Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Anti-Lock Brake System - Gasoline: Description
The Kelsey-Hayes 4-Wheel Anti-Lock (4WAL) brake system is used to prevent wheel lock-up during heavy braking. This allows driver to maintain steering control while stopping vehicle in shortest distance possible. The system consists of Brake Pressure Modulator Valve (BPMV) or Electro-Hydraulic Control Unit (EHCU), Vehicle Speed Sensor (VSS), VSS buffer, wheel sensors, warning lights, electrical wiring and hydraulic lines.
The BPMV consists of an Electronic Control Unit (ECU), hydraulic control unit, 2 accumulators, pump motor, and relay. The hydraulic control unit consists of an isolation solenoid valve, Pulse-Width Modulated (PWM) valve, a High Pressure Accumulator (HPA), Low Pressure Accumulator (LPA) and a reset switch on each channel. If overhaul or repair to any component on the BPMV is necessary, replace complete assembly.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.