FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
Courtesy of Operation CHARM: Car repair manuals for everyone.
Home >> Volvo >> 2012 >> C30 R Design L5-2.5L Turbo VIN 67 B5254T7 >> Repair and Diagnosis >> Brakes and Traction Control >> Antilock Brakes / Traction Control Systems >> Description and Operation >> System Overview

System Overview






System overview

Introduction

Brake control system Mark 60
The Mark 60 brake control system with the brake control module (BCM) is an electronic control system which prevents wheel lock up during braking (ABS). By preventing wheel lock up, steering control is maintained and maximum braking effect is utilized.
The brake control system is equipped with:
- Anti-lock Braking System
- Electrical Brake force Distribution (EBD) at the rear wheel brakes.
The brake control system, as a factory installed option, can be supplemented with:
- STC (Stability and Traction Control)
- DSTC (Dynamic Stability and Traction Control)
- TRACS AWD (Traction Control System All Wheel Drive), vehicles with AWD only.

EBD
The Electrical Brake force Distribution function is integrated in the ABS system. The function controls the braking forces electronically between the brake circuits front and rear wheels if the rear wheels are in danger of locking. This ensures optimal and stable braking.

STC
Stability and traction control system consisting of two parts:
- Traction control. Traction control (TC) is a traction control system which is integrated in the ABS-system. The traction control system distributes the driven power between the wheels so that the wheel with the best road traction receives the greatest amount of driven power. The system is mainly designed to assist when moving off on slippery surfaces at speeds up to approximately 60 km/h. Traction control has only a very limited effect at speeds above 60 km/h. To prevent damage to the brake calipers and discs, traction control is disabled if the brake discs become too hot. The traction control function is always engaged when the ignition is switched on. This function cannot be disabled manually.
- Stability control. The stability control (SC) system is integrated with the ABS system. It stabilizes the vehicle in the event of wheel spin. The brake control module (BCM) transmits a signal to the engine control module (ECM) to reduce engine torque until the slipping wheel(s) has/have stopped spinning. The stability function is always engaged when the ignition is switched on. Stability control can be engaged and disengaged manually using a switch on the tunnel console.

DSTC
DSTC (Dynamic Stability and Traction control) - a dynamic stability and traction control system which is integrated into the STC (stability and traction control) system.
The DSTC (Dynamic stability and traction control) system consists of the following:
- Traction Control - This function is described above under STC - Traction control above.
- Stability Control - This function is described above under STC - Stability control above.
- AYC (Active Yaw Control). The system is based upon a number of sensors which sense the driver's steering movements (steering wheel angle) and the directional, both straight and lateral, movement of the car. This information is used to correct the car in the event of oversteer or understeer.
DSTC is always engaged when the ignition is switched on. Stability control can be engaged and disengaged manually using a switch on the tunnel console. The same switch can be used to set the sensitivity of active yaw control (AYC). It can be either in normal mode or in wide slip mode.

TRACS AWD
This function is described in the STC-traction control section above. The TRACS AWD-function is always engaged when the ignition is switched on. (this function cannot be disabled manually).

Brake control module (BCM)




The control module is installed with the ABS hydraulic modulator and is positioned on the cowl panel in the engine compartment. The electrical valve coils for the different hydraulic valves are integrated into the control module.
The main function of the control module is to process the signals from the different sensors and to control the hydraulic pump and the electromagnetic hydraulic valves (inlet and outlet valves) in the ABS hydraulic modulator during:
- ABS control
- EBD control
- Traction Control
- Active yaw control (DSTC).
The control module communicates with directly connected components and other control modules via the Controller Area Network (CAN).
Control modules with DSTC communicate with the steering wheel angle sensor which is integrated into the steering wheel module (SWM). The steering wheel angle sensor detects the movement of the steering wheel (steering angle).
For further information, see Design and Function, steering wheel module (SWM).
The control module checks its calculations and all input and output signals using built-in diagnostic functions. When the vehicle is started and driven off, the control module checks that the signal from the wheel sensors is OK. When the car reaches 20 km/h (40 km/h if the stop (brake) lamp switch is activated), the control module briefly activates the pump motor and the hydraulic valves to check their function. The hydraulic pump can be heard at this time. This is completely normal. The ABS function can first be activated when the speed of the car exceeds approximately 7 km/h. Traction control however is available immediately. The control module also carries out a start-up test and then activates the warning lights in the combined instrument panel which are connected to the functions in the system.
A diagnostic trouble code (DTC) is registered in the internal memory of the control module if it detects a fault. At the same time, a number of values are stored. These are frozen at the time the fault occurred. Depending on the severity of the fault, certain functions may be partially or completely disengaged. A warning lamp lights in the driver information module (DIM) to inform the driver that a fault has occurred. A warning or information text will also be shown in the display in the driver information module (DIM). The text displayed depends on the fault (see the table). Diagnostic trouble codes (DTCs) and frozen values (extended diagnostic trouble code (DTC) information) can be read off using VIDA via the data link connector (DLC) in the vehicle.






Signals for control modules without DSTC (C30/S40/V50)
The table below summarizes the input signals to and output signals from the brake control module (BCM). The signal types are divided into directly connected signals, serial communication and controller area network (CAN) communication. The illustration below displays the same information with the Volvo component designations.










Signals for control modules with DSTC (C30/S40/V50/C70)
The table below summarizes the input signals to and output signals from the brake control module (BCM). The signal types are divided into directly connected signals, serial communication and controller area network (CAN) communication. The illustration below displays the same information with the Volvo component designations.










pro multis Credits:Operation CHARM About Operation CHARM