Trailer Light Indicators

D

damason

New member
Sometimes when trailering my C-Dory 25 a friend following me later says that my trailer lights are not working. :cry: This really concerns me as I want my lights to be working all the time. In the day time there is no way to tell if they are working or not. At night all I can see is the clearance lights.

I came up with an idea: Install LED lights on the trailer fenders to show the running lights, stop lights, turning signals, and emergency flashers. I bought the yellow/orange LED lights from Radio Shack. They have a 90 degree display angle and are pointed straight forward. They also help as clearance lights. I wired them into the trailer wires at the front of the trailer. I used heat shrink fittings to keep out water and corrosion.

LED Light Package data
RS_Package.jpg

LED Light and receipt showing cost of $1.99 per LED light
RS_LED_Bulb.jpg

Installation of LED lights
LED_Installation.jpg

Looking in the rear view mirrors
Mirror_View.jpg

When trailering day or night I can visually check my trailer lights anytime by looking back. The outboard LED light is a running light and the inboard LED light is the stop light, turning signal, and emergency flasher. :lol:
 
That'll be my summer project. It's annoying, having to run around the trailer to check lights, and I have a certain length 2x4 to press the brake pedal, all of which can be avoided!
 
So I assume these are wired in parallel to the lights. If so, this will indicate that the connection to the trailer wiring is solid but won't indicate that the lights are working. To do the latter, you would need something in series with the lights so that when a light filament is open (or a wire is open someplace in the circuit) OR something in parallel that only lights when there isn't a voltage drop across the filament. Then you would know when the lights are not working. VW does this somehow on their newer vehicles such that an indicator light comes on when there is an open in any light (they the owner has to figure out which light isn't working).
 
Roger, one old Volvos had a dash light that did that. Sometimes hard to figure out which light was out...

And with those lights on the trailer, you may need indicator lights to tell you if the indicator lights are working. :shock:

I think I'll just stop and check. If it's a turn signal that's out, you may get a "fast" blink on your dash indicator. If it's a brake light, the same may happen if you put the hazard flashers on. If it's the tail or running lights, you can see that on the trailer.

Lots of ways to kill that bird.

Neat idea though! :thup
 
AN easy wy to check trailer lights is to turn on the headlights and the emergency flashers. Walk around the trailer, and every light should be working. The emergency flashers activate the same lights as the turn signals and brake lights.
 
That "walk around" Matt suggested is important, especially for us older folks. You'd be surprised at what was forgotten: safety chain, lights, ladder, antenna up. And remember the favorite of the CHP: the break away wire. The walk around is one thing I try to remember.

After working with indicator lights for years, I think that they only show that the indicator light is working.

Boris
 
journey on":19xfakxp said:
That "walk around" Matt suggested is important, especially for us older folks. You'd be surprised at what was forgotten: safety chain, lights, ladder, antenna up. And remember the favorite of the CHP: the break away wire. The walk around is one thing I try to remember.

After working with indicator lights for years, I think that they only show that the indicator light is working.

Boris
Click to expand...

Amen...
there is a awful lot there of stuff that us old folk's have to remember and it get's awful expensive really fast if we don't. I hope everyone is having a super day.
 
We tow a Honda Pilot behind our RV at least 10,000 miles every year, plus towing boat trailers. We stop every two hours and do the "walk around"--also before we start off. Included in this is having the flashers on--which will indicate of brake and turn lights are working.-temp of tires, hubs and brakes, as well as checking the running great and hitch.
 
YES! I agree that you can tell that the trailer lights are working by doing a walk around. I do a walk around and check the lights when first hooking up the trailer to the tow vehicle. I also stop every hour or so and do a walk around to check that the lights are working.

However I cannot do a walk around while driving 60 miles a hour down the road. The Trailer Light Indicators are to give you a warm fuzzy feeling that they are still working while driving.

They are hooked up parallel to the trailer lights.

I hope this idea helps some of you C-Brats that would like this feature on your trailer.
 
It's been a long time since I took shop in high school, but wouldn't the circuit below let the led indicator be lit only when the trailer light is working? The led light and resistor are in parallel, and that parallel circuit is in series with the trailer light. The resister in parallel with the led means the led only gets the .001 amp (for example) it needs.

.........I--.001 amp led-------I
neg---I..............................I---trailer light---pos
.........I--.001 ohm resistor--I

This is after edit: I had trouble with spacing (this must be variable size font), in my drawing, so I've added periods (.) to make things align. Hope that makes it look like I want it to. Just pretend the periods are spaces, and the hyphens and I's are wires. This gets more confusing the more I try to fix it.

Oops, that should've been ohm instead of amp on the resistor.
 
Na Waga. Thanks for the info. Draw a schematic of the circuit and scan it into a picture on your computer or take a picture with your digital camera. Transfer the ditital camera picture to your computer. Include the picture of the circuit in your post. You will need to put the picture into your C-Brats Picture Album. If you do not have a Picture Album ask the C-Brats administrator to make one for you. Then this schematic will be very clear to all readers of this Forum.

I have worked many years in electronics and understand your circuit, however there are many people that do not know ohms from apples. Thanks again.
 
Here's a picture, I hope:

circuit.jpg


Fun, doing this with the GIMP (Graphic Image Manipulation Program).
 
"It's been a long time since I took shop in high school, but wouldn't the circuit below let the led indicator be lit only when the trailer light is working? The led light and resistor are in parallel, and that parallel circuit is in series with the trailer light. The resister in parallel with the led means the led only gets the .001 amp (for example) it needs."
Click to expand...

So, does this mean that the indicator only comes on IF the light is actually on too. So if the trailer light bulb burns out, the indicator light will not be on? COOL, if it works that way.

Sure looks nice either way though.

Harvey
SleepyC :moon
 
After reading the original post again, I realized his LED
light had a built-in resistor, and further reading based on Google
searches made me realize this is so because the resistance of an LED
is negligible, typically 22 ohms for a red LED and a turn-on voltage
of 1.8v in a circuit involving resistances in the thousands, so the built-in
resistor is needed to keep from burning out the LED. So I've changed my circuit diagram to include it:

circuit2.jpg


I had a lot of fun and spent more time than I probably should have
this morning, trying to figure out how big the resistor in parallel
needs to be. I'm hoping one of you electronics gurus can tell me
if I've figured it right. Given -

Vt = Voltage drop across the trailer light.
Vp = Voltage drop across the parallel circuit for the LED indicator light.
Vs = Voltage of supply = 12

Vs = Vt + Vp = 12

Let At = 3 be the amperes needed to light the trailer light properly,
with the voltage drop (Vt) no more that 2 volts. So the resistance
(Rt) of the terminal light is

Rt = Vt / At = 2 / 3 = .667 ohms

This means we must design the parallel circuit containing the LED to
pass 3 amperes as well.

Rr = Resistance of the resistor in parallel with the LED.
Rl = Resistance of the resistor in series with the LED = .0025.


The resistance of the parallel circuit (Rp) is given by

Rp = (Rl * Rr) / (Rl + Rr)

The maximum amperage (Al) of the LED light with resistor Rl in series,
according to the RadioShack tag is .0025 amps with a voltage drop
voltage (Vl) of 3, so the resistance of Rl must be no smaller than

Rl = (Vs - (Vt + Vl)) / Il = (12 - (2 + 3)) / .0025 = 2800 ohms

If the amperage necessary for the trailer light At is 3, and the
voltage drop Vt is 2 volts, Al is .0025 amps, Rl is 2800 ohms, then
the resistor in parallel must be capable of passing

Ar = At - Al = 3 - .0025 = 2.9975 amps

The resistance (Rr) of the resistor in parallel with the LED must
be no greater than Rl, or too much current will be forced through
the LED. The voltage drop (Vr) across the resistor in parallel
must be at least

Vr = (Vs - (Vt + Vl)) = (12 - (2 + 3)) = 7

This means the resistor in parallel must be no greater than 2800 ohms
and rated for 3 amps (rounded) and at least 7 * 3 = 21 watts, assuming
all my guesses are close.
 
smittypaddler,

the trailer under Journey On has 12 Vdc lights, so I assume that's what you're working with. I certainly don't know what the voltage is for the LEDs you're showing (and I admit I might have missed that.) but I had assumed that you would get 12 Vdc LEDs there.

Putting 2.3K ohms in series would prevent the taillights from showing. Lets see, the current at 12 V through 2.3 K ohms is 5 mA which seems somewhat low.

Boris
 
The way I hooked up the Trailer Light Indicators is parallel with the trailer lights. The connection is at the front of the trailer to keep the connections out of the water. My trailer is a Float On by Pioneer and has LED trailer lights. When I start out I do a walk around and check that all LED lights are working and again recheck when I stop for a break. The Trailer Light Indicators just reaffirm while I am driving that the lights are still working.

Being hooked up parallel if one of the LED trailer lights quit working while driving the Trailer Light Indicators would still show that everything is OK. However while driving I feel that there is a good chance if the Trailer Light Indicators are working the LED trailer lights are also working. :lol:
 
Dave,

If your LED indicator is indeed in parallel with the trailer light, it merely tells you there's current to the light, but it won't tell you if the trailer light itself is burnt out. Again, I'm not an electrician, so hopefully an expert will chime in.
 
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