Or bad bulb. Yank the cover of the brakelight and check the filament just as you would a household bulb. If that turns out to be good, the check the wiring. If you have basic knowledge of how to use a multimeter, specifically a voltmeter, set it to AC volt range around 13VAC, and probe the common (typically brown) and brake wire (should be red) and see if you get ~13 with the brake applied. Hope this helps.
YES IT DOES HELP. THE LIGHT IS GOOD AND WORKING ONLY WHEN THE BRAKE IS APPLIED NOTHING CHANGES TO THE LIGHT JUST STAYS LIT AS ALWAYS NO BRIGHTER FROM BRAKE.ILL TEST THESE WIRES TOMORROW AND SEE WHAT COMES UP. IF THOSE READINGS ARE NOT WHAT YOU TOLD ME THEN WHAT WOULD BE FAULTY?TO BE REPLACED
I had 2 ZRs' with bad switches. The switches are by the handlebar brake lever. Look up the parts finder from any Arctic Cat dealer for your sled and look under the hydralic brake control assembly, number 17 I think. Mine was just a short piece that took me 10 minutes to replace once I found it. But, I was able to just change out the switch and not have to change out the wiring harness.