Drivetrain Control Module

DESCRIPTION 

Courtesy of CHRYSLER GROUP, LLC

1 - Drivetrain Control Module (DTCM) Bracket Nut

2 - DTCM

The Drivetrain Control Module (DTCM) is located on the bulkhead below the passenger instrument panel. It communicates with the vehicle systems through the Controller Area Network - Flexible Data 3 (CAN-FD3) bus to optimize the performance of the vehicles 4 Wheel Drive (4WD) functionality.

The DTCM is powered by the front Power Distribution Center (PDC).

OPERATION 

During normal operation of an active transfer case the Drivetrain Control Module (DTCM) control module learns and remembers the Clutch Engagement Point (Kiss Point), the position in the motor actuator's travel where torque begins to be transferred to the front wheels. The position is read using the encoder as a 0 to 5 volt signal. This information is written into the DTCM memory at ignition OFF. Over time the clutch pack wears and the Kiss Point changes in one direction (going from a lower voltage to a higher value).

POWER UP/DOWN 

The DTCM will power up with an OFF/ON transition of the ignition input.

The DTCM will power down when the vehicle ignition transitions from ON to OFF or if there are no system requirements that dictate the DTCM to remain active.

START-UP DIAGNOSTICS 

When the DTCM is activated, the internal circuitry will undergo a diagnostic procedure. The DTCM will examine all inputs and outputs for short circuits to ground, short circuits to battery and open circuits and will also verify proper Central Processing Unit (CPU) and memory operation. If a fault is detected, a message will be sent out over the CAN-C bus to the Instrument Panel Cluster (IPC) indicating that service is recommended.

After passing all diagnostic tests, the DTCM will receive and process inputs and produce the appropriate outputs. Proper monitoring of the DTCM inputs and outputs performance will continue.

INPUTS/OUTPUTS 

The following are inputs to the DTCM:

• Transfer case mode sensor signal.
• Direct battery feed.
• Ignition RUN sense.
• Sensor ground.
• DTCM ground.
• CAN-C bus messages.

The following are outputs of the DTCM:

• Transfer case motor brake control.
• 5V sensor supply.
• Transfer Case bidirectional motor control.
• Switched B(+) solenoid supply
• Transfer case motor brake control

TRANSFER CASE RANGE SELECT SWITCH INPUT (2WD, 4WD AUTO, 4WD LOCK, and 4WD LOW SELECT SWITCH) 

The Transfer Case Switch Module (TCSM) is responsible for notifying the Body Control Module (BCM) of switched operation over the Local Interface Network (LIN) bus. The BCM communicates the switched position to the DTCM via the CAN-Interior High Speed (CAN-IHS) bus.

The Transfer Case Range Switch (TCRS) input will provide the operator with the ability to place the transfer case in 2WD, 4WD AUTO, 4WD LOCK, 4WD LOW and Neutral. The NEUTRAL The TCRS is a momentary switch, and is a four position rotary contact switch. Both of the switches are provided through a resistor network for diagnostic purposes. The input will have an internal 1.0K +/- 1% pull-up resistor to 5V.

As the selected position in the switch varies and/or the NEUTRAL switch is depressed or not, the resistance within the and TCSM will vary. Hardware, software, and calibrations within the TCSM will be provided that interpret the external resistance between the TCSM switches voltage supply and TCRS inputs as given in the information below:

TRANSFER CASE MODE SENSOR SIGNAL 

The transfer case mode sensor signal input will provide the DTCM feedback about the position of the transfer case. The mode sensor is a linear analog position sensor with a 1.4K +/- 20% potentiometer and a 1 K +/- 20% wiper resistor that converts the motor shaft position into a multiplexed voltage. The mode sensor (on the active transfer case) is an active device where the sensor's current changes as the motor shaft position changes

TRANSFER CASE BIDIRECTIONAL MOTOR CONTROL (A AND B) 

This output will control a bi-directional Direct Current (DC) motor that controls a clutch pack in the transfer case that varies the torque transfer between the front and rear axles.

MODES OF OPERATION 

NORMAL OPERATION 

This mode is achieved when the ignition is in the RUN position and powers up the 5V regulator and generates the appropriate RESET for the microcontroller. This mode also includes any required power-up system checks.

SHUT DOWN MODE 

This mode is activated when the ignition is turned to the OFF position. The DTCM will perform any required shut down tasks prior to turning off the 5V regulator.

LIMP-IN MODE 

This mode is entered when the DTCM has detected an error condition that prevents the system from performing its required task. The DTCM operation will vary depending from modified operation to total system shut down based on the failure that has occurred.