If a brakelight bulb fails, the "canbus" electrical circuitry is programmed to use the tail light bulb instead.
This leads a lot of people to change the wrong bulb.
If the bulb you fitted is not of the exactly correct resistance this will also cause your problem.
Always use proper Vauxhall bulbs from your Vx dealer.
The canbus system is very sensitive (many would say over sensitive) and will often claim a bulb has "blown" when it has not but its resistance has moved outwith set parameters.
spud
September 2009