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trailer wire r 1200 rt

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c-more

Need help.

I have a 2006 R 1200 RT I’m wiring up a trailer plug. I have been reading different forums and because the 1200 has the CAN-bus wiring loom I purchased a trailer isolator relay set up form a US company (electrical connection) I’ve followed the instructions, but when the ignition is switched on the one of the relays chatters until I pull the brakes on and the chattering stops. I have also put in a fuse panel (eastern beaver) so as not to draw any power from the bikes wiring loom.

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dirtrider

Morning C-more

 

I didn't think electrical connection made a specific isolator kit for the 2006 era (C.A.N.) equipped BMW's.

 

In any case-- your relay is probably buzzing as your BMW 1200RT has a pulse modulated tail light that doesn't come on to full voltage until the brake light comes on. If you have that (buzzing) relay wired into the tail/brake light circuit it will be difficult to keep it from buzzing. This has nothing to do with the CanBus part of the bike as it is a function of how the brake/tail light operates.

 

SO, my suggestion is to call "electrical connection" & see what they have to say about your issue. Maybe they have a work-around for BMW 1200RT pulsed tail light systems.

 

If it turns out they still don't furnish a compatible isolator unit for your BMW 1200RT you can simply use a pressure activated brake light switch in your rear brake circuit (older Fords used that type of brake pressure switch). Just use the brake pressure switch to run 12 volts to your trailer brake lights when your rear brake pressure increases. This will take some brake system re-plumbing to add that switch & hydraulic Tee.

 

Another way if you search around-- There are also some small pressure activated custom brake light switches available that are used for custom built motorcycles that just use a longer banjo bolt for brake hose attachment to the caliper. These banjo bolts have a built in switch that completes a circuit when they see braking pressure.

 

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c-more

Thanks for the information DR,

I’ll try and call them tonight my time, and see if they have run into this problem..or if there is an electrical way around the issue, as even if i disconnect the power to the isolator and turn on the ignition switch there is still a buzzing happening so as you say it’s the function of the brake/tail light.

 

Bruce

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c-more

Hi Ron,

thanks, this is what i have on the bike now. at the moment i have disconnected the tail/brake light connection turned on the power to the bike and the chattering stops, as DR said the BMW 1200RT has a pulse modulated tail light that doesn't come on to full voltage until the brake light comes on. I’m going to get up early Tuesday morning and try and call the US from Australia once I work out the time difference, and see if the guys can help around the issue,

 

Bruce

 

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Buckster

Bruce, I too tow a trailer (small cargo) and have researched the tail/brake wiring issue. Please review this previous post Pulsed tail light thread While I originally refer to this as Can-Bus wiring, this is not technically correct. Can-Bus is not the wiring medium that controls the tail/brake wiring. That is controlled by the ZFE (body) computer. Can-Bus is only the wiring medium between the various computers and instrument panel.

I have recently come across a new solution in the Curt 56201 Stop/Tail/Turn converter (about $85) which has been developed for BMW cars (also using pulsed tail/brake wiring) that are used to tow. This converter will work for a trailer that has combined brake/turn signals but not I have not found a pulsed tail/brake converter that will work with a trailer that has separate turn signals ( which my trailer has). I should send an e-mail to Curt and see if they have a solution.

If you're electronically inclined, Wire 2 wire has a great project to build your own PIC controlled STT converter for about $40 if you already have a PIC programmer.

I think that Dirt Rider's solution is a very viable and simple option and I may use it, using the rear power outlet to supply 12 volts + for both the tail lights and brake lights (via the pressure switch). Dirt Rider's suggestion also works because if you tap into the rear brake line at the caliper, the light will activate with either front or rear brake application as the front brake activate the rear caliper too. Dirt Rider, thanks for the suggestion.

Buckster

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Alfred02

I understand what has been done in the Pulse thread, but if all that has been done is add a relay that picks up the pulsed voltage to turn on the tail light using battery voltage across the relay and the relay shatters, then all you need is a small size capacitor across he coil, which will supply to the coil during the "OFF" period.

 

I would start with a 220uf electrolytic capacitor and go bigger if this doesn't work.

 

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Dave Glen

G'day blokes, you are all making it too complicated, follow the KISS principal. I have towed a trailer for thousands of kilometres and to get around the potential stop/tail lights trouble with the RT electricals I have fitted LED lights. Thats all. The wide voltage requirements of the LED's mean that when on tail light it is about half as bright as when on stop. The added gain is the dash warning light isn't activated.

Try it!

 

dave THE bastard

Australia

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kellenbenz

Dave ....can you give us the led bulb source or part number that you used.....maybe a picture if you have one?

 

Ron

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Buckster

Alfred02, how does the relay differentiate between the tail and brake functions? There is only 1 output of the relay.

Buckster

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Alfred02

Buckster

As I admitted that I hadn't looked into it deeply as I don't use a trailer.

Nevertheless, having a quick look at my User manual shows that there are two bulbs. One for tail light and one for brake light.

So it should have "two" relays.

Now any normal trailer lights that you buy, always have two separate bulbs in their trailer lights.

From my understanding, the user just wants to stop the chattering of the relay and for that, the capacitor will do the job.

Your normal standard car/trailer lights use a lower wattage bulb for the tail light and a higher wattage bulb for the brake light.

If his trailer lights are setup the same (conventional), then he would just have to add the capacitor to the tail light relay "only".

The NPN Transistor/check LED's of the other person is more elegant and something I would do if I would drag a trailer, but most people do not have an electronic background and KISS method is better for them.

 

 

 

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dirtrider

Evening Alfred

 

While the 05 1200 RT does indeed have 2 rear bulbs they are wired in parallel & are BOTH fed from one single wire coming from the ZFE module. (don't confuse this with the early 1200GS dual light set up)

 

For the tail light the ZFE pulses that rear bulb circuit to hold a pulsed voltage at the rear bulbs to somewhere around 5-7 volts. Then when brake light required the ZFE goes full voltage (12+ volts) to get the brighter brake lights.

 

While a capacitor could take some of that buzzing out of the trailer control relay keep in mind that relay needs be OFF for proper trailer tail light & go on (only) with the brake light.

 

Even if the relay pulsing is dampened that relay still needs to remain OFF until brake light application so just adding a cap. will leave the pull-in coil at or very near pull in so hitting bumps & vibrations could cause flickering brake lights on the trailer.

 

When I was trying to make an auxiliary rear tail/brake light for my 1200RT I never could get a control relay to keep from buzzing. I added a cap but that only made the relay latch in at brake light apply & not drop out after brake release. (just not enough pull-in/drop-out window in those relays to be useful for brake light control.

 

I fooled with a Zener & some caps as well as a Zener & transistor set up (got it to work but barely). Not reliable enough to operate properly at low idle voltage with all accessories on & heated gear plugged in though.

 

Finally ended up with an LED array using voltage sensitive LED's. That worked no matter what the voltage thresholds & system loading.

 

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Alfred02

Thanks DR

So the correct understanding is that despite that there are 2 bulbs, both are dim for normal tail light and both go bright for Brake light?

 

Now I understand the problem.

It could still be done, but then gets too involved for the average rider out there, so yes I agree.

Voltage sensitive LED's would be the most elegant solution.

 

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Dave Glen

G'day all, I can probably dig up a photo of the trailer but it won't help, basically I replaced all the incandescent globes in the trailer with LED globes sourced from Deal Extreme and Jaycar (our local electronics parts store) and rewired the brake/tail socket to a common from the bike.

 

dave THE bastard

Australia

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kellenbenz

Thanks Dave!

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Bigfish
On 10/19/2012 at 8:02 AM, kellenbenz said:

Dave ....can you give us the led bulb source or part number that you used.....maybe a picture if you have one?

 

Ron

 

IMG_9432.jpg

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