Hooking up brake wiring

[Capebuild]

[quote][/quote]

troubleScottie, this brings up a question. I'm certainly not there yet (hooking up the 3rd brake light bar)..... but if I did not intend to have that 3rd brake light showing right and left turn signals and if I wanted it to just be a brake light, would the wiring set up you referred to still be needed? How would that LED brake light bar be wired in? I was planning on just tapping off the brake light wiring.....
I think maybe I'm missing (not understanding) something here.

Just want to be prepared when it does come time to plan and hooking up the 3rd brake light wiring.

Thanks for the help.

John

[Tom&Shelly]

troubleScottie, this brings up a question. I'm certainly not there yet (hooking up the 3rd brake light bar)..... but if I did not intend to have that 3rd brake light showing right and left turn signals and if I wanted it to just be a brake light, would the wiring set up you referred to still be needed? How would that LED brake light bar be wired in? I was planning on just tapping off the brake light wiring.....
I think maybe I'm missing (not understanding) something here.

Just want to be prepared when it does come time to plan and hooking up the 3rd brake light wiring.

Thanks for the help.

John

Hi John,

I didn't notice this either, until I started wiring: The brake light wires coming off of the tow vehicle are the same as the turn signals. So if the left one is flashing, it's a left turn signal, if the right one is flashing, it's a right turn signal, but if both are on steady, that's your brake light. Works okay as long as the turn signals and brake lights are the same bulbs (or LEDs) on the back of the trailer, which they usually are. We wanted a fancy set of lights with separate red brake/running lights and orange turn signals.

The solution was a 2 wire to 3 wire converter like TroubleScottie mentions. That box senses when only one of the signal/brake lights was on and when they both are on and outputs a separate left turn signal, right turn signal, and brakes.

Now our third brake light does not have turn signals. It has a set of dim LEDs that are wired to the running lights (along with the side marker lights and the running lights on our rear light set), and a brake light that I wired into the output of the 2-3 converter box along with the rear brake lights.

I'm not sure, but it seems to make sense to me that there should be a version of the third brake light that simply has the running light, and a left and right set of lights that would wire directly to the left and right turn signal wires that would indicate left and right turns, and brakes directly. Those would have four wires, including ground.

Tom

[Capebuild]

Thanks for the follow up and explanation, Tom. I need to give this a little further thought. Not sure I'm understanding it all yet. I'm going to grab a screen shot of your post and troubleScottie's post and when I get to planning the 3rd brake light I'll have it to refer to.

Thanks again.

John

[orourkmw]

I'd like to piggyback on CapeBuild's thread, as I've run into a problem. I have a 2022 F350 with a 4-way plug to my camper. All my trailer lights worked until I went to hook up my Third Brake Light. I realized that since a single signal combined each turn signal with its stop light, I would have to split the signals out. I initially purchased a Red Wolf 2-wire-to-3-wire converter, and hooked it up per these directions from etrailer.com:



Although my "low" taillights worked as before, incl blinkers and brake lights...that's only when the brakes were not applied. When the brakes are pressed, the converter buzzes for as long as the brakes are on. When a turn signal is activated in conjunction with the brake being applied, the Third Brake light flashes in time with the turn signal....and the opposite turn signal is activated! If turn signals are not activated and the brake is pressed, the Third Brake Light (and low taillights) all work, but the relay still buzzes.

Because of the buzzing, I thought perhaps I had bought a defective converter unit. I then bought a Curt model....same result. My friend said I should connect it per the "vehicle side" instructions that were the same for Red Wolf and Curt:


In the initial setup, the converter was simply used to extract the brake signal, and not send the turn signals to the Third Brake Light. In the second setup, obviously, it all goes through the converter. However, that approach failed, too.

I have a friend with an older Dodge Ram, and the relay does not buzz when my camper 4-way is connected and brakes applied, but it still doesn't work correctly. However, there must be some difference between Ford and Dodge wiring.

I don't know what to do next....google hasn't been a lot of help, though I did find a diagram that showed a diode in-line.....any ideas?
Mike

[steve cowan]

Looks like you've wired as per instructions.One question is the 2 to 3 way on output side doesn't show a ground wire but would assume that you have grounded your 3rd
brake light?Most of these lights are red=brake black=turn and white=ground.

[orourkmw]

Thanks, Steve. Indeed the fixture is also grounded.
Mike

[orourkmw]

Another data point....I found elsewhere on etrailer.com where one person posted a similar problem. The answer was that the green and yellow wires had to be connected to provide the needed resistance in the circuit. So they recommended running a separate signal wire from the tow vehicle to the Third Brake Light, which is not practical. I tried the etrailer setup, but connecting the (previously stubbed) green and yellow wires to the low taillights, as well as to an external pair of temporary taillights, with no proper result in either case. When fed to the low taillights, it was like before....when brakes applied, converter buzzed, Third Brake light and low taillights activated. When blinker turned on, buzz would coincide with flash, and Third Brake Light would flash. At least the proper taillight flashed.

When the temporary taillights were connected, the same result, except the opposite temporary light flashed (yes, I'm sure I had right and left correct).

I'm still trying to find info about the need for a separate diode...though I thought that's basically what the converter box is. None of the instructions mention it.
Mike

[Tom&Shelly]

Only idea I can suggest right now is that maybe the converters were designed for incandescent lights and you are using LEDs? If so, they may want to see more current draw from each light. Do the directions say anything about being for incandescent lights only?

FWIW, the 2 to 3 wire converter I bought did say they were designed for incandescent lights, but I found they worked fine with LEDs.

Tom

[orourkmw]

Tom:
Thanks for the reply. I have been unable to find a converter that states it is specifically compatible with LED. However, Curt states their model 118158 is for incandescent. Etrailer recommends, and many people have reported success, with using Curt model 56196 with LED. That is the model I have. Curt does not confirm that model works with LED. I also tried putting some 166 ohms of resistors in line before the Third Brake Light, without success.
Mike

[MickinOz]

I don't have a lot of experience with this, apart from trying to fix someone else's screw-up once.
But this much I do know.
If you want to increase the current to make your LED look more like an incandescent bulb, the load resistor must be wired in parallel. i.e. not in-line (series).

Resistor.JPG (15.66 KiB) Viewed 367 times

The other thing of course is that your 2 to 3 wire converter is not seeing all the connections it was designed for if you have the yellow and green output wires capped. I would try getting two motorcycle turn signal load resistors and connecting one to each of those wires, with the other end of each resistor to ground. Those resistors are designed to put the appropriated load on a motorcycle flasher can.

[orourkmw]

Thanks, MickinOZ. I'll give it a whirl and we'll see what happens.
Mike

[orourkmw]

Success! but I'll get to that in a minute.

It seems motorcycle resistors are commonly 6 ohm, 10W units for a single light. My taillights are each actually an 11-LED unit, so I wired inline some 100 ohm resistors that I had on hand, between converter and ground on each of the yellow and green output wires, with no good result. (I calculated resistor value as {12V battery voltage - 2 V LED voltage divided by LED current}, which is listed by manufacturer as 0.06A, so would actually equal 166 ohms).

However, I finally got everything to work, per the original e-trailer "capped off" wiring model. It turns out in will not work on my Ford truck, but will work on another vehicle! I'm not sure, but I'm wondering if Ford is using PWM (pulse width modulation) wiring. I don't know exactly what I'm talking about, but I found a reference to it....PWM varies the signal intensity between the brake and the turn signal, which may be confusing the 2-wire-to-3-wire converter. Curt does offer a PWM converter, but I'm not intending to pull the camper with my truck, so I'm not going to worry about it for now. Here is an explanation of PWM and other converters from the Curt website: https://www.curtmfg.com/learn-more-tail-light-converters.

Curt's PWM converter costs >$100, and is much more complicated to wire in. However, Curt does state that more and more vehicles are going to PWM, so at some point....

I'm really happy that I will be able to use the Third Brake Light. Thanks to everyone who had ideas,
Mike