Description And Operation: PHEV: Notes

DESCRIPTION 

Courtesy of CHRYSLER GROUP, LLC

The Antilock Brake System OBD (ABSO) includes the following components:

1.	Refer to ANTILOCK BRAKE SYSTEM OBD (ABSO) MODULE .
2.	Refer to BRAKE FLUID RESERVOIR .
3.	Refer to ACTUATOR CONTROL UNIT (ACU) .

OPERATION 

The ABS has multiple subsystems including, Traction Control System (TCS), Brake Assist System (BAS), Electronic Stability Control (ESC), Hill Start Assist (HSA), Electronic Roll Mitigation (ERM), Trailer Sway Control (TSC), and Hill Descent Control (HDC), Cornering Brake Control (CBC), Drag Torque Control, and Off-Road ABS (ORA) ESC. All of these systems work together to enhance vehicle stability and control in various driving conditions.

A brief explanation of each subsystem follows:

• BRAKE ASSIST SYSTEM  - The BAS is designed to optimize the vehicle's braking capability during emergency braking maneuvers. The system detects an emergency braking situation by sensing the rate and amount of brake application and then applies optimum pressure to the brakes.
• CORNERING BRAKE CONTROL  - The CBC function reduces the over steer tendency of the vehicle during an ABS braking maneuver in a curve by providing an anti-yaw moment through reduction of front inner wheel pressure. The ESC shall pay attention to possible torque steering disturbance and noise actuations. CBC is active during braking in curve maneuvers or when ABS function is active. CBC is not active when ABS function is not active.
• DRAG TORQUE CONTROL  - The Drag Torque Control function tries to avoid locking of the driving axle during throttle-off maneuvers due to engine braking torque. Drag Torque Control is active during throttle-off maneuvers. Drag Torque Control activates when the locking tendency of a driving wheel exceeds the target value.
• ELECTRONIC ROLL MITIGATION  - The ERM system monitors steering wheel input and the speed of the vehicle. When the rate of change of the steering wheel angle and vehicle's speed are sufficient to potentially cause wheel lift, the appropriate brake will apply and engine power may be reduced to lessen the chance that wheel lift will occur. ERM will only intervene during very severe or evasive driving maneuvers.
• ELECTRONIC STABILITY CONTROL  - The ESC system enhances directional control and stability of the vehicle using steering wheel angle, yaw (turning) rate and lateral acceleration sensors (combined into Dynamics Sensor). Using signals from these sensors, in addition to individual wheel speed sensor signals the ESC corrects for over/under steering of the vehicle by applying the brake of the appropriate wheel to assist in counteracting an over/under steer condition. Engine power may also be reduced to help the vehicle maintain the desired path. Certain components may also reference ESP, ESC, or use the traction control symbol.
• HILL DESCENT CONTROL  - The HDC system maintains vehicle speed while descending hills in off-road driving conditions by applying the brakes when necessary. HDC can only be enabled when the transfer case is in the "4WD LOW" position and the vehicle speed is less then 48 km/h (30 mph). If these conditions are not met while attempting to use the HDC feature, the HDC indicator light will flash ON/OFF. The HDC indicator lamp will be on solid when HDC is enabled. When enabled, HDC senses the terrain and activates when the vehicle is descending a hill. HDC is only intended for low speed off-road driving. The accelerator pedal will override HDC at any time.
• HILL START ASSIST 

  -

  NOTE:

  The HSA system does not operate on an automatic transmission vehicle in the neutral position.

  The HSA system is designed to maintain the level of brake pressure for a short period of time after the brake pedal is released so that the vehicle does not roll on a hill between releasing the brake pedal and applying the accelerator pedal. The following must be true for HSA to activate:

  • The vehicle must be stopped with the brake applied
  • The vehicle must be at a eight percent or greater incline (three percent for manual transmissions)
  • Gear selection must match uphill direction (forward gear for uphill, reverse for backing uphill)
• OFF-ROAD ABS (ORA) ESC  - On deformable surfaces (gravel, sand, and others), a specific Off-Road ABS calibration with higher wheel slip targets may be used to improve the ABS stopping distance. A larger wheel slip will help take advantage of the wedge effect of the deformable surface in front of the tires. Off-Road ABS is automatically enabled if the vehicle has terrain switch setting(s) for deformable surfaces, or it may be enabled if the transfer case is switched to low range. The ORA logic may also be used if the ESC detects a deformable surface based on information from the wheel speed sensors, longitudinal acceleration sensor, and brake torque model. The deeper wheel slip targets used in ORA are dependent on vehicle speed, steering wheel angle, and surface mu estimation. The ORA logic is not intended to be used on dry or wet asphalt, packed snow or ice.
• TRACTION CONTROL  - This system monitors the amount of wheel spin of each of the driven wheels. If wheel spin is detected, brake pressure is applied to the slipping wheel(s) to provide enhanced acceleration and stability.
• TRAILER SWAY CONTROL  - The TSC system uses sensors in the vehicle to recognize an excessively swaying trailer and will take the appropriate actions to attempt to stop the sway. The system may reduce engine power and apply the brake of the appropriate wheel(s) to counteract the sway of the trailer. TSC will become active automatically once an excessively swaying trailer is recognized.