System Operation: AdvanceTrac

WARNING: This page is about a different car, the 2016 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

The AdvanceTrac system 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 calipers 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 to the GWM over the HS-CAN2 which relays the message to the PCM over the HS-CAN1. The ABS module also sends a traction event message to the GWM over the HS-CAN2 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 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 fuel injectors to normal operation and the IPC extinguishes the stability-traction control indicator (sliding car icon). Once vehicle speed exceeds 100 km/h (62 mph), traction control is accomplished only through the PCM torque control.

The traction control system can be disabled by the driver using the stability-traction control switch. This is independent of ABS which cannot be disabled by the driver. The traction control switch is hard-wired to the IPC, when the driver presses the traction control switch, the switch sends a ground signal to the IPC. The IPC responds by illuminating the stability-traction control disabled indicator (sliding car OFF icon) and by sending a message to the GWM over the HS-CAN3. The GWM relays this message to the ABS module over the HS-CAN2. The ABS module takes no further action in regards to traction control until the driver presses the switch again in the same ignition cycle or until the ignition is cycled from OFF to ON. For additional information on disabling the traction control feature, refer to Disabling AdvanceTrac.

The ABS module disables traction control if there are any wheel speed sensor or solenoid valve Diagnostic Trouble Codes (DTCs) present in the ABS module. Traction control is also disabled if there is a communication error between the ABS module and the PCM. When traction control is disabled, the ABS module sends a message to the GWM over the HS-CAN2. The GWM relays this message to the IPC over the HS-CAN3 to illuminate the stability-traction control indicator (sliding car icon).

Electronic Stability Control (ESC)

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 and the yaw rate sensor input with the actual vehicle motion. The PSCM sends the steering wheel angle information to the ABS module over the HS-CAN2. The RCM sends yaw rate sensor and lateral accelerometer information to the ABS module also over the HS-CAN2. If the ABS module determines from the inputs the vehicle is unable to travel in the intended direction, it modulates brake pressure to the appropriate brake calipers 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 help stabilize the vehicle and sends this torque reduction message to the GWM over the HS-CAN2 which relays the message to the PCM over the HS-CAN1. The ABS module also sends a vehicle stability event message to the GWM over the HS-CAN2 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 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 fuel injectors to normal operation and the IPC extinguishes the stability-traction control indicator (sliding car icon).

The ESC can be disabled by the driver using the stability-traction control switch. This is independent of ABS which cannot be disabled by the driver. The stability-traction control switch is hard-wired to the IPC, when the driver presses the stability-traction control switch, the switch sends a ground signal to the IPC. The IPC responds by illuminating the stability-traction control disabled indicator (sliding car OFF icon) and by sending a message to the GWM over the HS-CAN3. The GWM relays this message to the ABS module over the HS-CAN2. The ABS module takes no further action in regards to stability-traction until the driver presses the switch again in the same ignition cycle, the ignition is cycled from OFF to ON or vehicle speed exceeds 56 km/h (35 mph). For additional information on disabling the traction control feature, refer to Disabling AdvanceTrac.

ESC does not operate with the transmission in REVERSE or with the transfer case in 4WD low. The ABS module disables ESC 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, ESC also is disabled. When ESC is disabled, the ABS module sends a message to the GWM over the HS-CAN2. The GWM relays this message to the IPC over the HS-CAN3 to illuminate the stability-traction control indicator (sliding car icon).