Well, I am sure you will be getting more detailed responses, but it could be a number of things. My assumption is that all other electrics are functioning OK??? A key question to find the answer to is "are the brake lights working??" If the brake lights are not working (and even if they are, actually) the problem might be the big flasher relay unit that is mounted on the driver side inner fender panel (below, behind and under the brake/clutch fluid reservoir). This is an expensive unit to replace, but it is repairable. In my case it turned out that cleaning up the points with fine emory paper did the trick. There is a trouble shooting guide in Norm Nock's treatise and also I believe in the factory workshop manual. Of course, it could just be the little flasher relay, too. Good luck.