I could drive for about 30 -40 minutes without a problem, then withoy warning the brakes will not hold. I would have to exert a lot pressure on the brake pedal. I then have to keep a far enough to safely stop the car. This would happen several times until I got home safely.
What would it cost to rebuild the ABS system and install? on 1992 Mercury Cougar
The brake system needs to be inspected to see what component or components have failed. If the ABS light is on the ABS system may have a fault but if the brake pedal sinks to the floor when the brakes are applied or you have to "pump" the pedal in order to stop or are loosing brake fluid the master cylinder has failed or the system has a leak that needs to be repaired. If the brake pedal becomes rock hard and requires a lot of effort to stop the car the brake booster may have failed, it receives vacuum from the engine to assist you when braking to decrease pedal effort when it is working properly.