BMW R1200RT/R1250RT Forum

Think you can discount the internal light.  On mine it would only work with the ignition on.

RTman10 wrote: Think you can discount the internal light. On mine it would only work with the ignition on.

Seems to be a mystery wire but it is permanently live even after several days with the ignition of it is still live!

futterweasel wrote:Still wondering what the live pin in the round plug is for [see post one] any ideas?

Reading this thread from BMWLT, http://www.bmwlt.com/forums/rt-series/1 ... igger.html,
it looks like your original thought about the live pin could well be a supply to the Top Case Interior Light.

"I just checked all the wires in the big round plug going to the top box on my central locking 14 RTW.
One wire has power even with ignition off (I suspect it is to the interior light).
Another wire is 0V with ignition off and 7V with ignition on and 12V with brake applied.
All others record no voltage."

"Yes, the one that has constant power is the red wire which is to the interior LED light."

Bet it's for central locking


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15 A (Slot 1: Instrument cluster, alarm system (DWA),  ignition lock, diagnostic socket, topcase light)

(See page 153 of the Rider's Manual).

If the 15A Fuse is removed, the Power supply to the Top Case Light should go off.

Just checked pin voltage in the top box connector ignition on kill switch off, pin1 4.5v/ pin2 12v when brake leaver applied/ pin3 12v continuous/ pin4 and 5 briefly show 10v when central locking button pressed so I guess pin three is not the central locking. Will try again tomorrow with the 15a fuse removed and see if any voltage in pin three if not guess it is for the topbox light, I assume the central locking is not fused but controlled by canbus. Ah the joys of electrickery. Just found mistake in riders manual page 144 picture 1 states No1 is negative terminal next picture states No1 is positive terminal [same terminal] can't trust the manual.

Out of interest, does the small BMW 28 litre Top Case have an internal light.

RTman10 wrote:Think you can discount the internal light. On mine it would only work with the ignition on.

Which Bike & Top Case was this set up on.

On 2 Ks. A1600GTL and an Exclusive.  Both had everything fitted in the top box but turn off the ignition and when the canbus went off so did the light. Was never a problem as Im not allowed out after dark.


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:kacsint2: Hi, just removed the 15 amp fuse and power to the third pin drained to zero so I guess it must be for the topbox light, mystery solved.

I've just had a look at mine. Ignition off, top box open the light stayed on for 5 minutes before I got bored.

Ignition off, close top box and the light goes off, comes back on as soon as you press the release button and open the latch (stuck an iPhone in the box and recorded a video!).

futterweasel wrote:Hi, just removed the 15 amp fuse and power to the third pin drained to zero so I guess it must be for the topbox light, mystery solved.

Excellent, thanks for the feedback.

Nice one, and you found a use for a smart phone

Obviously changed from the 1600 setup.