If the bulb is definitely good, then check the fuse. You'll probably need the handbook to locate the fusebox and to identify which fuse runs to the reversing light. Pull the fuse out with pliers or tweezers and see if the wire is broken. It's probably OK, which means that the fault lies with the switch on the gearbox which activates the light when you put the lever in reverse.
See http://www.howtomendit.com/answers.php?id=117115
Sven Ellis
January 2009
Also if any knows why my reverse light still won't work even thought I have just put a new bulb in ????
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