[Sid Squid]

Does everything else electrical work properly? If no check fuses. If yes, pull the wires off the front switch and short them, does the brake light come on? If yes, then both switches are duffed*, if no, then make sure there's a live at both switch connections. If yes, check the rear light connector under the pillion seat - typically it's cable tied to the left frame rail, it's a white three pin connector. Do all three wires seem OK? Check along the wire from the connector to the light unit, any damage? At the loom side of the connector check that one wire is neutral, one is live all the time the ignition is on, (back light), and one comes live when either brake is pulled, if that's the case then the rear light or wire thereof is faulty.


*Believe me, it's rather more common than you might think. Obviously it's most unlikely that they'd fail at the same time, but one failing often goes unnoticed - if one works the light comes on and no one runs in to the back of you, often it's only when the second fails that it becomes apparent.