Return pump, ESP and TCS functions
There follows a description of the how the control module operates in ESP and TCS modes. Refer to RETURN PUMP FOR OPERATION IN ABS MODE .
The return pump is continuously active during ESP and TCS braking.
Pressure is built up by closing the pressure reducing valve and opening the pressure increase valve to supply the return pump with brake fluid. The control module closes the pressure increase valve when a preset pressure is reached.
The pressure is then modulated as the control module opens the pressure increase valve to increase the pressure, keeps the pressure increase and pressure reducing valves closed (to maintain pressure) and opens the pressure reducing valve to reduce the pressure. The surplus brake fluid resulting from opening the pressure reducing valve is returned to the master cylinder.