1998 DODGE RAM 1500 Transfer case installation

EXTENSION HOUSING SEAL
REMOVAL
(1) Raise and support vehicle.
(2) Remove rear propeller shaft. (Refer to 3 - DIF-
FERENTIAL & DRIVELINE/PROPELLER SHAFT/
PROPELLER SHAFT - REMOVAL)
(3) Using a suitable pry tool or slide-hammer
mounted screw, remove the extension housing seal.
INSTALLATION
(1) Clean fluid residue from sealing surface and
inspect for defects.
(2) Using Installer D-163, install seal in extension
housing (Fig. 79).
(3) Install propeller shaft. (Refer to 3 - DIFFER-
ENTIAL & DRIVELINE/PROPELLER SHAFT/PRO-
PELLER SHAFT - INSTALLATION)
(4) Verify proper transfer case fluid level.
(5) Lower vehicle.
Installer, Bushing - 5066
Installer, Bearing - 6953
Cup - 8148
Installer - 8840
Installer, Seal - 8841
Fig. 79 Install Rear Seal in Extension Housing
1 - SPECIAL TOOL C-4171
2 - SPECIAL TOOL D-163
21 - 536 TRANSFER CASE - NV244 GENIIDR
TRANSFER CASE - NV244 GENII (Continued)

(4) Remove the front output shaft seal slinger by
bending (Fig. 83) the slinger away from the transfer
case.
(5) Using a suitable pry tool, remove the slinger
from the output shaft using care not to damage the
shaft.
(6) Using a screw and a slide hammer, remove the
front output shaft seal.
INSTALLATION
(1) Install the new front output shaft seal with
Installer MB991168A
(2) Install the front output shaft seal slinger with
Installer 8840. Install the slinger onto the shaft until
the tool contacts the rear of the output shaft.
(3) Install a new seal boot clamp onto the seal
boot.
(4) Install the seal boot and clamp onto the slinger
hub and tighten the clamp with Crimp Tool
C-4975-A.
(5) Install front propeller shaft (Refer to 3 - DIF-
FERENTIAL & DRIVELINE/PROPELLER SHAFT/
PROPELLER SHAFT - INSTALLATION).
MODE SENSOR
DESCRIPTION
The transfer case mode sensor (Fig. 84) is an elec-
tronic device whose output can be interpreted to indi-
cate the shift motor shaft's rotary position. The
sensor consists of a magnetic ring and four Hall
Effect Transistors to create a 4 channel digital device
(non-contacting) whose output converts the motor
shaft position into a coded signal. The TCCM must
supply 5VDC (+/- 0.5v) to the sensor and monitor the
shift motor position. The four channels are denoted
A, B, C, and D. The sensor is mechanically linked to
the shaft of the cam which causes the transfer case
shifting. The mode sensor draws less than 53 mA.
Fig. 83 Bend Slinger Upward
1 - SEAL SLINGER
2 - BEND UPWARD
Fig. 84 Mode Sensor - Typical
1 - MODE SENSOR
21 - 538 TRANSFER CASE - NV244 GENIIDR
FRONT OUTPUT SHAFT SEAL (Continued)

SHIFT MOTOR
DESCRIPTION
The shift motor (Fig. 85) consists of a permanent
magnet D.C. motor with gear reduction to convert a
high speed-low torque device into a low speed-high
torque device. The output of the device is coupled to
a shaft which internally moves the mode and range
forks that change the transfer case operating ranges.
The motor is rated at 25 amps maximum at 72É F
with 10 volts at the motor leads.
OPERATION
The transfer case shift motor responds to the
Transfer Case Control Module (TCCM) commands to
move the transfer case shift sector bi-directionally, as
required, to obtain the transfer case operating mode
indicated by the instrument panel mounted selector
switch.
REMOVAL
NOTE: New shift motor assemblies are shipped in
the 2WD/AWD position. If a new shift motor assem-
bly will be installed, it will be necessary to shift the
transfer case to the 2WD/AWD position prior to
motor removal.
(1) Raise the vehicle on a suitable hoist.
(2) Disengage the wiring connectors from the shift
motor and mode sensor.
(3) Remove the bolts holding the shift motor and
mode sensor assembly onto the transfer case.
(4) Separate the shift motor and mode sensor
assembly from the transfer case.
INSTALLATION
(1) Verify that the shift sector o-ring is clean and
properly positioned over the shift sector and against
the transfer case.
NOTE: Verify that the shift motor position and sec-
tor shaft orientation are aligned. It may be neces-
sary to manually shift the transfer case if the shift
motor and sector shaft are not aligned.
(2) Position the shift motor and mode sensor
assembly onto the transfer case.
(3) Install the bolts to hold the assembly onto the
transfer case. Tighten the bolts to 16-24 N´m (12-18
ft.lbs.).
CAUTION: If the original shift motor and mode sen-
sor assembly bolts are reused, be sure to use
MoparTLock & Seal or LoctiteŸ 242 to replenish
the lock patch material originally found on the bolts
(4) Engage the wiring connectors to the shift motor
and mode sensor.
(5) Refill the transfer case as necessary.
(6) Lower vehicle and verify transfer case opera-
tion.
Fig. 85 Shift Motor - Shown Inverted - Typical
1 - SHIFT MOTOR
DRTRANSFER CASE - NV244 GENII 21 - 541

TRANSFER CASE - NV273
TABLE OF CONTENTS
page page
TRANSFER CASE - NV273
DESCRIPTION........................542
OPERATION..........................543
DIAGNOSIS AND TESTING - TRANSFER
CASE - NV273.......................543
REMOVAL............................544
DISASSEMBLY........................544
CLEANING...........................554
INSPECTION.........................554
ASSEMBLY...........................556
INSTALLATION........................568
SPECIFICATIONS
TRANSFER CASE - NV273.............568
SPECIAL TOOLS
TRANSFER CASE NV271/NV273.........569
EXTENSION HOUSING SEAL AND DUST BOOT
REMOVAL............................571
INSTALLATION........................571FLUID
STANDARD PROCEDURE - FLUID DRAIN AND
REFILL............................571
FRONT OUTPUT SHAFT SEAL
REMOVAL............................572
INSTALLATION........................572
MODE SENSOR
DESCRIPTION........................573
OPERATION..........................573
SELECTOR SWITCH
DESCRIPTION........................574
OPERATION..........................574
SHIFT MOTOR
DESCRIPTION........................575
OPERATION..........................575
REMOVAL............................575
INSTALLATION........................575
TRANSFER CASE - NV273
DESCRIPTION
The NV273 is an electronically controlled part-time
transfer case with a low range gear reduction system.
The NV273 has three operating ranges plus a NEU-
TRAL position. The low range system provides a gear
reduction ratio for increased low speed torque capa-
bility.
The geartrain is mounted in two aluminum case
halves attached with bolts. The mainshaft front and
rear bearings are mounted in aluminum case halves.
OPERATING RANGES
Transfer case operating ranges are:
²2WD (2-wheel drive)
²4HI (4-wheel drive)
²4LO (4-wheel drive low range)
²NEUTRAL
The 2WD range is for use on any road surface at
any time.The 4HI and 4LO ranges are for off road use only.
They are not for use on hard surface roads. The only
exception being when the road surface is wet or slip-
pery or covered by ice and snow.
The low range reduction gear system is operative
in 4LO range only. This range is for extra pulling
power in off road situations. Low range reduction
ratio is 2.72:1.
SHIFT MECHANISM
Operating ranges are selected with a dash
mounted shift selector switch. The shift selector
switch provides a input to the Transfer Case Control
Module (TCCM) to indicate the driver's desire to
change operating ranges. The TCCM 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 TCCM
decides the shift is permitted, the TCCM controls the
shift motor, mounted to the exterior of the transfer
case, to perform the shift.
21 - 542 TRANSFER CASE - NV273DR

(11) Remove range fork and hub as an assembly
(Fig. 26). Note fork position for installation reference.
(12) Remove the shift sector (Fig. 27).MAINSHAFT
(1) Remove the clutch gear (Fig. 28) from the out-
put shaft.
(2) Remove the mode hub retaining ring (Fig. 29)
from the mainshaft.
Fig. 29 Remove Mode Hub Retaining Ring
1 - MAINSHAFT
2 - MODE HUB
3 - RETAINING RING
Fig. 26 Range Fork And Hub Removal
1 - RANGE HUB
2 - RANGE FORK
Fig. 27 Remove Shift Sector
1 - SHIFT SECTOR
Fig. 28 Remove Clutch Gear
1 - OUTPUT SHAFT
2 - CLUTCH GEAR
3 - MODE HUB
DRTRANSFER CASE - NV273 21 - 551
TRANSFER CASE - NV273 (Continued)

(12) Install new bearing with Tool Handle C-4171
and Installer 8128 (Fig. 49). The bearing bore is
chamfered at the top. Install the bearing so it is
flush with the lower edge of this chamfer (Fig. 50).(13) Remove seal from oil pump with suitable pry
tool.
(14) Install new seal in oil pump with Installer
7888 (Fig. 51).
(15) Remove the rear output shaft bearing snap-
ring (Fig. 52) from the rear case half.
Fig. 52 Remove Rear Output Bearing Outer
Snap-Ring
1 - REAR CASE HALF
2 - REAR OUTPUT SHAFT BEARING
3 - SNAP-RING
Fig. 49 Install Front Output Shaft Rear Bearing
1 - REAR CASE HALF
2 - HANDLE C-4171
3 - INSTALLER 8128
Fig. 50 Output Shaft Rear Bearing Installation Depth
1 - BEARING (SEATED) AT LOWER EDGE OF CHAMFER
2 - CHAMFER
Fig. 51 Oil Pump Seal Installation
1 - HOUSING SEAL
2 - SPECIAL TOOL 7888
3 - OIL PUMP FEED HOUSING
21 - 558 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)

(5) Install the clutch gear (Fig. 65) onto the output
shaft. Verify that the pointed ends of the clutch gear
teeth are pointing to the front of the mainshaft.
(6) Lubricate sector shaft with transmission fluid
and install shift sector in case (Fig. 66). Position slot
in sector so it will be aligned with shift fork pin
when shift forks are installed.
(7) Apply LoctiteŸ 242, or equivalent, to the
threads of the sector support to replentish the factory
applied patch. Install the shift sector support.
Tighten the sector support with Socket 9033 to 27-34
N´m (20-25 ft.lbs.).(8) Assemble and install range fork and hub (Fig.
67). Be sure hub is properly seated in low range gear
and engaged to the input gear.
(9) Align and insert range fork pin in shift sector
slot.
(10) Install mode fork and shift rail onto the mode
sleeve.
(11) Install the mode fork, sleeve, and shift rail
into the transfer case (Fig. 68).
Fig. 65 Install Clutch Gear
1 - OUTPUT SHAFT
2 - CLUTCH GEAR
3 - MODE HUB
Fig. 66 Install Shift Sector
1 - SHIFT SECTOR
Fig. 67 Install Range Fork And Hub Assembly
1 - RANGE HUB
2 - RANGE FORK
Fig. 68 Mode Fork And Sleeve Installation
1 - MODE SLEEVE
2 - MODE FORK AND RAIL
21 - 562 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)

(12) Install new o-ring on detent plug (Fig. 69).
(13) Install detent plunger, spring, and plug (Fig.
70). Tighten the plug to 16-25 N´m (12-18 ft. lbs.).(1) Position the shift motor and mode sensor
assembly (Fig. 71) onto the transfer case.
(2) Install the bolts (Fig. 72) to hold the shift
motor and mode sensor assembly to the transfer
case. Tighten the bolts to 16-25 N´m (12-18 ft. lbs.).
Fig. 69 O-Ring Installation On Detent Plug
1 - O-RING
2 - DETENT PLUG
Fig. 70 Install Detent plug, Spring, and Plunger
1 - FRONT CASE HALF
2 - DETENT PLUG
3 - SPRING
4 - PLUNGER
Fig. 71 Install Shift Motor Assembly Onto Transfer
Case
1 - TRANSFER CASE
2 - SHIFT MOTOR ASSEMBLY
Fig. 72 Install Shift Motor Assembly Bolts
1 - TRANSFER CASE
2 - SHIFT MOTOR ASSEMBLY
3 - BOLTS
DRTRANSFER CASE - NV273 21 - 563
TRANSFER CASE - NV273 (Continued)