Autonomous Trailer Brake Lights?

Maybe, but a light-sensitive device taped to the car tail light lens is much less high-tech! The trailer must already have a cable + plug, no?

Mike.

Stick a photodetector onto the car's tail light.

It might be PWM'd, with some AC component. You might check that. It would help reject sunlight and such.

A liquid tilt sensor is easy to make and would act like an accelerometer. Add some corn syrup for damping. But mimicing the actual tail light is safest.

On a sunny day (Mon, 6 May 2019 08:59:56 -0700) it happened Mike wrote in :

Some sort of sucking cap with an LDR in it on your break lights as sensor? Piece of wire...MOSFET... lamp.

Or a 6 axis accelerometer? I am using some MPU6050 in a project, Raspberry Pi or a PIC micro, relays or MOSFETS to drive the lights.

Hmm for ~$50-100 I bought the wire harness I needed for our Toyota van, watched a video on youtube... 1/2 an hour later I was done. Unless you want to F-around with some other idea.

George H.

Just using an accelerometer won't keep the brakes lights on when you are stopped, which is kind of important. Also, what about turn signals? I think a photodetector on each brake light on the car plus some threshold logic to differentiate running light, turn signal, and brake light function would be a minimum.

keep in mind that while the wireless solutions are elegant if it's a commercial vehicle engaged in interstate commerce under the auspices of the FMCSA/DOT, DIY wireless or battery-operated lighting systems aren't generally DOT-approved; trailer lighting must be powered by the main vehicle power bus. or from a mfgr with a DOT exemption for their product.

If it's a personal vehicle it probably depends on local regulations.

Granted people seem to drive around these parts with all sorts of wackadoo clearly not DOT approved lighting and nobody seems to care too much.

Police are probably okay with it so long as nobody's using flashing blue, gives a fine pretext to pull the cars with that type of lighting over, should the need arise, as they're usually driven by the kind of guy who police like to take a look at from time to time. Sir I pulled you over because your lighting isn't...say what's that on the back seat looks like a drug baggie to me! Let's get the dogs...

Uber cabs sometimes seem to use blue LED signs in the front window which is a bit surprising

Point a wireless video camera at the back of the car and strap an LED TV set receiving the feed to the back of the trailer. It's like virtual reality!

now that's some outside-the-box thinking

Just buy a transparent plexiglas trailer.

Or use big light pipes.

The liquid accelerometer: water and corn syrup in a horizontal plastic coke bottle, with a spark plug in the cap. Adjust the liquid level so the plug electrode gets wet when you declerate.

I'd hack into the car wiring.

Light pipes could actually work. Pricey & bulky though. Maybe you could make some from $1 of space blanket. Oh, you would only need 2 pipes, one each side, each encompassing all the lights on that side.

NT

The brake lights have to stay lit when you're stopped with the pedal down, though.

Depends on the car, tapping the Volt's lamps would be easy, just have to unfasten two Torx screws and a Phillips and give it a firm yank and the whole tail lamp assembly easily slides out and off the frame for access to the bulbs and wiring harness.

Other cars you have to remove the bumper or a significant portion of the rear panel assembly to access the tail lamp wiring harness. Some other GM cars, even. The Volt has LED tail lamps and side markers but incandescent reverse, turn, and brake lamps. Design extremely sophisticated hybrid drive unit and then cheap out $10 on the exterior lighting. Well that's GM for you.

Well, F-ing around is what we do here.

Problem with buying a harness is that there don't seem to be any for the 2019. The ebay listing says for "19xx to 2019." But when you try to order it, it says it won't fit the 2019. I watched a youtube claiming that you just unplug a connector and put the harness in between. Problem is that it requires 12V. No problem, just hook it here on the

Per some of the other comments... The phone has the capability to "interpret" the accelerometer. Just leave the light on till it senses acceleration.

Putting a photocell on the tail light was my first thought, but I don't think that would be easy given the extreme range of intensity/sunlight etc.

I'll check some of the links provided earlier. Thanks

On a sunny day (Mon, 6 May 2019 17:56:04 -0400) it happened bitrex wrote in :

That is cool, play a video of a large truck approaching... Or display emoticons,.. ;-)

Or plan-B. Just drive around with your brake lights on. People here do that all the time.

But for some reason, they never seem to use their turn signals. :(

OK I don't know. Hey are you in the USA? If so, you should know you've got to buy a BIG truck if you want to tow anything. :^)

George H. (who tows his little boat with a mini van... not a real man. :^)

It also would not work properly on steeper hills, going up or down.

Take 2 new taillamps. Break envelope and solder wires to the pins. You can guess where the wires go to.

Remove LH taillamp, insert lamp with wires. Repeat RR.

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