Anti-Lock Brake System - 4WAL: Operation

ABS control module receives a wheel speed signal from each wheel sensor. When wheel lock-up is about to occur, the ABS control module activates 3 solenoid valves to modulate hydraulic pressure to each wheel. A pump/motor provides constant hydraulic pressure to the system. The ABS incorporates self-diagnostic capabilities and can store Diagnostic Trouble Codes (DTCs) in the ABS control module.

Two warning lights (Amber ABS and Red BRAKE) alert driver of problems in braking system. Red BRAKE warning light monitors master cylinder fluid level and parking brake lever status. Amber ABS warning light alerts driver of problems in ABS/TCS.

4WD models are equipped with an acceleration sensor. When vehicle is driven in 4WD mode, all 4 wheels are mechanically linked and a situation could arise in which one wheel locks up and causes all 4 wheels to lock up and skid. In this situation, wheel speed sensors would indicate vehicle speed as zero. Acceleration sensor detects and signals ABS control module if vehicle is moving or not. Without acceleration sensor, ABS control module would have no data to compare and would react as if vehicle were stopped when vehicle is actually moving.