However the fact that you have to use a resistor to make the flash rate work correctly should probably tell you that it is NOT 10W, where no resistor would be necessary. Have you actually measured the current (without the parallel resistor) - a series resistor would be necessary to limit the forward current, but no parallel resistor should be necessary to make the blink rate correct (on a Touring) if indeed is truly expending 10W of electrical power.