Return pump, TCS function
The return pump is utilized in different ways, depending on whether the TC/ABS control module is working in ABS mode or TCS mode. The function of the pump when the control module is in TCS mode will be described here.
The return pump is continuously active during TCS modulation with braking.
Pressure is built up by closing the pressure relief 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 relief valves closed (to maintain pressure) and opens the pressure relief valve to reduce the pressure. The surplus brake fluid resulting from opening the pressure relief valve is returned to the master cylinder.
The return pump is described more fully in .