BMW R1200RT/R1250RT Forum

Hi everyone, I have not been on the site for quite some time, been out busy riding and enjoying my RT.
I happened on an idea after talking to a BMW dealer regarding the accessory spotlights, after having a small dizzy spell when told the price of the complete kit and fitting, I of course had to participate in a couple of ales to digests the information. Once I had participated  in that recreational  enjoyment, came to the conclusion maybe I could beat the system!, firstly I brought to which I consider adequate spotlights from China, and purchased  the wiring loom and switchgear from BMW. So here's a question, thinking that the switchgear would be simple and it will consist of  a wiring loom with two terminals each for the spotlights one either side,  and  the plug for the switch on the handlebars, but!!!, where the wires go down to  each spotlight  no such luck as a switched live and neutral from the handlebar control; there is 4 wires, two I have meted out with metre  and live 12.5v, and two are showing 11.2v.
Putting my lights on the 12 V feed in that multi-plug socket they come on which is good, but the switch on the handlebar cluster  is made redundant.
So why have four wires when two will be okay, and why have a permanent live going into the spotlights what are the other two was for?.
Can anyone help. Many thanks in anticipation. Tim P/s it is a keyless ride model and when you turn off the ignition, you lose the 12 V supply to the plugs.

Well - the small button has a microprocessor inside - talking to the main unit.
The main unit sends a command to the lights - that also has a microprocessor inside to switch off - on etc etc.
The lights are talking to the bikes main computer - telling a lot of stories :-) .  - ToHot - Not working, lo voltage  etc :-)


The main processor do also send out a broadcast when bikes is switched on - asking what extra systems are mounted on this bike - and the lights++ are shouting back - I'm here :-)

Thanks STeinar for that explanation, it does leave me wondering what the advantage is for the owner. It occurs to me that it just means when anything goes awry the bike has to return to the mothership, BMW, for expensive attention. I'm old enough to remember the dreadful electrics on British bikes and the ultra reliable and comprehensive electric on Japanese bikes, my first being a completely reliable Honda C50. Not sure this is progress, would not like to face an electrical problem on a GS in the middle of nowhere.

just wire them direct to the battery via a 12v relay that is powered by an ignition controlled live