CONVERTER STALL TEST
Stall testing involves determining maximum engine
rpm obtainable at full throttle with the rear wheels
locked and the transmission in D range. This test
checks the holding ability of the converter overrun-
ning clutch and both of the transmission clutches.
When stall testing is completed, refer to the Stall
Speed Specifications chart and Stall Speed Diagnosis
guides.
WARNING: NEVER ALLOW ANYONE TO STAND IN
FRONT OF THE VEHICLE DURING A STALL TEST.
ALWAYS BLOCK THE FRONT WHEELS AND APPLY
THE SERVICE AND PARKING BRAKES DURING
THE TEST.
STALL TEST PROCEDURE
(1) Connect tachometer to engine.
(2) Check and adjust transmission fluid level.
(3) Start and run engine until transmission fluid
reaches normal operating temperature.
(4) Block front wheels.
(5) Fully apply service and parking brakes.
(6) Open throttle completely and record maximum
engine rpm registered on tachometer. It will take
from 3 to 10 seconds to reach maximum rpm. How-
ever, once maximum rpm has been achieved,do not
hold wide open throttle for more than 5 sec-
onds.
CAUTION: Stalling the converter causes a rapid in-
crease in fluid temperature. To avoid fluid overheat-
ing, hold wide open throttle for no more than 5
seconds after reaching peak rpm. In addition, if
more than one stall test is required, run the engine
at 1000 rpm with the transmission in Neutral for at
least 20 seconds to cool the fluid.
(7) Stall speeds should be in 1700-2150 rpm range.
CAUTION: If engine exceeds 2150 rpm, release ac-
celerator pedal immediately as transmission clutch
slippage is occurring.
(8) Shift transmission into Neutral. Run engine for
20-30 seconds at 1000 rpm to cool fluid. Then stop
engine, shift transmission into Park and release
brakes.
(9) Refer to Stall Test Diagnosis.
STALL TEST DIAGNOSIS
Stall Speed Too Low
Low stall speeds with a properly tuned engine in-
dicate a torque converter overrunning clutch prob-
lem. The condition should be confirmed by road
testing prior to converter replacement.The converter overrunning clutch is slipping when
stall speeds are 250 to 350 rpm below specified min-
imum.
A converter overrunning clutch failure will result
in sluggish acceleration in all speed ranges. It will
also require greater than normal throttle opening to
maintain cruising speeds.
Stall Speed Too High
If stall speed exceeds 2150 rpm, transmission
clutch slippage is occurring.
Stall Speed Normal But Acceleration Is Sluggish
If stall speeds are within specified range but abnor-
mal throttle opening is required for acceleration, or
to maintain cruise speeds, the converter overrunning
clutch is seized. The torque converter will have to be
replaced.
Converter Noise During Test
A whining noise caused by fluid flow is normal dur-
ing a stall test. However, loud metallic noises indi-
cate a damaged converter. To confirm that noise is
originating from the converter, operate the vehicle at
light throttle in Drive and Neutral on a hoist and lis-
ten for noise from the converter housing.
AIR PRESSURE TEST
Air pressure testing can be used to check clutch
and band operation with the transmission either in
the vehicle, or on the work bench as a final check af-
ter overhaul.
Air pressure testing requires that the oil pan and
valve body be removed from the transmission.
The servo and clutch apply passages are shown in
Figure 8.
Air Test Procedure
(1) Place one or two fingers on the clutch housing
and apply air pressure through front clutch apply
passage (Fig. 8). Piston movement can be felt and a
soft thud heard as the clutch applies.
(2) Place one or two fingers on the clutch housing
and apply air pressure through rear clutch apply
passage (Fig. 8). Piston movement can be felt and a
soft thud heard as the clutch applies.
(3) Apply air pressure to the front servo apply pas-
sage. The servo rod should extend and cause the
band to tighten around the drum. Spring tension
should release the servo when air pressure is re-
moved.
(4) Apply air pressure to the rear servo apply pas-
sage. The servo rod should extend and cause the
band to tighten around the drum. Spring tension
should release the servo when air pressure is re-
moved.
21 - 74 30RH/32RH TRANSMISSION DIAGNOSISJ
PRESSURE TEST ANALYSIS
If pressures in D and Reverse are higher than
specified in test, 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 in test, check for following:
²throttle cable loose, worn, binding or out of adjust-
ment
²throttle valve, downshift plug, or throttle cam
sticking, 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.Stall speeds are
checked in both Drive and Reverse ranges with
the AW-4 transmission.
(1) Before starting test, be sure fluid level is cor-
rect and fluid is at normal operating 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.
(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) Open throttle completely and record maximum
engine rpm registered on tachometer. It takes any-
where from 4 to 10 seconds to reach maximum rpm.
However, once maximum rpm has been achieved,do
not hold wide open throttle for more than 3-4
seconds.CAUTION: Stalling the converter causes a rapid in-
crease in fluid temperature. To avoid fluid overheat-
ing, hold wide open throttle for no more than 4
seconds after reaching peak rpm. In addition, if
more than one stall test is required, run the engine
at 1000 rpm with the transmission in Neutral for at
least 20 seconds to cool the fluid.
(9) Stall speed should be in 2100-2400 rpm range
in Drive.
(10) Release throttle, shift transmission into Neu-
tral, and run engine for 20-30 seconds to cool fluid.
(11) Shift transmission into Reverse.
(12) Repeat stall test described in step (8).
(13) Stall speed in Reverse should also be in 2100-
2400 rpm range.
(14) Release accelerator pedal, shift transmission
into Neutral, and run engine for 20-30 seconds to
cool fluid.
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.
21 - 178 AW-4 TRANSMISSION DIAGNOSISJ
NP242 TRANSFER CASE
INDEX
page page
General Information....................... 307
Operating Ranges........................ 307
Overhaul Cleaning and Inspection............ 318
Recommended Lubricant/Capacity/Fill Level..... 307
Shift Lever Installation (XJ)................. 309
Shift Lever Removal (XJ)................... 309
Shift Linkage Adjustment................... 309
Shift Mechanism......................... 307Speedometer Service..................... 309
Transfer Case Assembly................... 319
Transfer Case Changes.................... 307
Transfer Case Disassembly and Overhaul...... 310
Transfer Case Identification................. 307
Transfer Case Installation.................. 309
Transfer Case Removal.................... 309
GENERAL INFORMATION
The NP242 is a full and part-time transfer case
(Fig. 1). It provides full time 2-wheel, or 4-wheel
drive operation. The NP242 is used in XJ models.
A differential in the transfer case is used to control
torque transfer to the front and rear axles. A low
range gear provides increased low speed torque capa-
bility for off road operation. The low range provides a
2.72:1 reduction ratio.
OPERATING RANGES
NP242 operating ranges are 2WD (2-wheel drive),
4x4 part-time, 4x4 full time, and 4 Lo.
The 2WD and 4x4 full time ranges can be used at
any time and on any road surface.
The 4x4 part-time and 4 Lo ranges are for off road use
only. The only time these ranges can be used on hard sur-
face roads, is when the surface is covered with snow and
ice.
SHIFT MECHANISM
Transfer case 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. Range po-
sitions are marked on the shift knob or shifter bezel plate.
TRANSFER CASE IDENTIFICATION
A circular I.D. tag is attached to the rear case of
each NP242 transfer case (Fig. 2). The 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. For example, a serial number of
1-10-94 would represent January 10, 1994.
RECOMMENDED LUBRICANT/CAPACITY/FILL LEVEL
Mopar Dexron II is the recommended fluid for the
NP242 transfer case. Approximate dry fill lubricant
capacity is 1.4 liters (1.48 qts.).
Correct transfer case lubricant level is to the bot-
tom edge of the fill plug hole.
TRANSFER CASE CHANGES
The only service change for 1995 involves the front
output shaft seal which is new. The new seal does
not have the flange used on prior seals and changes
seal installation. The new seal must be seated below
the edge of the seal bore in the front case. Refer to
the overhaul information for seal installation.
Fig. 1 NP242 Transfer Case
Fig. 2 Transfer Case I.D. Tag
JNP242 TRANSFER CASE 21 - 307
WHEELS
GENERAL INFORMATION
Original equipment wheels are designed for the
specified Maximum Vehicle Capacity.
All models use steel or cast aluminum drop center
wheels. The safety rim wheel (Fig. 1) has raised sec-
tions between the rim flanges and the rim well.
Initial inflation of the tire forces the bead over
these raised sections. In case of tire failure, the
raised sections hold the tire in position on the wheel
until the vehicle can be brought to a safe stop.
Cast aluminum wheels require special balance
weights and alignment equipment.
WHEEL INSTALLATION
The wheel studs and nuts are designed for specific
applications. They must be replaced with equivalent
parts. Do not use replacement parts of lesser quality
or a substitute design. All aluminum and some steel
wheels have wheel stud nuts which feature an en-
larged nose. This enlarged nose is necessary to en-
sure proper retention of the aluminum wheels.
Before installing the wheel, be sure to remove any
build up of corrosion on the wheel mounting surfaces.
Ensure wheels are installed with good metal-to-metal
contact. Improper installation could cause loosening
of wheel nuts. This could affect the safety and han-
dling of your vehicle.
To install the wheel, first position it properly on
the mounting surface. All wheel nuts should then be
tightened just snug. Gradually tighten them in se-
quence to 129 Nzm (95 ft. lbs.) torque (Fig. 2).Never
use oil or grease on studs or nuts.
WHEEL REPLACEMENT
Wheels must be replaced if they have:²Excessive runout
²Bent or dented
²Leak air through welds
²Have damaged bolt holes
Wheel repairs employing hammering, heating, or
welding are not allowed.
Original equipment wheels are available through
your dealer. Replacement wheels from any other
source should be equivalent in:
²Load carrying capacity
²Diameter
²Width
²Offset
²Mounting configuration
Failure to use equivalent replacement wheels may
affect the safety and handling of your vehicle. Re-
placement withusedwheels is not recommended.
Their service history may have included severe treat-
ment.
Refer to the Specifications Chart for informa-
tion regarding above requirements.
WHEEL ORNAMENTATION
WARNING: HANDLE ALL WHEEL ORNAMENTATION
WITH EXTREME CARE DURING REMOVAL AND IN-
STALLATION. SHARP EDGES ON THE COVERS OR
CAPS CAN CAUSE PERSONAL INJURY.
TIRE AND WHEEL BALANCE
It is recommended that a two plane dynamic bal-
ancer be used when a wheel and tire assembly re-
quire balancing. Static should be used only when a
two plane balancer is not available.
For static imbalance, find location of heavy spot
causing imbalance. Counter balance wheel directly
Fig. 1 Wheel Safety Rim
Fig. 2 Lug Nut Tightening Pattern
22 - 6 WHEELS AND TIRESJ
Drive vehicle a short distance to eliminate tire flat
spotting from a parked position.
Make sure all wheel nuts are properly torqued.
Relocate wheel on the mounting, two studs over
from the original position.
Re-tighten wheel nuts until all are properly
torqued, to eliminate brake distortion.
Check radial runout. If still excessive, mark tire
sidewall, wheel, and stud at point of maximum
runout and proceed to Method 2.
METHOD 2 (RELOCATE TIRE ON WHEEL)
Rotating tire on wheel is particularly effective
when there is runout in both tire and wheel.Remove tire from wheel and re-mount wheel on
hub in former position.
Check wheel radial runout (Fig. 9).
²STEEL WHEELS: Radial runout 0.040 in., Lateral
runout 0.045 in.
²ALUMINUM WHEELS: Radial runout 0.030 in.,
Lateral runout 0.035 in.
If point of greatest runout is near original chalk
mark, remount tire 180 degrees. Recheck runout.
Fig. 8 Checking Tire Runout
Fig. 9 Checking Wheel Runout
JWHEELS AND TIRES 22 - 9
VEHICLE VIBRATION
Vehicle vibration can be caused by:
²Tire/wheel unbalance or excessive runout
²Defective tires with extreme tread wear
²Nylon overlay flat spots (performance tires only)
²Incorrect wheel bearing adjustment (if applicable)
²Loose or worn suspension/steering components
²Certain tire tread patterns
²Incorrect drive shaft angles or excessive drive
shaft/yoke runout
²Defective or worn U-joints
²Excessive brake rotor or drum runout
²Loose engine or transmission supports/mounts
²And by engine operated accessories
Refer to the appropriate Groups in this man-
ual for additional information.
VIBRATION TYPES
There are two types of vehicle vibration:
²Mechanical
²Audible.
Mechanical vehicle vibration can be felt through
the seats, floor pan and/or steering wheel.
Audible vehicle vibration is heard above normal
background noise. The sound can be a droning or
drumming noise.
Vibrations are sensitive to change in engine torque,
vehicle speed or engine speed.
ENGINE TORQUE SENSITIVE VIBRATION
This vibration can be increased or decreased by:
²Accelerating
²Decelerating
²Coasting
²Maintaining a constant vehicle speed
VEHICLE SPEED SENSITIVE VIBRATION
This vibration condition always occurs at the same
vehicle speed regardless of the engine torque or en-
gine speed.
ENGINE SPEED (RPM) SENSITIVE VIBRATION
This vibration occurs at varying engine speeds. It
can be isolated by increasing or decreasing the en-
gine speed with the transmission in NEUTRAL posi-
tion.
VIBRATION DIAGNOSIS
A vibration diagnosis should always begin with a
10 mile (16 km) trip (to warm the vehicle and tires).
Then a road test to identify the vibration. Corrective
action should not be attempted until the vibration
type has been identified via a road test.
During the road test, drive the vehicle on a smooth
surface. If vibration exists, note and record the fol-
lowing information:²Identify the vehicle speed range when the vibra-
tion occurs
²Identify the type of vibration
²Identify the vibration sensitivity
²Determine if the vibration is affected by changes
in vehicle speed, engine speed and engine torque.
When the vibration has been identified, refer to the
Vibration Diagnosis chart for causes. Consider cor-
recting only those causes coded in the chart that are
related to the vibration condition.
Refer to the following cause codes and descriptions
for explanations when referring to the chart.
TRRÐTire and Wheel Radial Runout:Vehicle
speed sensitive, mechanical vibration. The runout
will not cause vibration below 20 mph (32 km/h).
WHÐWheel Hop:Vehicle speed sensitive, me-
chanical vibration. The wheel hop generates rapid
up-down movement in the steering wheel. The vibra-
tion is most noticeable in the 20 - 40 mph (32 - 64
km/h) range. The wheel hop will not cause vibration
below 20 mph (32 km/h). Wheel hop is caused by a
tire/wheel that has a radial runout of more than
0.045 of-an-inch (1.14 mm). If wheel runout is accept-
able and combined runout cannot be reduced by re-
positioning the tire on wheel, replace tire.
TBÐTire/Wheel Balance:Vehicle speed sensitive,
mechanical vibration. Static tire/wheel unbalance
will not cause vibration below 30 mph (46 km/h). Dy-
namic tire/wheel unbalance will not cause vibration
below 40 mph (64 km/h).
TLRÐTire/Wheel Lateral runout:Vehicle speed
sensitive, mechanical vibration. The runout will not
cause vibration below 50 - 55 mph (80 - 88 km/h). Ex-
cessive lateral runout will also cause front-end
shimmy.
TWÐTire Wear:Vehicle speed sensitive, audible
vibration. Abnormal tire wear causes small vibration
in the 30 - 55 mph (88 km/h) range. This will pro-
duce a whine noise at high speed. The whine will
change to a growl noise when the speed is reduced.
WÐTire Waddle:Vehicle speed sensitive, mechan-
ical vibration. Irregular tire uniformity can cause
side-to-side motion during speeds up to 15 mph (24
km/h). If the motion is excessive, identify the defec-
tive tire and replace it.
UAJÐUniversal Joint (Drive Shaft) Angles:
Torque/vehicle speed sensitive, mechanical/audible vi-
bration. Incorrect drive shaft angles cause mechani-
cal vibration below 20 mph (32 km/h) and in the 70
mph (112 km/h) range. The incorrect angles can also
produce an audible vibration in the 20 - 50 mph (32 -
80 km/h) range. Caster adjustment could be required
to correct the angles.
UJÐUniversal Joints:Engine torque/vehicle
speed sensitive, mechanical/audible vibration. If the
22 - 10 WHEELS AND TIRESJ
U-joint is worn it will cause vibration with almost
any vehicle speed/engine torque condition.
DSYÐDrive Shaft and Yokes:Vehicle speed sen-
sitive, mechanical/audible vibration. The condition
will not cause vibration below 35 mph (56 km/h). Ex-
cessive runout, unbalance or dents and bends in the
shaft will cause the vibration. Identify the actual
cause and repair/replace as necessary.
WBÐWheel Bearings:Vehicle speed sensitive,
mechanical/audible vibration. Loose wheel bearings
cause shimmy-like vibration at 35 mph (56 km/h)
and above. Worn bearings will also produce a growl
noise at low vehicle speed and a whine noise at high
vehicle speed. The wheel bearings must be adjusted
or replaced, as applicable.
ANÐAxle Noise:Engine torque/vehicle speed sen-
sitive, mechanical/audible vibration. The axle will not
cause mechanical vibration unless the axle shaft is
bent. Worn or damaged axle pinion shaft or differen-
tial gears and bearings will cause noise. Replace the
defective component(s) as necessary.
SSCÐSuspension and Steering Components:
Vehicle speed sensitive, mechanical vibration. Worn
suspension/steering components can cause mechani-
cal vibration at speeds above 20 mph (32 km/h).
Identify and repair or replace the defective compo-
nent(s).EAÐEngine Driven Accessories:Engine speed
sensitive, mechanical/audible vibration. Vibration can
be caused by loose or broken A/C compressor, PS
pump, water pump, generator or brackets, etc. Usu-
ally more noticeable when the transmission is shifted
into the NEUTRAL position and the engine speed
(rpm) increased. Inspect the engine driven accesso-
ries in the engine compartment. Repair/replace as
necessary.
ADBÐAccessory Drive Belts:Engine speed sen-
sitive, audible vibration. Worn drive belts can cause a
vibration that produces either a droning, fluttering or
rumbling noise. Inspect the drive belt(s) and tighten/
replace as necessary.
DEMÐDamaged Engine or Transmission Sup-
port Mounts:Engine speed sensitive, mechanical/
audible vibration. If a support mount is worn, noise
or vibration will occur. Inspect the support mounts
and repair/replace as necessary.
ESÐExhaust System:Engine speed sensitive,
mechanical/audible vibration. If loose exhaust compo-
nents contact the vehicle body they will cause noise
and vibration. Inspect the exhaust system for loose,
broken and mis-aligned components and repair/re-
place as necessary.
VIBRATION DIAGNOSIS
JWHEELS AND TIRES 22 - 11
²Install the retainers to attach the fender liner to
the fender inner panel.
²Install the rivets to attach the flare to the air de-
flector (Figs. 48 and 50). and
²Install the screws to attach the flare to the fender.
Tighten the screws to 1 Nzm (13 in-lbs) torque.
(8) Connect the front lamp wire harness connectors
to the engine wire harness connectors (Fig. 52).
(9) Install the front lamps.
(10) Install the front bumper.
(11) Install the wheel, remove the support and
lower the vehicle.
(12) Right fender only: install the hood support rod
on the fender inner panel.
(13) Install the hood bumper on the fender inner
panel.(14) Right fender only: install the Daytime Run-
ning Light (DRL) module on fender inner panel.
(15) Right fender only: install the A/C Receiver/
Drier on the fender inner panel.
(16) Right fender only: install the vapor canister
on the fender inner panel. Tighten the vapor canister
screws to 5 Nzm (45 in-lbs) torque.
(17) Right fender only: install the PDC, coolant re-
covery bottle and speed servo on the fender inner
panel.
(18) Right fender only: install the hood ajar switch,
if equipped. Tighten the screws to 2 Nzm (15 in-lbs)
torque.
(19) Right fender only: install the windshield
washer fluid reservoir on the inner panel.
(20) Right fender only: install the battery tray and
battery on the inner panel.
(21) Right fender only: if equipped, install the ra-
dio antenna. Tighten the nut/escutcheon to 4.5 Nzm
(40 in-lbs) torque. Tighten the power antenna bracket
screws to 2 Nzm (20 in-lbs) torque.
REAR WHEELHOUSE FLARES AND LINERSÐXJ
REMOVAL
(1) Remove the flare and liner lower screws (Fig.
53 and 54).
(2) Remove the nuts that attach the liner to the
wheelhouse.
(3) Remove the liner from the wheelhouse.
(4) Remove the push-nuts that attach the flare re-
tainers to the wheelhouse (Fig. 55).
(5) Remove the flare and retainers from the wheel-
house.
INSTALLATION
(1) Position the flare and retainers at the wheel-
house.
(2) Install the push-nuts to attach the flare retain-
ers to the wheelhouse.
(3) Position the liner in the wheelhouse.
Fig. 50 Fender Flare & Retainers
Fig. 51 Fender Liner and Retainers
Fig. 52 Front Lamp Wire Harness Connectors
JEXTERIOR COMPONENTSÐXJ 23 - 19