Transfer case JEEP CHEROKEE 1994 Service Workshop Manual

AW-4 AUTOMATIC TRANSMISSION
CONTENTS
page page
AW-4 IN-VEHICLE SERVICE............. 173
AW-4 TRANSMISSION DIAGNOSIS........ 167
AW-4 TRANSMISSION OVERHAUL........ 192
AW-4 TRANSMISSION REMOVAL AND
INSTALLATION....................... 189GENERAL INFORMATION................ 156
TRANSMISSION/TRANSFER CASE
SPECIFICATIONS..................... 320
GENERAL INFORMATION
INDEX
page page
Components and Operation................ 157
Description............................ 156
FirstÐThirdÐReverse Gear Components...... 159
Fourth Gear Overdrive Components......... 158
Geartrain Operation and Application Charts.... 159Hydraulic System........................ 160
Torque Converter........................ 158
Transmission Identification................. 157
Transmission Ranges and Shift Lever Positions . 157
DESCRIPTION
The AW-4 is a 4-speed, electronically controlled au-
tomatic transmission (Fig. 1). Running gear consists
of a torque converter, oil pump, three planetary gear
sets, clutch and brake units, hydraulic accumulators,
a valve body with electrical solenoids and a transmis-sion control module (TCM). The AW-4 is used in XJ
models with a 4.0L engine.
Cables are used for shifting and transmission
throttle pressure control. A park/neutral position
switch permits engine starting in Park and Neutral
range only.
Fig. 1 AW-4 Automatic Transmission
21 - 156 TRANSMISSION AND TRANSFER CASEJ

PRESSURE TEST ANALYSIS
If pressures in D and Reverse are higher than
specified, check for the following:
²throttle cable loose, worn, binding or out of adjust-
ment
²throttle valve, downshift plug, throttle cam, or pri-
mary regulator valve are sticking, worn or damaged
If pressures in D and Reverse are lower than spec-
ified, check for following:
²throttle cable loose, worn, binding or out of adjust-
ment
²throttle valve, downshift plug, throttle cam stick-
ing, worn or damaged
²primary regulator valve sticking, worn, or dam-
aged
²oil pump gears or housing worn or damaged
²overdrive clutch worn or damaged
If pressures are low in D range only, check for fol-
lowing:
²forward clutch worn or damaged
²fluid leakage in D range circuit (component seal
and O-rings)
If pressures are low in Reverse only, check for fol-
lowing:
²shift cable and manual valve out of adjustment
²fluid leakage in reverse circuit (component seal
and O-rings)
²direct clutch worn or damaged
²first/reverse brake worn or damaged
TORQUE CONVERTER STALL TEST
Stall testing checks the holding ability of the trans-
mission clutches and brakes and of the torque con-
verter stator overrunning clutch.
(1) Be sure transmission fluid is at normal operat-
ing temperature.
(2) Connect tachometer to engine. Position tachom-
eter so it can be viewed from drivers seat.
(3) Apply parking brakes and block wheels.
(4) Apply and hold service brakes.
(5) Shift transfer case into 2H position. On models
with NP249 transfer case, leave transfer case in 4H
position.
(6) Start engine.
WARNING: DO NOT ALLOW ANYONE TO STAND AT
THE FRONT OR REAR OF THE VEHICLE DURING
THE TEST.
(7) Shift transmission into D range.
(8) Press accelerator pedal to wide open throttle
position and note maximum engine rpm. Stall speed
should be 2100 to 2400 rpm in D range.
CAUTION: Do not maintain wide open throttle for
more than 3-4 seconds at a time.(9) Release throttle and shift transmission into
Neutral. Allow transmission fluid to cool for 15-20
seconds.
(10) Shift transmission into Reverse.
(11) Press accelerator down to wide open throttle
position and note maximum engine rpm. Stall speed
should be 2100-to-2400 rpm in Reverse.
STALL SPEED TEST ANALYSIS
If engine rpm is lower than specified in D and Re-
verse, check for the following:
²engine output/performance insufficient
²stator overrunning clutch in torque converter not
holding if engine speed was 1500 rpm or less.
If stall speed in D range is higher than specified,
check for the following:
²line pressure low
²forward clutch slipping
²No. 2 one-way clutch not holding
²overdrive one-way clutch not holding
If stall speed in Reverse was higher than specified,
check for the following:
²line pressure low
²direct clutch slipping
²first/ reverse brake slipping
²overdrive one-way clutch not holding
If stall speeds were higher than specified in both D
and Reverse, check for the following:
²low fluid level
²line pressure low
²overdrive one-way clutch not holding
TIME LAG TEST
This test checks general condition of the overdrive
clutch, forward clutch, rear clutch and first/reverse
brake. Condition is indicated by the amount of time
required for clutch/brake engagement with the en-
gine at curb idle speed. Engagement time is mea-
sured for D and Reverse positions. A stop watch is
recommended for test accuracy.
TEST PROCEDURE
(1) Check and adjust transmission fluid level if
necessary.
(2) Bring transmission to normal operating tem-
perature.
(3) Apply parking brakes and turn off air condi-
tioning unit.
(4) Shift transfer case into 2H range. On models
with NP249 transfer case, leave transfer case in 4H
range.
(5) Start engine and check curb idle speed. Adjust
speed if necessary. Curb idle must be correct to en-
sure accurate test results.
(6) Shift transmission into Neutral and set stop
watch.
(7) During following test steps, start stop watch as
soon as shift lever reaches D and Reverse ranges.
JAW-4 TRANSMISSION DIAGNOSIS 21 - 169

(8) Install park rod and bracket (Fig. 33). Tighten
bracket bolts to 10 Nzm (7 ft. lbs.) torque.
(9) Install valve body, oil screen and oil pan as out-
lined in this section.
ADAPTER HOUSING SEAL REPLACEMENT
(1) Raise vehicle.
(2) Disconnect or remove components necessary to
gain access to seal (e.g. propeller shaft, crossmember,
shift linkage, transfer case, exhaust components,
hoses, wires).
(3) Remove dust shield and remove seal from
adapter housing (Fig. 36).
(4) Install new seal with appropriate size seal in-
staller and install dust shield.(5) Reinstall components removed to gain access to
seal.
(6) Top off transmission fluid if necessary.SPEED SENSOR
SPEED SENSOR TESTING
Test the speed sensor with an ohmmeter. Place the
ohmmeter leads on the terminals in the sensor con-
nector (Fig. 37).
Rotate the transmission output shaft and observe
the ohmmeter needle. The needle should deflect indi-
cating the switch is opening/closing as the rotor
Fig. 34 Removing/Installing Park Rod
Fig. 35 Removing/Installing Park Pawl, Pin And
Spring
Fig. 32 Second Coast Brake Servo Components
Fig. 33 Removing/Installing Park Rod Bracket
21 - 182 AW-4 IN-VEHICLE SERVICEJ

moves past the sensor (Fig. 37). Replace the sensor if
the ohmmeter does not display any kind of reading.
If a digital ohmmeter is being used, the sensor
should generate an ohmmeter readout each time the
switch opens and closes.
SPEED SENSOR REPLACEMENT
(1) Disconnect sensor wire harness connector.
(2) Remove sensor retainer bolt and remove sensor
(Fig. 38).
(3) Remove and discard speed sensor O-ring.(4) Install new O-ring on speed sensor and install
sensor in transmission case.
(5) Install sensor bracket and retainer bolt.
Tighten bolt to 7.4 Nzm (65 in. lbs.) torque.
(6) Connect sensor wire harness connector.
SPEED SENSOR ROTORÐSPEEDOMETER DRIVE
GEAR
ROTORÐDRIVE GEAR REMOVAL
(1) Raise vehicle.
(2) Remove components necessary to gain access to
rotor and drive gear such as propeller shaft, transfer
case, crossmember, and shift linkage.
(3) Disconnect speedometer cable and/or speed sen-
sor.
(4) Remove adaptor housing.
(5) Remove speedometer drive gear snap ring (Fig.
39).
(6) Remove the speedometer drive gear and spacer
(if equipped).
(7) Remove rotor by carefully prying it off output
shaft with wood dowel or hammer handle (Fig. 40).
(8) Clean sealing surfaces of transmission case and
extension/adaptor housing.
ROTOR AND DRIVE GEAR INSTALLATION
(1) Install rotor, spacer (if equipped) and drive gear
on output shaft. Then install drive gear snap ring
(Fig. 39).
(2) Apply bead of Mopar or Loctite 599 sealer, to
transmission case sealing surface and install exten-
sion/adapter housing on case.
Fig. 36 Adapter Housing Seals
Fig. 37 Speed Sensor Testing
Fig. 38 Transmission Speed Sensor Removal/
Installation
JAW-4 IN-VEHICLE SERVICE 21 - 183

AW-4 TRANSMISSION REMOVAL AND INSTALLATION
INDEX
page page
Oil Pump Seal Replacement............... 189
Torque Converter Stator Clutch Inspection..... 189Transmission and Torque Converter Installation . 190
Transmission and Torque Converter Removal . . 189
TRANSMISSION AND TORQUE CONVERTER
REMOVAL
(1) Raise vehicle.
(2) Drain transmission fluid and reinstall oil pan
drain plug.
(3) Remove upper half of transmission fill tube
(Fig. 50).
(4) Disconnect cooler lines at transmission. Cooler
lines have quick-disconnect fittings. Press fitting re-
lease tabs and pull cooler lines and fittings out of
case or use Special Tool 7555 to disconnect them.
(5) Support engine with safety stand and support
transmission with jack.
(6) Disconnect transmission and transfer case shift
linkage.
(7) Remove necessary exhaust components.
(8) Disconnect vehicle speed sensor wires
(9) Mark position of front and rear propeller shafts
for alignment reference. Then remove shafts from ve-
hicle.
(10) Remove rear crossmember.
(11) Disconnect transmission shift cable at trans-
mission. Then disconnect transmission throttle valve
cable at engine.(12) Disconnect necessary vacuum and fluid hoses.
(13) Remove transfer case from transmission.
(14) Disconnect and remove crankshaft position
sensor.
CAUTION: The crankshaft position sensor can be
damaged if the sensor is still in place when the
transmission is removed. To avoid damage, remove
the sensor before transmission removal.
(15) Remove starter motor.
(16) Remove bolts attaching converter to drive
plate.
(17) Remove bolts attaching converter housing to
engine.
(18) Secure transmission to jack with safety
chains.
(19) Pull transmission rearward for access to con-
verter. Then secure converter in pump with C-clamp
or strap bolted to converter housing.
(20) Remove transmission from under vehicle.
(21) Remove torque converter if converter or oil
pump seal are to be serviced.
TORQUE CONVERTER STATOR CLUTCH
INSPECTION
(1) Insert Rotating Tool 7547 into converter hub
and seat tool in one-way clutch (Fig. 51).
(2) Insert Stopper Tool 7548 in one converter hub
notch and into outer race of rotating tool.
(3) Turn rotating tool clockwise. Converter clutch
should rotate freely and smoothly. Less than 2.5 Nzm
(22 in. lbs.) of torque should be required to rotate
clutch in clockwise direction.
(4) Turn rotating tool in counterclockwise direction.
Converter clutch should lock.
(5)
Replace converter if clutch binds or will not lock.
OIL PUMP SEAL REPLACEMENT
(1) Remove converter.
(2) Remove old seal. Use blunt punch to collapse
seal and pry seal out of pump housing. Do not
scratch or damage seal bore.
(3) Lubricate lip of new seal with Mopar Mercon
transmission fluid and install seal in pump with tool
7549 (Fig. 52).
(4) Lubricate converter drive hub with Mopar Mer-
con transmission fluid.
Fig. 50 Two-Piece Transmission Fill Tube
JAW-4 TRANSMISSION REMOVAL AND INSTALLATION 21 - 189

(5) Align and install converter in oil pump.
TRANSMISSION AND TORQUE CONVERTER
INSTALLATION
(1) Mount transmission on transmission jack. Then
secure transmission to jack with safety chains.
(2) Lubricate converter drive hub and oil pump
seal lip with Mopar Mercon transmission fluid. Then
install converter. Be sure converter is fully seated in
oil pump gears before proceeding. Hold converter in
place with C-clamp or strap attached to converter
housing.
(3) Align and position transmission and converter
on engine.
(4) Remove clamp or strap used to hold torque con-
verter in place.
(5) Move transmission forward seat and it on en-
gine. Be sure torque converter hub is fully seated.
(6)
Install converter housing-to-engine bolts (Fig.
53).
(7) Install converter-to-drive plate bolts.
(8) Install and connect starter motor.
(9) Install and connect crankshaft position sensor.
(10) Install transfer case on transmission. Tighten
transfer case attaching nuts to 41 Nzm (30 ft. lbs.)
torque
(11) Connect transfer case shift linkage and vac-
uum hoses.
(12) Connect exhaust components.
(13) Install rear crossmember and remove jack
used to support transmission assembly.
(14) Connect speed sensor wire harness to sensor.
(15) Connect wire harness to park/neutral position
switch.
(16) Align and connect front and rear propeller
shafts.
Fig. 51 Checking Operation Of Torque Converter
Stator One-Way Clutch
Fig. 52 Installing Oil Pump Seal
21 - 190 AW-4 TRANSMISSION REMOVAL AND INSTALLATIONJ

(17) Connect transmission wire harnesses and
transfer case vacuum and wire harnesses.
(18) Connect transmission cooler lines.
(19) Connect transmission throttle cable at engine.(20) Install new O-ring seal on upper half of trans-
mission fill tube. Then connect upper and lower tube
halves.
(21) Lower vehicle.
(22) Fill transmission with Mopar Mercon auto-
matic transmission fluid. Mopar Dexron II can be
used if Mercon is not readily available.
Fig. 53 AW-4 Transmission Attachment
JAW-4 TRANSMISSION REMOVAL AND INSTALLATION 21 - 191

NP231 TRANSFER CASE
INDEX
page page
General Information...................... 272
Shift Linkage Adjustment.................. 275
Speedometer Service.................... 275
Transfer Case Assembly.................. 282
Transfer Case Disassembly and Overhaul..... 277Transfer Case Identification................ 273
Transfer Case Installation................. 276
Transfer Case Lubricant.................. 273
Transfer Case Removal................... 276
GENERAL INFORMATION
The NP231 is a part-time transfer case with a low
range reduction gear system (Fig. 1). The NP231 has
three operating ranges plus a Neutral position. A low
range system provides a reduction ratio for increased
low speed torque capability.The NP231 is the Command Trac transfer case. It
is used in XJ and YJ models.
Two versions of the NP231 are used. One version
retains the synchronizer components used in previ-
ous models. A newly introduced version is not
equipped with synchro components.
Fig. 1 NP231 Transfer Case
21 - 272 NP231 TRANSFER CASEJ

OPERATING RANGES
NP231 operating ranges are: 2-wheel drive high; 4-
wheel drive high and 4-wheel drive low (Fig. 2).
2-wheel drive range is for use on all surfaces. The
4-wheel drive high and low ranges are undifferenti-
ated and should only be used on unpaved, low trac-
tion surfaces only.
SHIFT MECHANISM
Operating ranges are selected with a floor mounted
shift lever. The shift lever is connected to the trans-
fer case range lever by an adjustable linkage rod. A
straight line shift pattern is used (Fig. 2). Range po-
sitions are marked on the shifter bezel cover plate. A
front axle disconnect mechanism is only used on cer-
tain models.
TRANSFER CASE IDENTIFICATION
A circular ID tag is attached to the rear case of
each NP231 transfer case (Fig. 3). The ID tag pro-vides the transfer case model number, assembly
number, serial number and low range ratio.
The transfer case serial number also represents the
date of build. For example, a serial number of 8-
10-92 would represent August 10, 1992.
TRANSFER CASE LUBRICANT
Recommended Lubricant
Use Mopar Dexron II, or ATF Plus, type 7176 au-
tomatic transmission fluid in the NP231 transfer
case.
Lubricant Capacity
Approximate refill lubricant capacity is 1.54 liters
(3.25 pints) for YJ and 1.04 liters (2.2 pints) for XJ.
Fill Level
The correct fill level is to the bottom edge of the fill
plug hole. The vehicle must be level in order to en-
sure an accurate fluid level check.
Fig. 2 NP231 Shift Pattern
Fig. 3 Transfer Case Identification Tag
JNP231 TRANSFER CASE 21 - 273

NP231 SERVICE DIAGNOSIS
21 - 274 NP231 TRANSFER CASEJ