On the 2000 bikes , you usually have to have the dealer reset the light. It will also reset on it's own after 50 start and run cycles of at least 30 seconds each. If the light is lit and stays lit when you run, it is a current code for a fault that exists now. If it comes on at start up and goes out and then back on again, that is a historic code of something that happned in the past.
Here's a way to check the code for why the light is lit.
http://www.hdtimeline.com/general_tips/729-00_03_hd_codes_and_activation.html