Originally Posted by slartidbartfast
None of the other responders have thought to mention that the 1150GS doesn't have a "Check Engine" light.
Maybe your alternator belt is loose so it slips when wet and the charge light is coming on? Which light is it exactly?
I'll bet it is the red exclamation point light beneath the break light on the gauges. If so, that too is a break failure indicator light, no?