2005 R1200RT turnsignals miraculously started working

I don't think this is model specific, but it might be. It is specific to the CAN-BUS electric system.

I had a problem with my turn signals not working after an all day ride in the pouring rain. Initially the right turn signal would not turn off and then stopped working and then the left turnsignal wouldn't come on. (while I was riding in the rain storm.) The four-way flasher button worked and all four turn signals flashed. But they did not work with the left and right turn signal buttons. Even weeks after the rainstorm, the turn signals did not work.

After several weeks of trying to dry the signal button out, spray WD-40 etc. I took the bike to the BMW dealer to get diagnosed. They found the left turn signal started working after they connected the diagnostic computer. (It didn't work on the left turn into the dealership.). So I left the dealer with them ordering a right turn signal switch. Within 2 miles, the right turn signal started working. And both have been working consistently for 1,000 plus miles and many months.

So just a post to suggest before you purchase a new switch, take the bike to your dealer and have them put it on their diagnostic computer. I think that was the "magic" that got both of them working.

YMMV, Tim

My 2000 R1100RT has the same problem. Very unpredictable but always involves high humidity or rain, and will usually correct itself after a dry period. I think it is the input circuitry of the IC that controls the flashers. On my RT, the individual inputs have to be grounded by the switch to perform their function. Each input is permanently connected to the +12 with a resistor inside he IC, and since the turn signal IC has several inputs, the total quiescent drain from the battery becomes marginally significant. My theory is the resistor is deliberately made as high as reasonable to minimize the overall quiescent drain, but maybe they should have used a lower value of resistor in the IC which would cause more quiescent 12 V drain, but then wouldn't be so sensitive to water in the open switches and wiring.

My theory at least - YMMV.