The ABS Pump Modulator Combined plays the same role as a separate pump and modulator does in your car's ABS system and tends to be used in newer vehicles.

ABS Pump Modulator Combined works with the ABS Control Unit ECU to control your car's braking system.

ABS Pump Modulator Combined is part of an important process which essentially allows you to maintain control of steering, enabling you to brake with ease by regulating the air pressure in the wheel brakes. The ABS Pump Modulator Combined plays its part in this process by receiving messages from the ABS Control Unit ECU, when a wheel is likely to lock and skid, and it adjusts the air pressure in the brake chamber to stop this from happening.  The pump then ensures this pressure is pumped back up again. 

If there is a fault with your ABS Pump Modulator Combined the warning light will show on the dashboard, perhaps having shown intermittently before, and the ABS system will disable itself. The Check Engine Light may also show and your speedometer could stop working. A faulty ABS Pump Modulator Combined may affect braking when driving slowly. Electrical issues; faulty pump motor, faulty fuses, sensor and connector issues caused by water erosion could be the reason your ABS Pump Modulator Combined has stopped working and needs replacing.