Module, Drivetrain Control (DTCM): Operation

WARNING: This page is about a different car, the 2021 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.

BORG WARNER 44-40 TRANSFER CASE

The Borg Warner 44-40 transfer case allows torque to be variably applied to the front axle. By allowing variable application of torque between the front and rear axles, this all-wheel drive system can be used on dry pavement without the typical torsional windup that will occur with a standard four wheel drive transfer case. The drive system of this transfer case consists of an input shaft and drive sprocket/clutch assembly, and an output shaft and driven sprocket. The drive and driven sprockets are connected by a drive chain. The clutch assembly consists of a pulse width modulated electromagnetic actuator and a multi-disc clutch pack, and allows variable application of torque to the front axle based on traction and driving conditions. The input shaft of the transfer case is connected to the rear driveshaft, which drives the rear axle. The output shaft of the transfer case is connected to the front driveshaft, which drives the front axle.

DRIVETRAIN CONTROL MODULE (DTCM)

The Borg Warner 44-40 is a full time all-wheel drive transfer case with a fixed gear ratio. Depending on traction conditions, the DTCM will modulate the electromagnetic clutch assembly to vary the amount of torque applied to the front axle. Torque is transmitted through the input shaft to the clutch and drive sprocket assembly, and is transferred directly to the rear driveshaft, and to the output shaft and front driveshaft by the drive chain. The oil pump circulates gear lube throughout the case to provide clutch cooling, and the DTCM monitors the temperature of the transfer case with a temperature sensor.

FRONT AXLE DISCONNECT (FAD)

The Front Axle Disconnect Module (Solenoid) is controlled by the DTCM. The DTCM grounds the Drive Train Control relay, which provides Run/Start power to the Front Axle Disconnect Module. The DTCM controls the disconnect solenoid by grounding part of the solenoid, to switch from two wheel drive mode to all wheel drive mode, or vice versa. When the solenoid is grounded, the solenoid begins to move the shift fork and collar within the front axle intermediate shaft. In the all wheel drive mode, the shift collar connects the axle intermediate shaft to the axleshaft to supply engine power to both front wheels. In two wheel drive mode, the shift collar is disengaged from the intermediate shaft and the intermediate shaft is allowed to free-spin. When the two shafts are disengaged, the load on the engine is reduced, thereby providing better fuel economy and road handling. A position sensor is integral to the disconnect module to report disconnect operation to the DTCM. The disconnect module also is constantly grounded.

FAD TRIGGERS

The system uses the following signals to determine if the vehicle is experiencing an Antilock Braking System (ABS) event and engage the FAD:

ABS module outputs that brake intervention by ESP status.
Engine torque requests are active.
The DTCM engages the FAD when ambient temperatures drop below a calibrated value.
The DTCM disengages the FAD and defaults to 2WD whenever the transmission is shifted into N eutral.
The DTCM will engage the FAD whenever the transmission is in auto stick mode range of PRNDL.
If the DTCM calculates a difference in calibrated wheel speed versus actual wheel speeds, the DTCM will engage the AWD system to provide the best possible traction.
The DTCM uses the windshield wiper activation to trigger the FAD to engage.
The DTCM will trigger a change in the transfer case state to open when an ABS event is present.

MODE PERFORMANCE

The DTCM has a SPORT mode calibration that is enabled when requested by the driver. This SPORT mode is requested via the radio soft button or the Integrated Center Stack (ICS) hard button. The SPORT mode is intended to give the vehicle a more aggressive feel as opposed to NORMAL or STREET mode which is the default mode of the transfer case and FAD. When SPORT mode is requested:

FAD will connect if in 2WD or remain connected if already engaged.
FAD disengagement triggers are ignored until SPORT mode is deactivated and the system returns to normal.

MISMATCH TIRE SIZE

The DTCM has the capability of detecting a mini spare based on a difference of wheel speeds and will take the appropriate action to ensure that the AWD system integrity and maintain the maximum possible AWD function.