[GuyO]

Oops, forgot to add that to make the light go out you must re-center the proportioning valve. Known as "centering": either jam the brakes really hard or push in the pin that is covered under a rubber protector on the valve. With the pin depressed it will allow fluid to go to both front and back systems. This will equalize the brakes. At least you know you don't have a problem in the warning circuit! G.