Transfer Case - NV244 Transfer Case: Overview Dodge Dakota III

Scheme 98

The NV244 (1) is an electronically controlled full and part-time transfer case with no two wheel drive operation. (Scheme 98)

A differential in the transfer case is used to control torque transfer to the front and rear axles. A low range gear reduction system provides increased low speed torque capability for off road operation. The low range provides a 2.72:1 reduction ratio.

The geartrain is mounted in two aluminum case halves attached with bolts. The mainshaft front and rear bearings are mounted in aluminum retainer housings bolted to the case halves.

OPERATION

The input gear is splined to the transmission output shaft. The input gear drives the mainshaft through the planetary assembly and range sleeve. The front output shaft is operated by a drive chain that connects the shaft to a drive sprocket on the mainshaft. The drive sprocket is engaged/disengaged by the mode fork, which operates the mode sleeve and hub. The sleeve and hub are not equipped with a synchronizer mechanism for shifting.

During normal vehicle operation, the Front Control Module (FCM) monitors the mode sensor outputs at least every 2 milliseconds when the shift motor is stationary or active.

Refer to SECTOR ANGLES vs. TRANSFER CASE POSITION table for the relative angles of the transfer case shift sector versus the interpreted transfer case gear operating mode.

SECTOR ANGLES vs. TRANSFER CASE POSITION

Note. All the parameter voltages referred to in the following information are calibrated items in the controller software and are subject to change.

Note. For a further explanation of Phase 1 through 3 shifting, Refer to OPERATION .

The following information describes the different mode sensor positions

1. 4LO TARGET REGION - The position shall be considered 4LO if the voltage is greater than or equal to encoder_4LO_min Volts and it is also less than or equal to encoder_4LO_max Volts.
2. 4LO SHIFT LIMIT - During Phase 2 and Phase 3 shifting, shifts may become unidirectional when a voltage is less than or equal to encoder_4LO_min Volts has been reached.
3. 4LOCK TARGET REGION - The position shall be considered 4LOCK if the voltage is greater than or equal to encoder_4LOCK_min Volts and it is also less than or equal to encoder_4LOCK_max Volts.
4. NEUTRAL TARGET REGION - The position shall be considered NEUTRAL if the voltage is greater than or equal to encoder_Neutral_min Volts and it is also less than or equal to encoder_Neutral_max Volts.
5. AWD TARGET REGION - The position shall be considered AWD if the voltage is greater than or equal to encoder_AWD_min Volts and it is also less than or equal to encoder_AWD_max Volts.
6. AWD SHIFT LIMIT - During Phase 2 and Phase 3 shifting, shifts may become unidirectional when a voltage is greater than or equal to encoder_AWD_min Volts has been reached.

The mode sensor position will be considered invalid by the FCM if the voltage is greater than or equal to encoder_High_Range_Limit Volts or if it is less than or equal to encoder_Low_Range_Limit Volts.

Refer to MODE SENSOR VOLTAGES - NV244 table for the mode sensor voltages.

MODE SENSOR VOLTAGES - NV244

Scheme 99

1. Raise vehicle.
2. Remove front propeller shaft. «Refer to REMOVAL»(ref-247643-S13692291362007020100000).
3. Remove front output shaft companion flange.
4. Remove seal (1) from front case with suitable pry tool. (Scheme 99)

Shifting in the transfer case occurs when a Pulse Width Modulated (PWM) voltage is supplied to the shift motor by the Front Control Module (FCM). A linear analog position sensor located inside the shift motor, provides the FCM with the motors' angular, rotational position. With this information, the FCM continuously knows the motors' position, and therefore allows it to accurately control the motors' operation, including voltage polarity which is used to control motor direction.

DESCRIPTION

The selector switch assembly is mounted in the right side of the vehicle's Instrument Panel (IP) and consists of a rotary knob connected to a resistive network for the mode and range shift selections. Also located in this assembly is a recessed, normally open momentary switch for making shifts into and out of transfer case NEUTRAL. A pen, or similar instrument, is used to make a NEUTRAL shift selection, thus reducing the likelihood of an inadvertent shift request.

As the position of the selector switch varies, the resistance between the Mode Sensor supply voltage pin and the Mode Sensor output will vary. Hardware, software, and calibrations within the Front Control Module (FCM) are provided that interpret the selector switch resistance as given in the table below: SELECTOR SWITCH INTERPRETATION .

SELECTOR SWITCH INTERPRETATION

The internal structure and function of the selector switch is such that the connection is made to the Open/Diagnostic resistor before the connection to the individual position resistors is broken. Because of this characteristic, if the resistance between the Mode Sensor supply voltage pin and the Mode Sensor output pin is >19 k/ohms, the position resistor is open.