How to wire a breakaway switch alarm??

[TundraTower]

Here's an interesting problem for the folks familiar with wiring challenges........from someone with skills on the mechanical side.

A few weeks ago we set up the travel trailer early in the afternoon and disconnected the truck, all as usual. About 11PM I was doing my night time check of things before going to bed and heard a hum that I traced to the brakes. Apparently I accidentally pulled the breakaway switch plunger out when I was trying to get the safety chains off the ground and the brakes had had full voltage for 11 hours. Luckily no damage that I can find.

I would like to install a horn or buzzer to warn me of this if (when) I make this same mistake again. I bought a simple back-up alarm for this purpose.

Initially I thought I could just splice this horn into the side of the breakaway switch that is energized when the plunger is pulled. However, this side of the switch is common to the wire that goes from your truck brake controller to the wheel magnets, so it is energized frequently from the other direction. IF I wire it the way I was thinking, it will beep when the plunger is pulled out, but it will also beep every time I apply the brakes when driving. That's going to be hard to explain to DW.

One solution would be a check valve (diode?) to prevent the normal brake controller voltage to come back up this wire to the switch, but I'm not sure they make diodes that strong (13V and 12 amps).

Anyone ever done a modification like this, and/or have ideas on how to wire this in so the horn is only energized when the plunger is pulled out?

Thanks.

[robotworks]

While I won't hassle you about the necessity of this,I am an engineer who deals with safety hardware in complex systems and I will advise against touching the brake circuit all together. Unless you are using safety rated parts,, and have a clear bulletproof design, you can do much more harm than good modifying this important circuit. Something shorts out, you lose your brakes and you don't know it? Something shorts out and destroys the brake unit in your tow vehicle?
Think like a pilot. Check lists. I use one to make sure I forgot nothing when hooking up or unhooking the trailer. Every time. That came out of an incident where I didn't plug the electrical 7 pin connector in all the way and it fell out. In less than 1/2 mile I destroyed the connector cable between TV and trailer. Not hard to fix but sure screwed up that weekend.
I would also check that module that is attached to the safety cable. It should not easily pull out. Perhaps the spring that keeps the system from accidentally energizing is weak or broken within the unit.
tim

[hawkeye-08]

Bobbo wrote:
The only problem with the LED light concept is you have to go look at the light. You could just as easily go and look at the pin in the breakaway brake. There is no advantage to the light. With the buzzer, it will get your attention wherever you are. I like the concept of using a diode and wiring the ground side of the buzzer to the hot side of a brake light. It disables the buzzer when the brake pedal is pressed.

The concept of the light is that you would see it light up when you knocked the pin out. I'm expecting that your pin is not falling out when you are not there??

[Bobbo]

The only problem with the LED light concept is you have to go look at the light. You could just as easily go and look at the pin in the breakaway brake. There is no advantage to the light. With the buzzer, it will get your attention wherever you are. I like the concept of using a diode and wiring the ground side of the buzzer to the hot side of a brake light. It disables the buzzer when the brake pedal is pressed.

[Gdetrailer]

hawkeye-08 wrote:
How about a simple red LED light (one bright enough that it can be seen in daylight) instead of buzzer near the hitch so that you can see it. should not matter if it is coming on when braking normally...

^^^^THIS^^^^

Is the most intelligent post on the subject at hand.

It is dirt cheap and effective!

Much better than compiling "check lists" that do not address the "what ifs" that happen outside the scope of the check lists..

Besides, who in the world walks around with a bunch of checklists in hand.. This isn't like you are flying a airplane and must "document" all your preflight "checks"..

A dirt simple cheap LED light like a marker light can be connected to the blue brake wire.. When the plunger is accidentally pulled the battery voltage from the switch powers the blue wire and the little marker light lights up!

When driving, the marker light most likely will have some "glow" and will get brighter when the brakes are applied but WHO CARES!

Brilliant!

Should be some sort of award given for this one.

[hawkeye-08]

How about a simple red LED light (one bright enough that it can be seen in daylight) instead of buzzer near the hitch so that you can see it. should not matter if it is coming on when braking normally...

[GrandpaKip]

I use the spring coil cable and hook it to the bumper, so it is a separate operation to unhook. Then I put the coil and carabiner on the a frame where it can't be snagged by anything. On the plus side, the plunger on mine takes a pretty good tug to pull out.

[mobeewan]

Add it to your check list. If you don't have one you should. I have 2. One for unhitching. Some things are not needed right away and/or are only done when needed. It is very short. The other is for breaking camp and hitching up. It is much longer and includes undoing things I might have done after unhitching.

Okay 3 check lists. The last is for loading. I add anything needed to prep for a particular trip at the end of that list.

[TundraTower]

The plunger pulled out because we have the break-away cable laced thru the safety chain on that side. A dealer in Oklahoma gave us that suggestion to prevent the cable from dragging on the pavement. So as I re-arranged the chains I must have pulled on the cable.

Based on some of these replies I checked to see if there was a full moon last night. I'm all for humour in these discussions and certainly have to laugh at myself sometimes. However, if you Google the scenario in question its not unheard of and sometimes with catastrophic consequences. I thought sure someone on here would have an elegant solution.

Yep, I'm OC for sure and have tons of check lists for the "deliberate actions" as someone called them. But I also have tried to set up fail-safe's for things I would not normally touch or change consciously but still might happen. As I get older I find myself less and less aware of some of the little things, so have adopted the tact of "Trust but verify".

A time delay in my buzzer circuit would accomplish the goal without the nuisance beeps while traveling, but even I recognize that is getting too close to measure with a micrometer, mark with chalk, and cut with a chain saw.

Changing from a buzzer to a light is a really good suggestion. However, NMDriver wins the Duct Tape award with his suggestion to put the buzzer inside the trailer.

Thanks for your help.

[voodoo101]

Not sure how you managed to pull it but consider this cable. My old fiver cable had slack for turns and was prone to hook on things in the bed when doing tight maneuvering on uneven surfaces. This cable solves the problem. FWIW

[westend]

I'd use a switch with an LED indicator. If the OP is more "audio-centric", a buzzer could certainly be used. The switch will eliminate the buzzer or light operating when towing. A clever electrician could even wire in a switch that operates with the sequence of the trailer being hooked up to the truck (micro switch positioned on coupler/WDH/safety chains).

[mike-s]

troubledwaters wrote:
You going to add alarm for when you accidentally leave the antenna up. Or accidently leave a window open. Or accidentally leave the dump valve open. Or accidentally leave the step down. Or accidentally leave the water pump on. The list is endless. It's a one off thing. Do your due diligence and get on with life. Stuff happens.

Antenna up, deliberate action. Open dump valve, deliberate action. Put step down, deliberate action. Water pump on, deliberate action. You've done all those things, so it's up to you to remember.

Breakaway switch accidentally pulled, you don't know, and there's no indication to make you aware. Is checking the pin on your setup/teardown checklist?

Different things.

[troubledwaters]

You going to add alarm for when you accidentally leave the antenna up. Or accidently leave a window open. Or accidentally leave the dump valve open. Or accidentally leave the step down. Or accidentally leave the water pump on. The list is endless. It's a one off thing. Do your due diligence and get on with life. Stuff happens.

[mike-s]

A diode (like the common 1N4001), and a buzzer, wired like this. During normal driving, the brake lights come on when you're braking, so the brake circuit is never at a higher voltage than the brake light circuit and the diode will keep the buzzer from sounding. When disconnected from the vehicle, there's a path to ground via the brake lights. If you have LED brake lights, you'd need a low current buzzer.

You could even eliminate the buzzer (would need at least a 5 amp diode if your brake lights use bulbs), your brake lights would come on when the pin was pulled.

[RedRocket204]

I agree it is probably not needed as you will now remember it.

But, in the event you still want to connect a reminder device, what about just a simple visible LED light instead of a noise maker? Put the LED somewhere you will see it after you unhook.