How to connect aux brake lights to canbus wiring

[Quaestrix_BMW]

I have a 2010 model GS and bought a Givi E55 Maxia de luxe top box with LED brake light kit, does any know how to connect the 2 wires from the Givi brake lights to the CanBus wiring system of the bike?

I want to avoid aspected problems with the CanBus system and PWM signal.

regards, Ed

[RCH]

In the canbus system the the tail light gets 6vdc, when you apply the brake the canbus sends 12vdc to make it brighter. There are two wires and a ground, what I did was tap into the existing tail/brake light system. It won't hurt if you test to see which lead is correct.

That is how I did it on mine and my wife's motorcycle, they work fine. If you are using an LED auxilary light you should be fine as the canbus is set for a certain number of watts, but you should be under that limit.

[marc]

Originally Posted by RCH

In the canbus system the the tail light gets 6vdc, when you apply the brake the canbus sends 12vdc to make it brighter.

That is not quite correct. First, not all CAN bus bikes use the same scheme. Second, the scheme used is called pulse width modulation. The effective voltage may be on the order of 6 and 12 volts (don't know the actual numbers) but the the actual voltage is always the 12-14 volts that is standard for your bike. The 12-14 volts is modulated on and off to give you the lower effective voltage. You'd need an oscilloscope to see this.

[RCH]

What I wrote came right from the BMW dealer, as far as how it works.

I asked before a bought the LED lights, made the brackets, and installed them. It may not be as technical a discription, but I'm not an electrician, but I know what I did works with no fault codes.

I put the same thing on a friends 1200 as well.
With brake light on

[RCH]

With tail light on.
Both lights are on, but, looking at it with a camera both lights seem to pulsate, but just looking at it
with the naked eye they do not.


I bought the light at an online 4WD Jeep store and made the bracket.
I bought my wife's at an online big rig store and made a bracket for her's as well. they both work fine.

[RCH]

Marc, after thinking about it for awhile I have to agree that not all canbus systems are the same. The Pre-LED GS would be quite different and I cannot disagree with you.

On the other hand I believe the 2010 that is in question here would be very easy to wire a second light.

[pdxrmccgs]

PWM is a on chip digital method of varying voltage over hard
wire. The signal carries no intelligence other than the decrease/increase
of voltage that the load sees.

CAN is a on chip serial digital protocol (several exist) that carries info/intelligence on 1 or 2 twisted wires around the "network" or "bus". The info is contained in "data frames" or "packets" as the
following link explains:

CAN bus Data Frame

From the GS wiring diagrams it appears that the only real CAN
communication is between the engine computer (BMS-K) and the
body computer (ZFE)

If you want to scratch your embedded chip engineer itch:

http://microcontroller.com/learn-emb...ie/CAN1big.htm

[marc]

Originally Posted by pdxrmccgs

From the GS wiring diagrams it appears that the only real CAN
communication is between the engine computer (BMS-K) and the
body computer (ZFE)

And the COMBI (Instrument Panel Controller). The optional ABS controller, Alarm module, and tire pressure modules are also attached to the CAN bus. As you noted Lights, switches, and sensors are direct connected to one of the various controllers and have nothing to do with the CAN bus.

[t6pilot]

I wired P3 lights to my 2011 GS followed the on line instructions for the correct wires to tap into worked super should be the same for your lights

[GeoJeff]

Originally Posted by Quaestrix_BMW

I have a 2010 model GS and bought a Givi E55 Maxia de luxe top box with LED brake light kit, does any know how to connect the 2 wires from the Givi brake lights to the CanBus wiring system of the bike?

I want to avoid aspected problems with the CanBus system and PWM signal.

regards, Ed

I just did this yesterday on my 09 GSA, for the brake light (2-wire) kit for my SHAD SH48 topcase.
I just tapped into the ground (brown) and brake (gray/black) wires of the tail light using easy-tap connectors. Works perfectly. FYI, I also tried to see if I could use the lights as running lights as well by tapping into the tail light wire, but the lights also came on full intensity (like brake), so I removed that connection.
On a side note, I came across some nice-looking splice connectors on the web (link below), which look better than the one I used - might get some to have on hand...
Posi-Tap- No Crimp Tap
Anyway I really like the extra high-position brake lighting. Good safety feature I think.