Transfer Case - NV233 Transfer Case: Overview Dodge Dakota III

Scheme 16

The NV233 (1) is an electronically controlled part-time transfer case with a low range gear reduction system. The NV233 has three operating ranges plus a NEUTRAL position. The low range system provides a gear reduction ratio for increased low speed torque capability. (Scheme 16)

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. 4HI TARGET REGION - The position shall be considered 4HI if the voltage is greater than or equal to encoder_4HI_min Volts and it is also less than or equal to encoder_4HI_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. 2WD TARGET REGION - The position shall be considered 2WD if the voltage is greater than or equal to encoder_2WD_min Volts and it is also less than or equal to encoder_2WD_max Volts.
6. 2WD SHIFT LIMIT - During Phase 2 and Phase 3 shifting, shifts may become unidirectional when a voltage is greater than or equal to encoder_2WD_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 - NV233 table for the mode sensor voltages.

MODE SENSOR VOLTAGES - NV233

Scheme 17

1. Raise vehicle.
2. Remove rear propeller shaft. «(Refer to REMOVAL)»(ref-247643-S13692291362007020100000)
3. Using a suitable pry tool or slide-hammer mounted screw, remove the rear retainer seal.
4. Using Remover 8158 (1), remove the bushing from rear retainer. (Scheme 17)

Scheme 18

Scheme 19

1. Clean fluid residue from sealing surface and inspect for defects.
2. Position replacement bushing in rear retainer with fluid port in bushing aligned with slot in retainer.
3. Using Installer 8157 (2), drive bushing (1) into retainer until installer seats against case. (Scheme 18) 1 - SPECIAL TOOL C-4171 2 - SPECIAL TOOL D-163
4. Using Installer D-163 (2), install seal in rear retainer. (Scheme 19)
5. Install the rear propeller shaft. «(Refer to INSTALLATION)»(ref-247643-S00908099292007020100000)
6. Verify proper fluid level.
7. Lower vehicle.

Scheme 20

The shift motor (1) is an electromechanical device consisting of a DC permanent magnet motor, gear train, and an analog position sensor. The shift motors' overall function is to move and lock a gear that moves the mode and range forks found in the transfer case. This allows the transfer case to be shifted electrically to multiple operating positions (4HI, 2WD, N (neutral), and 4LO). The operating current of the shift motor under stall conditions is 30 amps maximum at 72° F with 13.5 volts, at the motor leads. (Scheme 20)

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 >19k ohms, the position resistor is open.