ABS Description and Operation
This vehicle is equipped with a Continental Teves Mk25 brake system. The electronic brake control module (EBCM) and the brake pressure modulator valve assembly are serviced separately. The brake pressure modulator valve assembly uses a 4 circuit configuration to control hydraulic pressure to each wheel independently.
Depending on options, the following vehicle performance enhancement systems are provided.
- Antilock brake system (ABS)
- Traction control
- Stability control
- Dynamic rear proportioning
- Hill start assist
- Hydraulic brake assist
- Trailer stability assist
- Optimized hydraulic braking system
The following components are involved in the operation of the above systems
- EBCM-The EBCM controls the system functions and detects failures. It supplies voltage to the solenoid valves and pump motor.
- Brake pressure modulator valve assembly-The brake pressure modulator valve assembly contains the following components: Hydraulic pump with pump motor Four isolation vales Four dump valves Two traction control/stability control supply valves Two traction control/stability control isolation valves Pressure sensor High pressure attenuators Low pressure accumulator
- Multi-axis acceleration sensor-The yaw rate, lateral acceleration and longitudinal acceleration sensors are combined into one multi-axis acceleration sensor, external to the EBCM. The EBCM receives serial data message inputs from the yaw rate, lateral acceleration and longitudinal acceleration sensor and activates stability control and hill start assist function depending on multi-axis acceleration sensor input.
- Steering angle sensor-The EBCM receives serial data message inputs from the steering angle sensor. The steering angle sensor signal is used to calculate the desired yaw rate.
- Traction control switch-Traction control and stability control are manually disabled or enabled by pressing the traction control switch.
- Wheel speed sensors-The EBCM sends a 12V reference voltage to each wheel speed sensor. As the wheel spins, the wheel speed sensor produces an alternating current square wave signal. The EBCM uses the frequency of the square wave signal to calculate the wheel speed.
Circuit/System Description
The body control module monitors the signal circuit for the traction control contact from the Sport Mode switch. When the switch is actuated once, the body control module sends a serial data message to the electronic control module for the brakes, requesting deactivation of traction control.
When the traction control switch is held down for 5 seconds, the body control module asks the electronic control module for the brakes to deactivate stability control. The electronic control module for the brakes then sends a serial data message to the instrument cluster requesting that the indicators showing traction control off and stability control off to be turned on so that the driver can see that deactivation has taken place.
Description and Operation
ABS DESCRIPTION AND OPERATION
The wheel speeds are detected by active wheel speed sensors and encoder rings. The encoder ring consists of permanent magnets. Each wheel speed sensor receives 12 V reference voltages from the electronic brake control module (EBCM). The wheel speed sensor produces changing current between 7-14 mA on the EBCM signal circuit. As the wheel spins, the EBCM uses the frequency of the square wave signal to calculate the actual wheel speed.
ABS DESCRIPTION AND OPERATION
The pump motor is an integral part of the brake pressure modulation valve and the pump motor relay is integrated in the electronic brake control module (EBCM). The pump motor relay is not activated during normal system operation. When the ABS, traction control or stability control operation is required, the EBCM activates the pump motor relay and turns the pump motor ON.
ABS DESCRIPTION AND OPERATION
The electronic brake control module monitors the brake pressure sensor, which is integrated in the unit with the brake pressure modulation valve. When the brake pedal is actuated, the body control module (BCM) sends a serial data message to the electronic brake control module (EBCM) concerning the brake pedal position. The EBCM compares the relationship between brake pedal position and the brake pressure recorded by the brake pressure sensor. This information is used to check the vehicle when electronic stability control takes place.
ABS DESCRIPTION AND OPERATION
When the brake pedal is actuated, the body control module (BCM) sends a serial data message to the electronic brake control module (EBCM) concerning the brake pedal position. The EBCM compares the relationship between brake pedal position and the brake pressure recorded by the brake pressure sensor. This information is used to check the vehicle when electronic stability control takes place.
ABS DESCRIPTION AND OPERATION
The yaw rate, lateral acceleration and longitudinal acceleration sensors are incorporated in one multi-axis acceleration sensor, external to the electronic brake control module (EBCM). The EBCM supplies a 12 V reference voltage to the multi-axis acceleration sensor. The multi-axis acceleration sensor communicates with the EBCM via the high speed controller area network (CAN) serial data circuit. The EBCM activates the stability control function depending on multi-axis acceleration sensor input.
ABS DESCRIPTION AND OPERATION
When traction control is active, the electronic brake control module (EBCM) sends a serial data message to the engine control module (ECM) requesting torque reduction. When certain ECM DTCs are set, the ECM will not be able to perform the torque reduction for traction control. A serial data message is sent to the EBCM indicating that traction control is not allowed.
ABS DESCRIPTION AND OPERATION
The solenoid valves are integral parts of the brake pressure modulator valve assembly. The brake pressure modulator valve assembly contains an isolation solenoid valve and a dump solenoid valve for each wheel and a traction control/stability control supply solenoid valve and isolation solenoid valve for each brake circuit. The solenoid valves are not engaged during normal system operation. When the ABS, traction control or stability control operation is required the electronic brake control module (EBCM) turns the required solenoid valves ON.
ABS DESCRIPTION AND OPERATION
The internal fault detection is handled inside the control module. No external circuits are involved.
ABS DESCRIPTION AND OPERATION
The electronic brake control module (EBCM) must be configured with the security code, CAN configuration data and vehicle options. If not properly configured after installation, the EBCM may set a DTC.
The internal fault detection is handled inside the control module. No external circuits are involved.
ABS DESCRIPTION AND OPERATION
The steering wheel angle sensor receives a ignition voltage from the electronic brake control module. The electronic brake control module receives serial data messages from the steering wheel's steering angle sensor, which identifies the position and turn direction of the steering wheel and uses the signal to confirm the driver's intended course.
ABS DESCRIPTION AND OPERATION
The wheel speeds are recorded by active wheel speed sensors and coding rings made up of permanent magnets. Each wheel speed sensor receives a reference voltage of 12 V from the electronic brake control module. Wheel speed sensors emit an AC voltage of 4 - 18 mA on the control module signal circuit. When the wheels rotate, the electronic brake control module uses the frequency of the square signal to calculate the wheel speed.
ABS DESCRIPTION AND OPERATION
When the ignition is turned ON, the microprocessor runs a diagnostic program to detect an internal fault when power up is commanded. If an internal malfunction is detected, the control module will set a DTC.
ABS DESCRIPTION AND OPERATION
The instrument cluster turns ON the ABS indicator for 5 seconds after ignition ON or when the electronic brake control module (EBCM) detects a fault and sends a serial data message to the instrument cluster commanding the indicator ON.
ABS DESCRIPTION AND OPERATION
The instrument cluster switches on the indicators for traction control/stability control, the indicators for winter road conditions and stability control OFF for 5 seconds when the ignition has been switched ON. The electronic brake control module (EBCM) issues a command to the instrument panel to switch off the electronic stability control/traction control system indicator (flashes) when the system is in traction control or anti-skid system mode. When the electronic brake control module (EBCM) detects a fault, a message is sent to the instrument panel showing that the anti-skid system/traction control indicates ON.
The body control module (BCM) monitors the traction control system signal from the SportMode contact. When the contact is depressed once, the BCM requests deactivation of the traction control system. When the contact is depressed for 5 seconds, the BCM requests deactivation of the anti-skid system. The EBCM transmits a signal to the instrument panel to indicate that the systems are deactivated and indicates ON to notify the driver that the system is deactivated.
ABS DESCRIPTION AND OPERATION