ABS Pump
Failing ABS pumps can have different symptoms. Generally if you notice changes in the response of the braking pedal there could be an issue with the pump.
Brake pedal unresponsive
The brake pedal doesn't respond to pressure in the same way as it did, it doesn't depress or return in the same way and feels like it's not properly connected to the brakes anymore.
ABS warning light shows on dashboard
The ABS (Antilock braking system) warning light has appeared on the dashboard and stays illuminated while driving.
Car skids and brakes lock up when braking hard
When pressing the brakes hard in an emergency stop situation the wheels lock up and the car skids along rather than stop quickly in a straight line.
Brakes making a clicking sound
When you apply pressure to the brake pedal there is a clicking or tapping sound. The sound can be loud or quiet and usually won't be felt through the pedal itself. It will usually sound like it's coming from one of the corners of the car. The clicking will usually increase or decrease in frequency with the speed of the car, ie it will click aster at higher speeds.
If your ABS pump needs replacing then whatever happens there's going to be a fairly decent cost involved.
Before you book the work in though there are some companies out there who offer amazing value repair services on these parts, so make sure you search for repairers who can fix the ABS pump for your make and model, you could save a small fortune and get the part repaired and warrantied.