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Home >> Ford >> 2021 >> Bronco Base, 2D Utility, 2.3L Eng VIN H, Part Time T/Case Control, Automatic Trans >> Repair and Diagnosis (Single Page) >> Brakes >> Traction Control >> Anti-Lock Brake System (Abs) And Stability Control >> Description And Operation >> Anti-Lock Brake System (ABS) and Stability Control - System Operation and Component Description >> System Operation >> Stability Control Features
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Stability Control Features

Curve Control 

Curve control enhances the vehicle's ability to follow the road when cornering severely or avoiding objects in the roadway. Curve control operates by reducing engine power and, if necessary, applying brakes to one or more of the wheels individually.

The ABS module continuously monitors the vehicle motion relative to the intended course. This is done by using sensors to compare the steering wheel input, yaw rate sensor input and lateral accelerometer input with the actual vehicle motion. The PSCM sends the steering wheel angle information to the ABS module over the FD-CAN. The RCM sends yaw rate sensor, lateral accelerometer and roll rate sensor information to the ABS module through the GWM over the HS-CAN2. If the ABS module determines from the inputs the vehicle is becoming unstable, the ABS module modulates brake pressure to the appropriate brake calipers by opening and closing the appropriate solenoid valves while activating the hydraulic pump motor. At the same time, the ABS module calculates how much engine torque reduction is required to help stabilize the vehicle and sends this torque reduction message to the PCM over the FD-CAN. The ABS module also sends a vehicle stability event message to the GWM over the FD-CAN which relays this 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 vehicle stability event message, it flashes the stability-traction control indicator (sliding car icon).

Once the vehicle instability has been corrected, the ABS module deactivates the hydraulic pump motor and the solenoid valves, and stops sending the traction event and torque reduction messages. The PCM returns engine timing and fuel injectors to normal operation and the IPC extinguishes the stability-traction control indicator (sliding car icon).

RSC does not operate with the transmission in REVERSE or with the transfer case in LOW range. The ABS module disables RSC if there are any wheel speed sensor, stability sensor or steering angle sensor Diagnostic Trouble Codes (DTCs) present in the ABS module. If there is a communication error between the ABS module and the PSCM or the ABS module and the RCM, RSC also is disabled. When RSC is disabled, the ABS module sends a message to the GWM over the FD-CAN. The GWM relays this message to the IPC over the HS-CAN3 to illuminate the stability-traction control indicator (sliding car icon).

Roll Stability Control (RSC) 

Roll stability control aids in preventing rollovers by detecting the roll motion of the vehicle and the rate at which it changes by applying the brakes to one or more wheels individually.

The ABS module continuously monitors the vehicle motion relative to the intended course. This is done by using sensors to compare the steering wheel input, yaw rate sensor input, lateral accelerometer input and roll sensor input with the actual vehicle motion. The PSCM sends the steering wheel angle information to the ABS module over the FD-CAN. The RCM sends yaw rate sensor, lateral accelerometer and roll rate sensor information to the ABS module through the GWM over the HS-CAN2. If the ABS module determines from the inputs the vehicle is becoming unstable, the ABS module modulates brake pressure to the appropriate brake calipers by opening and closing the appropriate solenoid valves while activating the hydraulic pump motor. At the same time, the ABS module calculates how much engine torque reduction is required to help stabilize the vehicle and sends this torque reduction message to the PCM over the FD-CAN. The ABS module also sends a vehicle stability event message to the GWM over the FD-CAN which relays this 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 vehicle stability event message, it flashes the stability-traction control indicator (sliding car icon).

Once the vehicle instability has been corrected, the ABS module deactivates the hydraulic pump motor and the solenoid valves, and stops sending the traction event and torque reduction messages. The PCM returns engine timing and fuel injectors to normal operation and the IPC extinguishes the stability-traction control indicator (sliding car icon).

RSC does not operate with the transmission in REVERSE, with the transfer case in LOW range or in Baja drive mode when stability controls have been disabled. The ABS module disables RSC if there are any wheel speed sensor, stability sensor or steering angle sensor Diagnostic Trouble Codes (DTCs) present in the ABS module. If there is a communication error between the ABS module and the PSCM or the ABS module and the RCM, RSC also is disabled. When RSC is disabled, the ABS module sends a message to the GWM over the FD-CAN. The GWM relays this message to the IPC over the HS-CAN3 to illuminate the stability-traction control indicator (sliding car icon).

Torque Vector Control 

Torque vectoring control applies the brakes on the inner driven wheel while in a curve for better traction to avoid an understeer or oversteer situation. Unlike ESC, torque vectoring control does not reduce engine RPM or slow the vehicle. It aids in controlling excessive wheel slip giving the vehicle improved cornering ability.

The ABS module continuously monitors and compares the rotational speed of the drive wheels in relation to the non-driven wheels. When torque vectoring control is needed, the ABS module modulates brake pressure to the appropriate brake calipers by opening and closing the appropriate solenoid valves while activating the hydraulic pump motor. At the same time, the ABS module sends a stability event message to the GWM over the FD-CAN which relays this message to the IPC over the HS-CAN3. When the IPC receives the traction event message, it flashes the stability-traction control indicator (sliding car icon).

Once the stability event is over, the ABS module deactivates the hydraulic pump motor and solenoid valves, and stops sending the traction event and torque reduction messages. The IPC extinguishes the stability-traction control indicator (sliding car icon).

Trailer Sway Control 

Trailer sway is the undesirable yaw force a trailer can apply to the towing vehicle. Trailer sway control is a unique function of the stability control system that uses steering wheel angle information and yaw rate information to determine if a trailer sway event is taking place. The PSCM sends the steering wheel angle information to the ABS module over the FD-CAN. The RCM sends yaw rate sensor and lateral accelerometer information to the ABS module also over the HS-CAN2 through the GWM. If the ABS module determines from the inputs a trailer sway event is taking place, the ABS module modulates brake pressure to the appropriate brake calipers by opening and closing the appropriate solenoid valves while the activating the hydraulic pump motor. At the same time, the ABS module calculates how much engine torque reduction is required to eliminate the trailer sway and sends this torque reduction message to the PCM over the FD-CAN. The ABS module also sends a trailer sway event message to the GWM over the FD-CAN which relays this 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 vehicle stability event message, it flashes the stability-traction control indicator (sliding car icon) and displays TRAILER SWAY REDUCE SPEED in the message center.

Once the trailer sway has been corrected, the ABS module deactivates the hydraulic pump motor and the solenoid valves, and stops sending the traction event and torque reduction messages. The PCM returns engine timing and fuel injectors to normal operation and the IPC extinguishes the stability-traction control indicator (sliding car icon) and stops displaying the trailer sway message in the message center. Trailer sway control only activates when vehicle speed is greater than 65 km/h (40 mph). Any malfunction disabling RSC also disables trailer sway control.

The driver can enable and disable the trailer sway control feature using the message center. For additional information, refer to the Owner's Literature.

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