in your kitchen, look behind cabinets and under bottom drawers to get access to where they usually hide slide, awning, jack, and other controllers like that. You might find an empty wire just hanging around there going nowhere, in which case you can probably repurpose it for something else, like more outside lighting (LED spots/floods/rope lights around the edges or entry stairs?). I like to add a few extra cigarette-lighter plugs in my campers, which are useful for USB chargers (cigarette-lighter-USB-chargers are dirt cheap) and accessories like tire/ball inflators.

That looks like 10AWG so it should be good for a fair amount of draw. Be sure to use a DC ampacity chart, they're different than the AC ones Google usually returns. It should be good for at least 10-15A depending on how long the wire is. (My chart says 10AWG in "free air" is good for 5A up to 60', 10A up to 30', 15A to 20', or 30A up to 10'...)

In my current camper I added a pair of bulkhead SAE power ports, one on each side, and I use them more than I ever thought I would. I made up cords for a tire inflator and a spare RV water pump. I use the pump with an Aquatank bladder and a garden hose to refill my fresh tanks while boondocking, and it works great. I also have an LED rope light for my patio area, I got a 12VDC version and it's more efficient when boondocking than running your typical 120V strand off the inverter or generator. My wife suggested we get a 12V fan too, and we'll probably do that this summer - on super hot days it's nice to move some air around especially when the sun hits the dark side of the camper and it becomes a radiant heater... If you're the type who might have/like a small boat with a DC trolling motor, you can use the port to charge that battery, too, which is pretty handy. I can probably think of a dozen ways to use an extra wire like that...

I have installed various 12V outlets and USB ports already, as well as installing a second water pump to fill my water tank when boondocking (that's all we do). I have pulled underbelly panels and poked around without success (the fasteners used are driven in with an impact driver of some sort and are a bear to remove). It's a 12V breaker, and I've contacted Heartland who pulled up the drawings for this unit based on VIN and don't show it. I'll probably leave it disconnected next trip and hopefully see what doesn't work.

option is to borrow/buy circuit finder to find where it goes. I've used them & they do work tracing wires circuits

Trailer brake wiring should not be connected to the 12 volt circuit breakers buss area since DOT doesn't want a tripped breaker to prevent the emergency electric brakes from activating in a trailer disconnect situation. The risk of an electrical fire in the trailer brakes wiring is considered less of a threat than a runaway trailer rolling down the highway.
There IS a 12 volts DC charging wire coming from the truck through the 7 pin umbilical cable connection to provide trailer battery charging while travelling, specifically to keep the trailer battery system charged for a possible trailer emergency brake activation. The 25 amp fuse in my truck for this wiring kept intermittently blowing causing removal of the travelling charging current WITHOUT ANY INDICATION IN THE TRUCK OR TRAILER THAT THIS HAD HAPPENED. Judging this problem to be the result of an intermittent high 12 volt current draw in the trailer that I could never find, I installed a 20 amp SELF RESETTING circuit breaker in this charge line at the umbilical cable connect box at the trailer hitch.
Several years later the battery charging function from the truck seems to be working correctly.
I am sure that there is normally no fusing of the disconnect circuit, as I have read more than a few postings of the disconnect switch being accidentally turned on while the trailer was parked, and the switch itself eventually burned out.
If you suspect that this wire might be the charging wire from the truck (or that the truck fuse might be blown), hook a 12 volt DC voltmeter to the trailer battery, disconnect all AC power from the trailer to disable the charger/converter, take a DC reading on the battery, connect the umbilical cable to the truck, start the truck engine, and take a 2nd trailer battery voltage reading. If the truck is providing charging current to the trailer through the umbilical cable, the 2nd reading should be greater than the first.