Should you pump the brakes when driving an ABS-equipped combination vehicle?

On ABS-equipped vehicles, do not pump the brakes. Apply firm, steady pressure and let the ABS system modulate brake pressure automatically (dozens of times per second) to prevent wheel lockup. Pumping defeats the ABS and reduces braking effectiveness. The vehicle may feel and sound different during ABS-active braking — pulsation in the pedal, mechanical noise — but this is normal operation, not malfunction. Old habits from non-ABS vehicles (pumping, stab braking) actively work against ABS. The exception is a true brake failure where pumping is a last resort to recover hydraulic pressure, but this does not apply to air brake systems and is not normal operating practice on ABS systems.