1988 Pontiac Bonneville Driver Info Window

Hello, I have a Pontiac Bonneville 1988 SSE in very good conditions, a wile back the driver info window turned off and from time to time comes back on, every time I press the break it goes off or the light decreases dramatically, when the brake its released again, the light comes back on with intensity, but form time to time goes of for no reason, I took it to a very dishonest dealer and say that the car its so old that the dash board inside its falling apart, but as a fact I know that's not the case because I open it once and it looks brand new, what can be the problem?