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TRANSFER CASE - NV243 - SERVICE
INFORMATION
DESCRIPTION ............................. 1657
OPERATION ............................... 1657
DIAGNOSIS AND TESTING - TRANSFER
CASE - NV243 ............................ 1658
REMOVAL ................................. 1659
DISASSEMBLY ............................. 1659
CLEANING ................................. 1671
INSPECTION ............................... 1671
ASSEMBLY . ............................... 1674
INSTALLATION ............................. 1686
SPECIFICATIONS
TRANSFER CASE - NV243 ................ 1686
SPECIAL TOOLS
TRANSFER CASE - NV243 ................ 1687
SEAL-EXTENSION HOUSING
REMOVAL ................................. 1689
INSTALLATION ............................. 1689
FLUID
STANDARD PROCEDURE - FLUID DRAIN AND
REFILL ................................... 1690SEAL-FRONT OUTPUT SHAFT
REMOVAL ................................. 1691
INSTALLATION ............................. 1692
SENSOR-MODE
DESCRIPTION ............................. 1693
OPERATION ............................... 1693
SWITCH-SELECTOR
DESCRIPTION ............................. 1695
OPERATION ............................... 1695
MOTOR-SHIFT
DESCRIPTION ............................. 1697
OPERATION ............................... 1697
REMOVAL ................................. 1697
INSTALLATION ............................. 1697
ASSEMBLY-SHIFT MOTOR/MODE SENSOR
DESCRIPTION ............................. 1699
OPERATION ............................... 1699
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TRANSFER CASE - NV243 - SERVICE INFORMATION
DESCRIPTION
The NV243 is an electronically controlled part-time transfer case with a low range gear reduction system. The
NV243 has three operating ranges plus a NEUTRAL position. The low range system provides a gear reduction ratio
for increased low speed torque capability.
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.
OPERATING RANGES
Transfer case operating ranges are:
2WD (2-wheel drive).
4HI (4-wheel drive).
4LO (4-wheel drive low range).
NEUTRAL.
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 slippery 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 desireto 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.
IDENTIFICATION
A circular ID tag (1) is attached to the rear case of
each transfer case. The ID tag provides the transfer
case model number, assembly number, serial number,
and low range ratio.
The transfer case serial number also represents the
date of build.
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 themodefork,whichoperatesthemode
sleeve and hub. The sleeve and hub are not equipped with a synchronizer mechanism for shifting.
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DIAGNOSIS AND TESTING - TRANSFER CASE - NV243
DIAGNOSIS CHART
Condition Possible Cause Correction
Transfer case difficult to shift or will
not shift into desired range.1) Transfer case electronically
controlled shift system malfunction.1) Verify proper operation per the
appropriate diagnostic manual.
2) If vehicle was operated for an
extended period in 4HI mode on dry
surface, driveline torque load may
cause difficulty.2) Drive the vehicle in a straight line
and momentarily release the
accelerator. The transfer case can
then be shifted to the desired mode.
3) Insufficient or incorrect lubricant. 3) Drain and refill transfer casewith
the correct quantity of Mopar
AT F
+4, Automatic Transmission Fluid.
4) Internal transfer case
components binding, worn, or
damaged.4) Repair or replace components as
necessary.
Transfer case noisy in all drive
modes.1) Insufficient or incorrect lubricant. 1) Drain and refill transfer casewith
the correct quantity of Mopar
AT F
+4, type 9602, Automatic
Transmission Fluid.
2) Internal transfer case
components binding, worn, or
damaged.2) Repair or replace components as
necessary.
Transfer case noisy while in, or
jumps out of, 4LO mode.1) Transfer case not completely
engaged in 4LO position.1) While rolling 2-3 MPH and the
transmission in NEUTRAL, or clutch
depressed on vehicles equipped
with a manual transmission, shift
transfer case to the 2WD or 4HI
position, and then back into the 4LO
position.
2) Range fork damaged, inserts
worn, or fork is binding on the shift
rail.2) Repair or replace components as
necessary.
3) Low range gear worn or
damaged.3) Repair or replace components as
necessary.
Lubricant leaking from transfer case
seals or vent.1) Transfer case overfilled. 1) Drain lubricant to the correct
level.
2) Transfer case vent closed or
restricted.2) Clean or replace vent as
necessary.
3) Transfer case seals damaged or
installed incorrectly.3) Replace suspect seal.
Abnormal tire wear. 1) Extended operation in 4HI mode
on dry surfaces,1) Operate vehicle in 2WD mode on
dry surfaces.
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REMOVAL
1. Shift transfer case into 2WD.
2. Raise vehicle.
3. Drain transfer case lubricant.
4. Mark front and rear propeller shafts for alignment
reference.
5. Support transmission with jack stand.
6. Remove the transfer case skid plate, if equipped.
7. Disconnect front and rear propeller shafts at trans-
fer case.
8. Disconnect transfer case shift motor and mode
sensor wire connectors (3).
9. Disconnect transfer case vent hose.
10. Support transfer case with transmission jack.
11. Secure transfer case to jack with chains.
12. Remove nuts attaching transfer case (2) to transmission (1).
13. Pull transfer case and jack rearward to disengage transfer case.
14. Remove transfer case from under vehicle.
DISASSEMBLY
Position transfer case in a shallow drain pan. Remove drain plug and drain any remaining lubricant remaining in
case.
SHIFT MOTOR ASSEMBLY AND FRONT OUTPUT SHAFT SEAL
1. Remove the bolts (3) which hold the shift motor
and mode sensor assembly (2) to the transfer case
(1).
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2. Remove the shift motor and mode sensor assem-
bly from the transfer case.
3. Remove the front propeller shaft seal boot (1)
retaining clamp (2).
4. Remove the front propeller shaft seal boot (1).
5. Remove the front output shaft seal slinger (1) by
bending (2) the slinger ears away from the transfer
case.
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6. Using a suitable pry tool (2), remove the slinger (1)
from the output shaft using care not to damage the
shaft.
7. Using a screw and a slide hammer, remove the
front output shaft seal.
REAR EXTENSION
1. Remove rear extension bolts (1).
2. Remove rear extension housing (1). Tap extension
once or twice with a plastic mallet to break sealer
bead and loosen it.
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3. Remove output bearing (2) retaining ring (3) with
heavy duty snap-ring pliers.
OIL PUMP AND REAR CASE
1. Remove rear case (1)-to-front case (2) bolts (3).
2. Loosen rear case (1) with pry tool to break sealer
bead. Insert tool in slot (3) at each end of case.
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3. Unseat rear case from alignment dowels.
4. Remove rear case (1) and oil pump assembly from
front case (2).
CAUTION: Do not remove the bolts holding the oil
pump cover to the rear case half. The oil pump
cover is aligned to the rear output shaft inner
bearing race and will become mis-aligned if the
bolts are loosened. If the transfer case failure has
generated any debris which may have become
trapped in the oil pump. the rear case and oil
pump assembly MUST be replaced.
5. Remove the oil pump pickup tube.
FRONT OUTPUT SHAFT AND DRIVE CHAIN
1. Remove shift rail cup (3) and spring (2).
2. Remove front sprocket (1) retaining ring (2).