I have a 1991 Chevy S-10 Blazer (4.3L, 4x4) in which the instrument panel lights for the Parking Brake and the Anti-Lock Braking system will not go out when the car is started. I checked the parking brake cable attached to the foot pedal to see if it was broken or disconnected but it is not. I checked the master cylinder but the fluid level is full. Brakes seem normal while driving. Any suggestions on what may be causing this or what else to try?