Anti-lock brakes add a hydraulic unit between your master cylinder and the wheels, which raises a common question: do ABS-equipped cars need a special bleeding procedure? The answer is usually no - but sometimes yes. Here is when.
Normal bleeding usually works
For a routine fluid change or a repair that did not let air into the ABS unit itself, ABS cars bleed just like any other car - the standard sequence and method work fine; see brake bleeding basics and the bleeding order. As long as you never let the reservoir run dry, air stays out of the ABS module and a normal bleed gets a firm pedal.
When the ABS unit traps air
The special case is when air gets INTO the ABS modulator - for example after the unit was opened, the system ran completely dry, or a component in that circuit was replaced. That trapped air will not come out with a normal bleed because the fluid passages are closed until the pump and valves cycle - see spongy pedal after bleeding.
The scan-tool bleed
To clear air from the ABS unit, a scan tool commands the ABS pump and solenoids to cycle while you bleed, opening the internal passages so the air can escape. This is the manufacturer-specific automated bleed procedure. Without it, a car with air in the ABS unit keeps a stubbornly soft pedal no matter how much you bleed manually.
Practical takeaway
Doing a normal fluid flush or pad job? A standard bleed is fine. Opened the ABS unit or ran it dry, and the pedal stays soft after a thorough bleed? You likely need the scan-tool procedure. Either way, keep the reservoir topped up, use fresh fluid, and maintain quality pads and hardware.