Broadcast Message | Originating Module | Message Purpose |
|---|---|---|
Vehicle longitudinal acceleration data | RCM | This message provides the ABS module with the current vehicle longitudinal acceleration data and notifies the ABS module if the data is valid or invalid. The ABS module uses the longitudinal acceleration data for ESC feature operation. |
Vehicle yaw rate data | RCM | This message provides the ABS module with the current vehicle yaw rate data and notifies the ABS module if the data is valid or invalid. The ABS module uses the yaw rate data for ESC feature operation. |
Anti-Lock Braking
The ABS module continuously monitors brake pedal input, longitudinal vehicle motion and the rotational speed of each wheel. The ABS module receives the brake pedal input from the PCM and the longitudinal acceleration sensor information from the RCM. The PCM sends the brake pedal input message to the GWM over the HS-CAN1, the GWM relays the message to the ABS module over the HS-CAN2. The RCM sends the longitudinal acceleration sensor message directly to the ABS module over the HS-CAN2. Wheel speed information is received by the ABS module using 4 wheel speed sensors. When the ABS module detects an impending wheel lock during a braking event, the ABS module modulates brake pressure to the appropriate brake caliper by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. Once the affected wheel returns to the desired speed, the ABS module returns the solenoid valves in the HCU to their normal position and deactivates the hydraulic pump motor.
When the ABS module is initialized (ignition ON), a preliminary electrical check of the wheel speed and brake booster vacuum sensors is carried out, and the hydraulic pump motor is activated for approximately one-half second. During this time, a buzzing or humming noise may be heard and a vibration may be felt in the brake pedal, this is a normal condition. During the module initialized self-test, the pump motor check is carried out at approximately 10 km/h (6.2 mph). Any malfunction detected in the system causes the ABS module to set a DTC, disable the ABS function and send a message to the IPC to illuminate the ABS warning indicator. The base hydraulic power assist braking system functions normally.
Electronic Brake Force Distribution (EBD)
On initial application of the brake pedal, full pressure is applied to the rear brakes. The ABS module then uses wheel speed sensor inputs to evaluate rear wheel slip. Once the rear wheel slip exceeds a predetermined threshold, the ABS module commands the HCU to close the appropriate isolation valves to hold the rear brake pressure constant while allowing the front brake pressure to build. This creates a balanced braking condition between the front and rear wheels. If the rear wheel slip continues and exceeds a second predetermined threshold, the ABS module commands the HCU to open the dump valves to decrease the rear brake pressure and allow the rear wheels to recover. A slight bump sensation may be felt in the brake pedal when EBD is active.
If the ABS is disabled due to a DTC being present in the ABS module, EBD continues to function unless the DTC is for wheel speed sensors or the HCU. When EBD is disabled, the ABS warning indicator, the red brake warning indicator and stability-traction control indicator (sliding car icon) illuminate.
AdvanceTrac
The AdvanceTrac feature is comprised of the traction control and ESC features.
Traction Control
The ABS module continuously monitors and compares the rotational speed of the drive wheels in relation to the non-driven wheels. When the drive wheels begin to spin faster than the non-driven wheels, the ABS module modulates brake pressure to the appropriate brake caliper(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module calculates how much engine torque reduction is required to eliminate the wheel slip and sends this torque reduction message along with a traction event message to the GWM over the HS-CAN2. The GWM sends the engine torque reduction message to the PCM over the HS-CAN1 and the traction event message to the IPC over the HS-CAN3. When the PCM receives the torque reduction message, it adjusts engine timing and decreases fuel injector pulses to reduce the engine torque to the requested level. When the IPC receives the traction event message it flashes the stability-traction control indicator (sliding car icon). Once the driven wheel speed returns to the desired speed, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and stops sending the traction event and torque reduction messages. The PCM returns engine timing and
2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.