The anti-lock system found on 1992-95 is a sophisticated electronic and hydraulic system. Sensors at each wheel generate a signal relative to the speed of that wheel; the signal is transmitted to a computer which compares the rolling speed of each wheel. If one (or more) wheels begin to slow out of proportion to the others (as would happen if one began to lock under braking), the computer signals the ABS hydraulic unit to reduce brake pressure to that wheel.
Braking effort is reduced and the wheel is allowed to roll until it approaches the same speed as the others. Stability is thus improved by eliminating wheel lock. Because of the complexity of the system, pressure changes can occur several time per second in a panic stop as the system reacts to varying signals from all four wheels.
Should any part of the ABS system fail, an indicator light on the dash will illuminate; this DOES NOT indicate total brake failure, but only a loss of anti-lock function. The brake system will still function as a normal, non-ABS system.
Models equipped with this system may exhibit various behaviors which are not seen on normal brake systems. A pulsing, felt in the brake pedal or steering, may be noticed when the system is activated by hard braking, particularly on slippery surfaces. Although surprising, this pulsing is normal and a sign that the system is reacting to conditions. Additionally, as the vehicle reaches about 4 miles per hour after starting the engine, a whining or motor whirr may be heard in the engine compartment. This is from the system performing a self-check and building pressure; again, quite normal.
As complicated as an ABS system is, it rarely fails. Extensive development has made the system reliable and long lived. Troubleshooting and diagnosing an ABS system requires test equipment for both the electrical and computer portion as well as sophisticated hydraulic test equipment. It is a job best left to those well-trained in the field.