6.3. Electric system
The Bosch 5.0 system has very simple and compact design that increases its reliability. The quantity of external components is minimized. From their number there were only wheel sensors, an alarm lamp of the ABS system and the switch of a stoplight.
Lobbies and back wheel sensors serve for measurement of speed of wheels. On the basis of their signals the module of management of the ABS system defines whether any wheel shows a tendency to blocking.
The alarm lamp of the ABS system warns the driver that because of malfunction of system there was its automatic shutdown. However the brake system continues to function normally.
The switch of a stoplight informs the module of management on braking. It allows the module of management to control parameters of rotation of wheels more precisely.
The diagnostic socket serves for connection of Volvo System Tester when performing diagnostics.
If the car is equipped with the DSA system (system of dynamic stabilization), then the module of management of the DSA system obtains data on the frequency of rotation of wheels which are necessary for measurement revolving. The module of management of the DSA system obtains this information from the module of management of the ABS system. For this purpose three lines of communication serve. The DSA system
does not use a brake for control revolving.
Internal relays (for the pump and valves) have the separate connections protected by fuses.
At inclusion of ignition the system checks the electric resistance of all components. During this check the alarm lamp burns. After completion of check (4 c) the lamp has to go out.
At the movement of the car check of the electric motor of the pump (and by that — the relay) is carried out at a speed of 6 km/h. Also inlet and final valves are involved. At a speed of 40 km/h check of operation of wheel sensors is carried out. In operating time of the ABS system the pump functions in the continuous mode.
Valves regulate pressure in wheel brake cylinders.