2011 R1200 RT Auxiliary Brake / Tail Light

[PapaCall]

I just finished installing a Whellen Series 400 light on my 2011 R1200RT.I tried using a relay with a trigger wire running from the hot side of bmw brake/tail light and it worked without any fault. The problem is the relay vibrates and has a continues buzz. I unhooked everything and started over. Tried a different relay, same thing (yes I had the relay wired properly). Unhooked everything again this time I taped onto stock light with hot and ground and it works perfect. I don't get a yellow triangle,am I good to go? I am told by whelen that the light only draws 1.5 amps. This is one awsome light with 72 leds. Am I going to burn up anything on the canbus system? Thanks for any HELP PapaCall

[dirtrider]

Evening PapaCall

 

You are treading on very thin ice there. I have my doubts that relay will work long into the future without causing you issues.

 

 

Problem is your tail light & brake light use the same wire & basically the same circuit. The computer pulses the brake light at a modulated interval (ends up around 8 volts) then when the brake light comes on the computer just increases that voltage to 12+ steady DC volts.

 

That relay vibrating you were getting was caused by that pulsed 8 volts going to the tail light acting on the relay pull-in coil.

 

Bet you it is still vibrating inside the relay you just can't hear or feel it.

 

Maybe it will work for a while & maybe it will cause you some issues down the road. You won't know it has issues until it does.

 

 

[PapaCall]

Iam not using a relay in this application, just wired the new light in conjuction with the stock light, a ground and hot wire tap off of stock light

[dirtrider]

Evening PapaCall

 

 

Yes, that's probably your best bet (that wasn't clear in your first post).

 

In any case you have added around 20 watts give or take to the tail light circuit so time will tell if it causes you any issues.

 

As long as the yellow dash warning light isn't on that is a good sign.

 

As far as harming the CanBus that won't happen as the CanBus doesn't operated that rear light (CanBus is only the buss used for the onboard computers to talk with each other).

 

It is definitely placing more load on the electronics in the computer that operate that rear light.

 

On it causing long term computer driver damage I really can't say but that is a possibility. If I had to guess it would be you won't have problems but you are definitely operating outside the designed load design of that rear light system.

 

If it were my bike I would try to find some LED's to replace the stock rear tail light bulbs (or at least one rear bulb) as that would probably remove more than the extra load you have just added to the circuit.

 

[PapaCall]

Hello DR,

Thanks for the info It has been most helpful.

PapaCall