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: Description
Saab Mark IV Anti-Lock Brake System (ABS) has 3 main components: 4 wheel sensors, hydraulic unit (including valve block assembly) and an Electronic Control Unit (ECU). System is a dual-circuit, 4-port, braking system.
Signals from 4 wheel sensors are sent to ECU, which continuously monitors speed, acceleration and deceleration of wheels, road speed, and tire slip. If wheel is about to lock up, ECU sends signals to solenoid valves for wheel concerned, modulating pressure in brake circuit to provide optimum braking.
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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.