Another item you may wish to check is the battery. A number of years ago a weak battery in my 201 was causing the SRS light to illuminate. When I put in a new battery the issue never re-surfaced. It is unusual, though, that it is coming on as soon as you press the brake pedal. Gilly makes a good point that it seems to be acting like the lamp failure indicator. Anyway, I just thought I'd throw the battery idea out there.