Electrical change to brake - will this cause a problem?

[TravelHabit]

Not sure where to put this modification. I'd like to hear what others think of it and whether it could cause damage to the brakes, trailer, or TV. This video (starting about about 2:53) got me thinking that what I did might be a problem but I can't understand the reasoning behind the warnings given.

I wanted to be able to activate the trailer brakes via a switch. This is for short term and temporary use only in situations where I don't want to pull out chocks to hold the trailer. Primary example is when I return from a trip, and I'm a short distance from home, I like to pull to the road side and release my WDH while the truck and trailer are aligned (I have an Anderson hitch). The whole process is less than 5 minutes. One time I did this and forgot to remove the chocks! No trailer damage - just a set of plastic chocks now with asphalt sanded bottoms. Well never again - I though why not use the trailer brakes instead of chocks?.

Of course stepping on the brakes in the truck will activate the trailer brakes but I wanted to do this from the trailer itself. Another option is to pull the emergency brake pin but that is not advised and I don't want to mess with the that device.

The emergency brake did give me an idea. This wiring is very simple. A wire from the battery positive (which is also connected to the 7 pin plug black power line) is sent to the emergency brake device. This is then routed back to and connects into the blue brake line. The emergency brake pin holds two contacts open. If the trailer is pulled away, the pin is pulled, and the contacts close causing the brakes to be activated in full.

My thought. Install a parallel circuit with a switch to perform the same function. That is, a wire from the battery to a switch and then to the blue brake wire. I can then flip the switch to activate the brakes without touching the emergency brake device.

Simple enough. But I also wanted to be absolutely sure I didn't flip the switch and forget about it. So I uses a DPDT switch so when flipped on it would also activate a flashing light and clicker. The flashing light and loud clicking sounds will remind me to deactivate the switch/brakes before closing up the basement.


1st photo below of what this looks like at the panel basement. Switch is center top (high so that nothing accidentally hits and possibly activates the switch). Clicker is just behind panel where the very bright led light is mounted.


2nd and 3rd photo below shows what the A-frame electrical box looks like (3rd is just before the inline 10A fuse was put in and better shows the wiring). The first terminal on left is the battery negative/return and the second terminal is the battery positive terminal. Battery is upper right ring connector. Upper left ring connector is the wire to the jack which GD also crimped with the black line to the emergency brake. This then returns back to the brake terminal (#7 on the far right). When the pin is pulled power goes from the 2nd terminal to the 7th terminal. Emergency brake is the upper left ring connector to 7th terminal. Upper right goes to the brakes themselves. Lower left is from the trailer connector brake wire (blue). Lower right is my addition.



BTW, if anyone is interested, below is the original manufacture wiring. Notice the trailer cable isn't even clamped anywhere! One might recognize the 30A Optifuse (left of electric box mounted directly to A-frame) is not in the photo above. Rest assured this now is next to the battery inside the trailer to protect the wire routed from the battery to the A-frame box (2nd terminal upper right).

[acoleman43]

TravelHabit I've been considering this as well. The Aussie trailers all have a parking brake type handle mounted to the tongue of their trailers. In my opinion this is much safer as you can just pull the handle (or flip the switch) and the trailer won't roll away when you forget to chock the wheels (I think we've all done this).

I like the idea of a flashing light and clicking sound. If the trailer brakes were still engaged, you'd know it when you start pulling the trailer, but it will be a small drain on your batteries if left on while parked.

[ncitro]

TravelHabit I have always heard this is not advisable because you would be dumping full battery power to the brakes, rather than the proportional the brake controller in the truck sends out. In the case of an emergency brake away this is the least of anyones worries, and brake life is sacrificed for safety, but in your example I think there could be issues. The wiring could be overloaded, and the magnets could overheat as I recall. The brake wiring is not fused at the brakes (for obvious reasons) so if there were some kind of short near where the wiring enters the axle (a common occurrence) and you threw your switch you might have an issue as well. On top of all that I have not found the electric brakes to be as strong as I would want chocks to be anyway.

[Cate&Rob]

TravelHabit

No reason (that I can think of) that your plan won’t work. (Edit: See post #6)

Just a comment, if I may, on “not wanting to mess with the emergency break away switch” . . . this switch should be cycled on a regular basis, to make sure that it will work if needed. It will often need lubrication to work properly if it has not been cycled in a while.

Rob

[Jkwilson]

What you are doing is exactly the same as pulling the breakaway switch. You may not have much braking, as the braking force of electric brakes increases with wheel speed.

[Cate&Rob]

TravelHabit ncitro

Neil makes a good point that I had not thought of (by way of having EoH brakes, I guess )
Electric drum brakes need forward wheel rotation to apply the brake shoes to the drums. If the electro-magnets are powered up without wheel rotation . . . no brake engagement will happen until the trailer moves forward . . . which is probably not what you want!

Rob

[TedS]

It is correct that standard electric trailer brakes need forward motion to activate the brake shoes. The electomagnet is drawn against the drum, rotates with it until it bumps the actuator to force the shoes out to the drum brake surface. No drum rotation, no brake actuation even though the magnet is powered. So, activating the magnets while not moving will not act like chocks.

[TedS]

TravelHabit
Got a question. If you do not unhitch, why use wheel chocks at the trailer wheels? Putting the truck transmission in park should hold in most cases. Otherwise apply the truck parking brake to hold everything.

[howson]

Jared, in his video (Youtube's "All About RVs"), conveyed his experience when he accidentally ran the brakes for too long with the emergency breakaway switch. I believe he said the whole thing turned into a "hot mess". The heat is generated from the power being passed to the brakes by those relatively small wires. If there's any corrosion in the breakaway switch that will also cause an issue in the unit (probably what happened in his case).

Either way (pulling the breakaway or engaging using a switch) this should not be done with the 7-way plugged in to the tow vehicle (TV).

The Fastway Zip Breakway Cable manual has this Caution:



Honestly--I didn't know the 7-way was supposed to be disconnected from the vehicle prior to testing--just learned something. I'd overlooked this in previous reading of the manual.

The Tekonsha breakaway switch's manual is even more explicit with a WARNING:



TedS ' question in post 8 made me go back and read your post again. It is confusing why brakes would be needed if the trailer's not being disconnected. If the trailer is being disconnected from the TV, my .02 is take the time to do it right. Install chocks. (If the disconnect is only momentary you can still turn on your light and buzzer--without brake application--to remind you to remove the chocks when you're reconnected!)

Howard

[Jlawles2]

I remember reading a post somewhere a while back (probably not even this forum) where the poster was using the trailer breakaway to hold the camper while setting up. Needless to say, he forgot about having the switch activated and found it when he smelled the wiring starting to melt the insulation. Turns out most of the wiring in brake systems is undersized for full power over a longer period of time.

On a side note, if you are using the tongue jack to lift the rear of the truck (guess is to why you want to use the chocks) in case there is a loss of traction, you should be chocking the front wheels of the TV not the trailer. If you have a 4wd TV, put the TV in 4WD as you pull over and then apply the e-brake as this will loc all 4 of the TV brakes through the transfer case.

[TravelHabit]

What you are doing is exactly the same as pulling the breakaway switch. You may not have much braking, as the braking force of electric brakes increases with wheel speed.

Excellent point on the wheel speed factor! I hadn't thought of that. I'll have to test it to see if this will even work when parked (probably should have done that before running the wiring and installing Doh )

TravelHabit
Got a question. If you do not unhitch, why use wheel chocks at the trailer wheels? Putting the truck transmission in park should hold in most cases. Otherwise apply the truck parking brake to hold everything.

For extra safety. To release the tension in the Anderson hitch I use the jack to lift the trailer AND rear of the car. This inverted V releases the tension in the chains. However doing this puts a tremendous weight on the Jack (as well as the tongue lock) and I'm thinking lateral movement due to rolling could over stress something. Does anybody know if this force on the tongue lock is a problem? Since it was designed to hold the ball to the tongue it's not clear if it can withstand the extra weight of the jeep.

I remember reading a post somewhere a while back (probably not even this forum) where the poster was using the trailer breakaway to hold the camper while setting up. Needless to say, he forgot about having the switch activated and found it when he smelled the wiring starting to melt the insulation. Turns out most of the wiring in brake systems is undersized for full power over a longer period of time.

On a side note, if you are using the tongue jack to lift the rear of the truck (guess is to why you want to use the chocks) in case there is a loss of traction, you should be chocking the front wheels of the TV not the trailer. If you have a 4wd TV, put the TV in 4WD as you pull over and then apply the e-brake as this will loc all 4 of the TV brakes through the transfer case.

Thanks, I do have full time 4WD but good point anyway. Though the rear wheels don't leave the ground their traction would be greatly reduced. I get you on the wiring. I noticed the wire was very thin and wondered about that. It's one reason I added an inline fuse to this path. I selected the smallest fuse that would work (both the 3A and 5A fuse blew immediately when tested!).

...Honestly--I didn't know the 7-way was supposed to be disconnected from the vehicle prior to testing--just learned something. I'd overlooked this in previous reading of the manual.

The Tekonsha breakaway switch's manual is even more explicit with a WARNING:


...
Howard

I was wondering about the break controller seeing a reverse voltage... I had it in my mind to contact the manufacture to see if this would be a problem. My controller is a Redarc. It is made in Australia so given what @acoleman43 said perhaps it is the exception to the Tekonsha warning?

Until I know for sure I'll certainly remove the plug.

[Jlawles2]

Install a SPDT (on-on) switch instead of the SP. With the SPDT you can set the incoming line from the 7 way plug to one pole, the battery to the opposing pole and the center to the battery. This way, it auto disconnects the TV when you flip the switch. If you do DPDTyou can wire the clicker and hazards to one side of the switch.

https://www.littelfuse.com/technical...nd-throws.aspx
in the 3 over 3 picture explanation the center ones.