Overhaul - NV144: Other Dodge Durango II

OPERATING RANGES

Transfer case operating ranges are

1. AWD (All-wheel drive)
2. 4HI (4-wheel drive)

The AWD range is for use on any road surface at any time.

The 4HI range is for off road use only. It is not for use on hard surface roads. The only exception being when the road surface is wet or slippery or covered by ice and snow.

SHIFT MECHANISM

Operating ranges are selected with a dash mounted shift selector switch. The shift selector switch provides a input to the Front Control Module (FCM) to indicate the driver's desire to change operating ranges. The FCM uses this input, along with input from the transfer case mounted mode sensor and information from the vehicle's BUS, to determine if a shift is permitted. If the FCM decides the shift is permitted, the FCM controls the shift motor (2), mounted to the exterior of the transfer case, to perform the shift.

Scheme 156

CLEANING

Clean the transfer case parts with a standard parts cleaning solvent. Remove all traces of sealer from the cases and retainers with a scraper and 3M(tm) all purpose cleaner. Use compressed air to remove solvent residue from oil feed passages in the case halves, retainers, gears, and shafts.

SHIFT FORK AND SLEEVE

Check condition of the shift fork and mode fork shift rail. Minor nicks on the shift rail can be smoothed with 320-400 grit emery cloth.

Inspect the shift fork wear pads (1). The mode fork pads are serviceable and can be replaced if necessary.

Scheme 157

FRONT OUTPUT SHAFT AND DRIVE CHAIN

Inspect the sprocket teeth and bearing surfaces. Minor nicks on the teeth can be smoothed with an oilstone. Use 320-400 grit emery to smooth minor scratches on the shaft bearing surfaces. Replace the shaft if the splines are damaged, bearing surfaces are scored, or if any sprocket teeth are cracked or broken.

Examine the drive chain and shaft bearings. Replace the chain and both sprockets if the chain is stretched, distorted, or if any of the links bind. Replace the bearings if rough, or noisy.

FRONT/REAR CASES

Inspect the cases for wear and damage. Replace the input shaft seal; do not reuse it.

Check case condition. If leaks were a problem, look for gouges and severe scoring of case sealing surfaces. Also make sure the front case mounting studs are in good condition.

Check the front case mounting studs and vent tube. The tube can be secured with Loctite(tm) 271 or 680 if loose. The stud threads can be cleaned up with a die if necessary. Also check condition of the fill/drain plug threads in the rear case. The threads can be repaired with a thread chaser or tap if necessary. Or the threads can be repaired with Helicoil(R) stainless steel inserts if required.

SHAFT ANGLE vs. TRANSFER CASE POSITION

SHAFT ANGLE

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. 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.
2. 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.
3. 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.

If FCM looses the encoder signal in a NV144 transfer case during a shift, the FCM will respond with a shift back in the opposite direction of travel to first attempt to find the encoder signal. If the signal is not found, the FCM will drive motor in AWD direction for 1 second.

Refer to MODE SENSOR VOLTAGES - NV144 table for the mode sensor voltages.

MODE SENSOR VOLTAGES - NV144

MODE SENSOR VOLTAGES

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.