Circuit/System Description
The Body Control Module monitors the signal circuit from the Traction Control Switch. When the Traction Control Switch is pressed once, the Body Control Module will request the Electronic Brake Control Module via serial data to disable the traction control. When the Traction Control Switch is pressed and held for five seconds, the Body Control Module will request the Electronic Brake Control Module to disable the electronic stability control. The Electronic Brake Control Module will request the Instrument Cluster via serial data to turn the Traction Control Off and the Stability Control Off indicator ON to notify the driver of the deactivation.
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 ignition voltage from the electronic brake control module and provides an alternating current square wave signal to the electronic brake control module. As the wheel spins, the electronic brake control module uses the frequency of the square wave signal to calculate the wheel speed.
The pump motor is an integral part of the brake pressure modulator, while the pump motor relay is integral to the electronic brake control module. The pump motor relay is not engaged during normal system operation. When ABS operation is required the electronic brake control module activates the pump motor relay and battery voltage is provided to the pump motor.
The electronic brake control module monitors the brake pressure sensor which is integral to the brake pressure modulator. The body control module monitors the brake pedal position sensor signal when the brake pedal is applied and sends a serial data message to the electronic brake control module indicating the brake pedal position. The electronic brake control module compares the brake pressure to the brake pedal position and uses this information for vehicle stability control.
When the brake pedal is applied, the body control module sends a serial data message to the electronic brake control module in reference to the brake pedal positions. The electronic brake control module compares the correlation between the brake pedal position and the amount of brake pressure it senses from the brake pressure sensor, which is internal to the brake pressure modulator. It uses this information to control the vehicle during an stability control event.
The Lateral Accelerometer and the Yaw Rate Sensors are combined into one sensor called the Multi-axis Acceleration Sensor. The Electronic Brake Control Module supplies 12 V reference to the Multi-axis Acceleration Sensor. The Multi-axis Acceleration Sensor communicates with the Electronic Brake Control Module via serial data. The module activates the stability control function depending on Multi-axis Acceleration Sensor input.
Battery positive voltage is supplied to the electronic brake control module at all times through a 40 A fuse located in the underhood fuse block. The electronic brake control module uses this voltage to power the pump motor. The pump motor is an integral part of the brake pressure modulator, while the pump motor relay is integral to the electronic brake control module. The pump motor relay is not engaged during normal system operation. When the ABS, traction/stability operation is required the electronic brake control module activates the pump motor relay and turns the pump motor ON.
When traction control is active, the Electronic Brake Control Module sends a serial data message to the Engine Control Module requesting torque reduction. When certain Engine Control Module DTCs are set, the Engine Control Module will not be able to perform the torque reduction for traction control. A serial data message is sent to the Electronic Brake Control Module indicating that traction control is not allowed.
When the brake pedal is applied, the body control module sends a serial data message to the electronic brake control module in reference to the brake pedal positions. The electronic brake control module compares the correlation between the brake pedal position and the amount of brake pressure it senses from the brake pressure sensor, which is internal to the brake pressure modulator. It uses this information to control the vehicle during an stability control event.
The electronic brake control module monitors how often the traction control or the stability control system activates in order to calculate an estimate of the front brake discs temperature. In most cases the high temperatures are caused by extended traction control activation. If the electronic brake control module calculates that the front brake components temperatures are too high, the electronic brake control module will temporarily suspend the traction control system function until the front brake discs cool down.
The Lateral Accelerometer and the Yaw Rate Sensors are combined into one sensor called the Multi-axis Acceleration Sensor. The Electronic Brake Control Module supplies a 12 V reference to the Multi-axis Acceleration Sensor. The Multi-axis Acceleration Sensor communicates with the Electronic Brake Control Module via serial data. The module activates the stability control function depending on Multi-axis Acceleration Sensor input.
The electronic brake control module disables the traction and the stability control when other electronic control modules set DTCs for components that effect the operation of the brake system.
The Electronic Brake Control Module detects an internal malfunction.
The steering wheel angle sensor receives a 12 V reference from the electronic brake control module. The electronic brake control module receives serial data message inputs from the steering wheel angle sensor identifying the position and direction of the steering wheel rotation. The module utilizes this signal to calculate the driver intended driving direction.
The yaw rate, lateral acceleration and longitudinal acceleration sensors are combined into one multi-axis acceleration sensor, external to the electronic brake control module. The electronic brake control module supplies ignition voltage to the multi-axis acceleration sensor. The multi-axis acceleration sensor communicates with the electronic brake control module via serial data. The electronic brake control module activates the stability control function depending on the multi-axis acceleration sensor input. The transmission control module sets this DTC.
The Instrument Cluster turns the ABS indicator ON for five seconds after the ignition is turned ON, or when the Electronic Brake Control Module detects a fault and sends a serial data message to the Instrument Cluster commanding the indicator ON.
The Instrument Cluster illuminates the Traction/stability Control indicator, Traction Control Off indicator and Stability Control Off indicator for five seconds after the ignition is turned ON. When the Electronic Brake Control Module detects a fault it sends a serial data message to the Instrument Cluster commanding the Traction/stability Control indicator ON.
The Body Control Module monitors the signal circuit from the Traction Control Switch. When the Traction Control Switch is pressed once, the Body Control Module sends a serial data message to the Electronic Brake Control Module to disable the traction control system. When the Traction Control Switch is pressed and held for five seconds, the Body Control Module will request the Electronic Brake Control Module to disable the electronic stability control. The Electronic Brake Control Module will request the Instrument Cluster to turn the Traction Control Off and the Stability Control Off indicator ON to notify the driver of the deactivation.
ABS Description and Operation
This vehicle is equipped with the MGH 60 Mando electronic stability control antilock brake system. The electronic brake control module and the brake pressure modulator are serviced separately. The brake pressure modulator uses a four circuit configuration to control hydraulic pressure to each wheel independently.
The following vehicle performance enhancement systems are provided.
- ABS
- Electronic brake distribution
- Hill Start Hold
- Traction Control System
- Vehicle Stability Enhancement System
The following components are involved in the operation of the above systems.
- Electronic Brake Control Module-The electronic brake control module controls the system functions and detects failures.
- Brake pressure modulator-The brake pressure modulator contains the hydraulic valves and pump motor that are controlled electrically by the electronic brake control module. The brake pressure modulator uses a four circuit configuration with a diagonal split. The brake pressure modulator directs fluid from the reservoir of the master cylinder to the left front and right rear wheels and fluid from the other reservoir to the right front and left rear wheels. The diagonal circuits are hydraulically isolated so that a leak or malfunction in one circuit will allow continued braking ability on the other. The brake pressure modulator contains the following components: Pump motor Inlet valves (one per wheel) Outlet valves (one per wheel) Two traction control/stability control supply valves Two traction control/stability control isolation valves Brake pressure sensor
- Wheel speed sensors - The wheel speed sensors are Active sensors that receive a 12-volt power supply voltage from the electronic brake control module and provides an output signal to the module. As the wheel spins, the wheel speed sensor sends the electronic brake control module a DC square wave signal. The electronic brake control module uses the frequency of the square wave signal to calculate the wheel speed.
- Traction Control Switch - The vehicle stability enhancement system and the engine torque reduction function of the traction control system are manually disabled or enabled by pressing the taction traction control switch.
- Steering Wheel Angle Sensor - The electronic brake control module receives serial data message inputs from the steering wheel angle sensor. The steering wheel angle signal is used to calculate the driver intended driving direction.
- Multi-axis Acceleration Sensor - The yaw rate and lateral acceleration sensors are combined into one multi-axis acceleration sensor, external to the electronic brake control module. The electronic brake control module receives serial data message inputs from the yaw rate and lateral acceleration sensor and activates stability control depending on multi-axis acceleration sensor input.