Control Module And Hydraulic Unit
Control module
The brake control module (BCM) is mounted on the hydraulic unit in the engine compartment behind the battery toward the cowl panel. In the event of a fault in the brake control module (BCM) or hydraulic unit, they are replaced as a single unit. The control module contains two different microprocessors that receive signals from the different sensors in the system. The microprocessors work in parallel following a program that calculates how the various functions should be regulated.
The control module has twelve valve coils for hydraulic valves, of which four valve coils are for outlet, four are for intake and four are for stability and traction control. Some valve coils that are used when pressurizing the brake system are regulated via analog control, enabling the valves to be controlled linearly.
The control module contains an internal pressure sensor that measures brake pressure in the system. The control module is supplies power via three fuses and is grounded in two grounding points.
Control module software and the valve coils of the hydraulic unit are capable of being diagnosed.
Upon replacement of the brake control module (BCM), the system must be calibrated following the information in VIDA (Volvo scan tool) vehicle communication or manually as determined by the test drive.
Hydraulic unit
The hydraulic unit is mounted with the brake control module (BCM) as a unit and is located in the engine compartment behind the battery toward the cowl panel. The hydraulic unit consists of:
- a pump motor
- hydraulic valves
- check valves
- an integrated brake pressure sensor.
The pump motor builds up the brake pressure necessary during ABS, traction and stability control. The pump motor also generates a reduction in pressure on the return side of the system, that is to say it returns the hydraulic fluid to the brake cylinder.
The pump motor and the internal pressure sensor are capable of being diagnosed.