Topic: Resistor for my LED Brake light?

[Duke4Life]

Hi guys, first week on the SOHC forum. My project bike is a 1973 CB750K. I've been struggling a little bit with my wiring. I've managed to wire up the new Tach and Speedo and my rear blinkers and tail lights have power but I can't get the tail light to light up when the brake is engaged. I know I need resistors for the blinkers. They are ordered and on the way, but DO I NEED A RESISTOR FOR THE LED BRAKE/TAIL LIGHT?? If so, can i use the same as the blinkers and how is that resistor wired to the brake light? Thanks in advance for the help.

Also, sorry if there's another post with this question. I searched the site but didn't find anything.

[Bodi]

The resistors used for signal are generally to fool a stock flasher relay into thinking they're normal bulbs, so it will flash. Swapping in a modern electronic flasher relay avoids any need for the resistors.
Assuming you are using plug-in LED replacement lamps, no resistor is needed to light them up on the 12VDC bike power.
Check your tail and brake light with a normal lamp.
If it works, check the LED lamp in something else - many older cars use the same type of tail lamp and you can swap in the LED unit and try it for both marker and stop functions.
If the tail/stop light works with the normal lamp and the LED lamp is good...
I don't believe there is any way the tail light socket polarity could be reversed - but LEDs only work when wired the "right" way.

[Duke4Life]

Thanks for the input. The break light I'm working with is a stand alone unit and not just an Led bulb placed inside the stock lighy. I've checked the light and it does have 2 intensities. I was thinking that it might be the brake switch. I wanted to ask the question about the resistor before I just went and bought a new switch since it looks rather new. The bike was bought with no brake light. This may be a really dumb question but if it was a rear brake switch problem wouldn't it still work with the hand brake? Please. Forgive me. Its my first bike and I'm definitely doing this build solo. 

[Duke4Life]

Calj,
Great advice.  I'll grab the stock light and check the switches.  If they work I'll wire up the resistor when they come in for the blinkers. Thanks for the advice. Love this forum.

[cougar]

No resistors needed in/on brake light. They're only needed for turn signals to make the circuit draw enough power to make a mechanical blinker relay work properly. Possible causes are faulty brake light switch (front and or rear come on if neither make the light come on) , faulty wiring to or from switch, blown fuse, improper or no ground. I've been running LED in my rear brake light for a couple of years with stock wiring and no resistor with no problems. Keep digging and asking you'll get it.   ...cougar..

[Jay Ace]

^ Still need to get back to you, cougar ... Sorry, been busy.

Like others have said you should not need anything for the brake light. Did you try measuring at the connectors to see if you are even getting power back there?
If not, follow the wires backward and see where the break is.

Also, if you don't want to fool around with resistors, you can get this thing and call it a day. I've tried several other ones that people have suggested and none of them worked. The one I got, I had to reverse the polarity at the flasher to make it work but other than that it works perfectly.

[Duke McDukiedook]

Check your ground and connections if it still does not work.