Hot Rods Help--Third Brake Light

I want to put a third brake light on my 31Model A and I want to mount it temporarily in my trailer hitch mount and wire it into a 4 prong plug so that I can remove it and hook up the trailer. How do I wire it in that only the brake lights work and not the signal lights. Thanks in advance for any help you can give me. Dale

 

You need to come off the brake light switch, the same place that the turn signal switch is fed from. If you are using the stock Model A switch, it is the green wire.

 

Two choices; bring a wire directly from the brake light switch, or use diodes in each wire from the brake/turn lights. You'll need two diodes rated for 5 amps each. Using diodes will allow you to use the wiring from your trailer plug. Connect the ground normally, then connect each brake/turn light wire to the third brake light with the diode installed in-line in each wire.

 

thanks for the help guys, will run a wire from the brake switch to a plug in the rear and make a new pig tale to plug into the third brake light.

 

Trailer hitch on Model A? I would like to see how you did that. Have been thinking about finding some old trailer to pull with my roadster and put my bobber motorcycle on it.

 

So, what if you are simply changing lanes and not depressing the brake pedal? The third brake light will blink with the signal that is flashing, diode or no diode! You need a circuit that will separate the brake from the turn signals. It can be done with some discrete components, but not 2 diodes! Been there done that!

 

I think that we are way overthinking this, if the third light is wired to the brake light circuit it will work as a brake light just like your regular brake lights do, just pull a wire from the brake light circuit and put a quick connect in it plug the third light in when in use and unplug it when not in use.

Sometimes I just don't get the HAMB, KISS baby.

 

Yep, it will.... But if the object is being seen, having this light blink also will draw the eye and improve the chances that they'll see the signal light.

 

Mine isnt a model A, but I just bought a random hitch at a yard sale and fabbed up mounts to adapt it to my frame.

 

Exactly what I was going to say. I just put a five dollar brake light into the trailer hitch on my wife's 2014 Ford flex. Two wires coming off the light plugging into the four wire trailer hitch prong. Bada bing, comes on when she hits the brakes.

 

Hey, how about a pic of the trailer hitch on the Model A???

 

So does it blink with right or left turn? LOL