Four Wheel Drive (4WD) Systems: Overview Ford Fusion I рестайлинг

Principles of Operation

The vehicle is equipped with an All-Wheel Drive (AWD) system, also referred to as active torque coupling (ATC) , that is always active and requires no driver input. The system has no Mode Select Switch (MSS).

The system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is sent to the front wheels. If wheel slip between the front and rear wheels is detected or if the vehicle is under heavy acceleration (high- throttle position), the AWD system increases torque to the rear wheels to prevent or control wheel slip.

The system consists of a Power Transfer Unit (PTU), 4X4 control module, rear axle and a solenoid actuated Active Torque Coupling (ATC) device. Based on the amount of current sent to the clutch, the module varies the torque sent to the rear wheels by sending a duty cycle to the ATCATC device, located inside the rear axle. For concerns with the PTU, refer to TRANSFER CASE - POWER TRANSFER UNIT (PTU) article.

The 4X4 control module also provides the brake system with its current clutch duty cycle and determines whether or not the brake system may take command of the clutch duty cycle.

Note. The ATC solenoid is not repairable. If a new component is required, the ATC solenoid and rear axle are installed as an assembly. Refer to REAR DRIVE AXLE/DIFFERENTIAL article.

The active, on-demand AWD system uses data from other systems as inputs to the 4X4 control module. The 4X4 control module uses the inputs to determine the appropriate amount of current to send to the ATC solenoid that delivers the desired torque to the rear wheels. Specific inputs to the 4X4 control module are

1. Accelerator pedal position via the High Speed Controller Area Network (HS-CAN)
2. Transaxle range from the Transmission Control Module (TCM) via the HS-CAN
3. Brake system status from the ABS module via the HS-CAN
4. Wheel speed from all 4 wheels from the ABS module via the HS-CAN

4X4 control module outputs are

1. Solid-state clutch (pulse-width modulated signal) to the ATC solenoid
2. Percent of torque transfer commanded signal to the ABS module via the HS-CAN
3. Torque request available signal to the ABS module via the HS-CAN

Heat Protection Mode - During very extreme off-road operation, the Pulse-Width Modulation (PWM) system utilizes a heat protection mode to protect the Active Torque Coupling (ATC) solenoid (part of rear axle) from damage. If the system detects an overheat condition, it enters a locked mode. If the heat in the system continues to rise once in the locked mode, the 4X4 control module disables the ATC solenoid. Allow the system to cool down at least 10 minutes with the ignition switch in the ON position.

Normal Operation

The All-Wheel Drive (AWD) system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is delivered to the front wheels. If wheel slip between the front and rear wheels is detected, or if the vehicle is under heavy acceleration, the AWD system increases torque to the rear wheels to prevent or control wheel slip.

This pinpoint test is intended to diagnose the following

1. AWD system concern without on-demand or continuous DTCs

If the 4X4 control module observes an overpower or under power voltage condition, DTCs are set and the 4X4 control module may not allow Four-Wheel Drive (4WD) operation.

1. DTC B1317 Battery Voltage High - When the 4X4 control module detects battery voltage greater than 16 volts for at least 10 seconds, this DTC is set.
2. DTC B1318 Battery Voltage Low - When the 4X4 control module detects battery voltage less than 9 volts for at least 10 seconds, with the engine running at 1,500 RPM or greater, this DTC is set.

This pinpoint test is intended to diagnose the following

1. Fuses
2. Wiring, terminals or connectors
3. 4X4 control module

The All-Wheel Drive (AWD) system uses data from other systems as inputs to the 4X4 control module. The 4X4 control module uses the inputs to determine the appropriate duty cycle to send to the Active Torque Coupling (ATC) solenoid (part of rear axle) that delivers the desired torque to the rear wheels. Specific inputs to the 4X4 control module are: accelerator pedal position output from the PCM, transmission range from the Transmission Control Module (TCM), brake system status and all 4 wheel speeds from the ABS module. Communication between the 4X4 control module and other modules is obtained through the High Speed Controller Area Network (HS-CAN). If the 4X4 control module loses communication with, or receives invalid data from any of the necessary modules, DTCs are set and the 4X4 control module may not allow Four-Wheel Drive (4WD) operation.

1. DTC U0415 Invalid Data Received from Anti-lock Brake System (ABS) Control Module - When the 4X4 control module receives invalid HS-CAN bus data or invalid wheel speed(s) from the ABS module for more than 5 seconds, this DTC is set.

This pinpoint test is intended to diagnose the following

1. ABS module

The All-Wheel Drive (AWD) system uses data from other systems as inputs to the 4X4 control module. The 4X4 control module uses the inputs to determine the appropriate duty cycle to send to the Active Torque Coupling (ATC) solenoid (part of rear axle) that delivers the desired torque to the rear wheels. If the 4X4 control module loses communication with, or receives invalid data from any of the necessary modules, DTCs are set and the 4X4 control module may not allow Four-Wheel Drive (4WD) operation.

1. DTC P1824 4-Wheel Drive Clutch Relay Circuit Failure - When the 4X4 control module detects a short to ground on the ATC solenoid feedback circuit, this DTC is set.
2. DTC P1825 4-Wheel Drive Clutch Relay Open Circuit - When the 4X4 control module detects an open or short to ground on the ATC solenoid command or feedback circuit for more than 2 seconds, this DTC is set.

This pinpoint test is intended to diagnose the following

1. Tire/axle out of range
2. ATC solenoid (part of rear axle)
3. 4X4 control module
4. Power Transfer Unit (PTU)
5. Wiring, terminals or connectors

The All-Wheel Drive (AWD) system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is sent to the front wheels. If wheel slip between the front and rear wheels is detected or the vehicle is under heavy acceleration, the AWD system increases torque to the rear wheels.

This pinpoint test is intended to diagnose the following

1. Rear axle
2. Wheels/tires
3. PCM
4. ABS module
5. 4X4 control module
6. Circuitry

The All-Wheel Drive (AWD) system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is sent to the front wheels. If wheel slip between the front and rear wheels is detected or the vehicle is under heavy acceleration, the AWD system increases torque to the rear wheels.

1. DTC P1635 Tire/Axle Out of Acceptable Range - When the 4X4 control module detects inappropriate mini spare or road wheels/tires (greater than 7% across the front and rear axle or 14% at one wheel) installed, this DTC is set.

This pinpoint test is intended to diagnose the following

1. Wheels/tires
2. Wheel speed sensors
3. ABS module
4. 4X4 control module