Hooking up brake wiring

[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).

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