1995 JEEP YJ service

ranges. Third gear ratio is 1:1. A separate planetary
gear set provides overdrive operation in fourth gear.
TRANSMISSION RANGES AND SHIFT LEVER
POSITIONS
The AW-4 transmission has six ranges and shift le-
ver positions. Park, Reverse and Neutral are conven-
tional and mechanically operated. The 1-2, 3 and D
ranges provide electronically controlled shifting.
The 1-2 position provides first and second gear
only. The 3 position provides first, second and third
gear.
The D range provides first through fourth gear.
Overdrive fourth gear range is available only when
the shift lever is in D position (Fig. 2).
TRANSMISSION IDENTIFICATION
The transmission I.D. plate is attached to the case
(Fig. 3). The plate contains the transmission serial
and model numbers. Refer to the information on this
plate when ordering service parts.
RECOMMENDED FLUID AND CAPACITY
Recommended and preferred fluid for the AW-4
transmission is Mopar Dexron IIE/Mercon.
Mopar Dexron II can be used but only in emer-
gency situations where Mercon fluid is not available.
Approximate refill capacity for the AW-4 is 8.0 li-
ters (16.9 pints or 8.45 quarts).
COMPONENTS AND OPERATION
ELECTRONIC CONTROLS
The AW-4 is electronically controlled in 1, 2, 3 and
D ranges. Controls consist of the transmission control
module (TCM), valve body solenoids and various sen-
sors. The sensors monitor vehicle speed, throttle
opening, shift lever position and brake pedal applica-
tion.
TRANSMISSION CONTROL MODULE (TCM)
The module determines shift and converter clutch
engagement timing based on signals from sensors.
The valve body solenoids are activated, or deacti-
vated accordingly.
The TCM has a self diagnostic program. Compo-
nent and circuitry malfunctions can be diagnosed
with the DRB scan tool. Once a malfunction is noted
and stored in control module memory, it is retained
even after the problem has been corrected. To cancel
a stored malfunction, disconnect and reconnect the
9Trans.9fuse in the module harness.
TRANSMISSION VALVE BODY SOLENOIDS
The solenoids are mounted on the valve body and
operated by the TCM. The solenoids control operation
of the converter clutch and shift valves in response to
input signals from the module.
SENSORS
Sensors include:
²throttle position sensor (TPS)
²transmission speed sensor
²vehicle speed sensor
²park/neutral position switch
²brake switch
The throttle position sensor is mounted on the
throttle body. It electronically determines throttle po-
sition and relays this information to the transmission
control module to determine shift points and con-
verter clutch engagement.
Fig. 2 AW-4 Shift Lever Positions And Transmission
Ranges
Fig. 3 Transmission Identification
21 - 166 AW-4 AUTOMATIC TRANSMISSIONJ

(2) Verify transmission throttle cable operation.
Repair or replace cable if necessary.
(3) Check engine throttle operation. Operate accel-
erator pedal and observe injector throttle plate move-
ment. Adjust linkage if throttle plate does not reach
wide open position.
(4) Check transmission fluid level when fluid is at
normal operating temperature. Start engine. Shift
transmission through all gear ranges then back to
Neutral. Correct level is to Full or Add mark on dip-
stick with engine at curb idle speed.
(5) Check and adjust park/neutral position switch
if necessary.
(6) Check throttle position sensor adjustment and
operation. Adjust the sensor if necessary.
MANUAL SHIFTING TEST
(1) This test determines if problem is related to
mechanical or electrical component.
(2) Stop engine and disconnect transmission con-
trol module or module fuse.
(3) Road test vehicle. Shift transmission into each
gear range. Transmission should operate as follows:
²lock in Park
²back up in Reverse
²not move in Neutral
²provide first gear only with shift lever in 1-2 posi-
tion
²operate in third gear only with shift lever in 3 po-
sition
²operate in overdrive fourth gear in D position
(4) If transmission operates as described, proceed
to next step. However, if forward gear ranges were
difficult to distinguish (all feel the same), or vehicle
would not back up, refer to diagnosis charts. Do not
perform stall or time lag tests.
CAUTION: Do not overspeed the engine during the
next test step. Ease off the throttle and allow the
vehicle to slow before downshifting.
(5) Continue road test. Manually downshift trans-
mission from D to 3, and from 3 to 1-2 position. Then
manually upshift transmission through forward
ranges again.
(6) If transmission operation is OK, perform stall,
time lag and pressure tests. If transmission shifting
problem is encountered, refer to diagnosis charts.
(7) If a problem still exists, continue testing with
DRB scan tool.
HYDRAULIC PRESSURE TEST
PRESSURE TEST PROCEDURE
(1) Connect pressure test gauge to test port on pas-
senger side of transmission. Use Adapter 7554 to con-
nect gauge. Be sure test gauge has minimum
capacity of 300 psi (2100 kPa).(2) Be sure transmission fluid is at normal operat-
ing temperature.
(3) Apply parking brakes and block wheels.
WARNING: DO NOT ALLOW ANYONE TO STAND
AT THE FRONT OR REAR OF THE VEHICLE WHILE
PERFORMING THE FOLLOWING STEPS IN THE
PRESSURE TEST.
(4) Check and adjust engine curb idle speed.
(5) Apply (and hold) service brakes.
(6) Shift transmission into D range and note line
pressure with engine at curb idle speed. Pressure
should be 61-to-70 psi (421-to-481 kPa).
(7) Press accelerator pedal to wide open throttle
position and note line pressure. Pressure should be
173-to-209 psi (1196-to-1442 kPa).
CAUTION: Do not hold wide open throttle for more
than 3-4 seconds at a time.
(8) Shift transmission into Reverse and note line
pressure with engine at curb idle speed. Pressure
should be 75-to-90 psi (519-to-618 kPa).
(9) Press accelerator to wide open throttle position
and note line pressure in Reverse. Pressure should
be 213-to-263 psi (1471-to-1814 kPa).
CAUTION: Do not hold wide open throttle for more
than 4 seconds.
(10) If line pressure is not within specifications,
adjust transmission throttle cable and repeat pres-
sure test.
Fig. 27 Pressure Test Gauge Connection
JAW-4 TRANSMISSION DIAGNOSIS 21 - 177

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

SERVICE DIAGNOSIS
21 - 180 AW-4 TRANSMISSION DIAGNOSISJ

SERVICE DIAGNOSIS
JAW-4 TRANSMISSION DIAGNOSIS 21 - 181

AW-4 IN-VEHICLE SERVICE
INDEX
page page
Accumulator Pistons and Springs............. 189
Adapter Housing Seal Replacement........... 191
Checking Fluid Level and Condition........... 182
Manual Valve Shaft Seal Replacement......... 187
Park Interlock Cable Adjustment............. 195
Park Rod and Pawl Service................. 190
Park/Neutral Position Switch................ 183
Refilling After Overhaul or Fluid/Filter Change . . . 182
Second Coast Brake Servo................. 190
Shift Cable Adjustment.................... 195
Speed Sensor........................... 192Speed Sensor RotorÐSpeedometer Drive Gear . . 193
Throttle Position Sensor (TPS) Service........ 193
Transmission Control Module (TCM) Service.... 183
Transmission Cooler Line Fittings............ 197
Transmission Cooler Service................ 196
Transmission Throttle Cable Adjustment........ 194
Transmission Throttle Cable Replacement...... 193
Transmission Valve Body Installation.......... 187
Transmission Valve Body Removal........... 186
Transmission Valve Body Solenoids........... 184
CHECKING FLUID LEVEL AND CONDITION
Recommended fluid for AW-4 transmissions is Mo-
par Dexron IIE/Mercon.
Mopar Dexron II can also be used but only when
Mercon fluid is not available.
CHECKING FLUID LEVEL
(1) Be sure transmission fluid is at normal operat-
ing temperature. Normal operating temperature is
reached after approximately 15 miles (25 km) of op-
eration.
(2) Position vehicle on level surface. This is impor-
tant for an accurate fluid level check.
(3) Shift transmission through all gear ranges and
back to Park.
(4) Apply parking brakes.
(5) Verify that transmission is in Park.
(6) Wipe off dipstick handle to prevent dirt from
entering fill tube. Then remove dipstick and check
fluid level and condition.
(7) Correct fluid level isto FULL mark on dip-
stick when fluid is at normal operating temper-
ature(Fig. 1).
(8) If fluid level is low, top off level with Mopar
Dexron IIE/Mercon. Mopar Dexron II can be used but
only if Mercon is not available.Do not overfill
transmission. Add only enough fluid to bring
level to Full mark.
(9) If too much fluid was added, excess amount can
be removed with suction gun and appropriate diame-
ter plastic tubing. Tubing only has to be long enough
to extend into oil pan.
CHECKING FLUID CONDITION
Inspect the appearance of the fluid during the fluid
level check. Fluid color should range from dark red to
pink and be free of foreign material, or particles. If
the fluid is dark brown or black in color and smells
burnt, the fluid has been overheated and must be
changed.Transmission operation should also be checked if
the fluid is severely discolored and contains quanti-
ties of foreign material, metal particles, or clutch disc
friction material.
A small quantity of friction material or metal
particles in the oil pan is normal. The particles
are usually generated during the break-in pe-
riod and indicate normal seating of the various
transmission components.
REFILLING AFTER OVERHAUL OR FLUID/FILTER
CHANGE
The best way to refill the transmission after a fluid
change or overhaul is as follows:
(1) If transmission has been overhauled, install
transmission in vehicle.
(2) Remove dipstick and insert clean funnel in
transmission fill tube.
(3) Add following initial quantity of Mopar Dexron
IIE/Mercon to transmission:
(a) If fluid/filter change was performed, add4
pints (2 quarts)of fluid to transmission.
(b) If transmission was completely overhauled
and torque converter was replaced or drained, add
10 pints (5 quarts)of fluid to transmission.
(c) Remove funnel and install dipstick.
(4) Operate vehicle until fluid reaches normal op-
erating temperature.
(5) Apply parking brakes.
Fig. 1 Transmission Fluid Level
21 - 182 AW-4 IN-VEHICLE SERVICEJ

(6) Let engine run at normal curb idle speed, apply
service brakes. Then shift transmission through all
gear ranges and back to PARK (leave engine run-
ning).
(7) Remove dipstick and check fluid level. Add only
enough fluid to bring level to Full mark on dipstick.
Do not overfill.If too much fluid is added, excess
amount can be removed with suction gun and
plastic tubing. Tubing only has to be long
enough to extend into oil pan.
(8) When fluid level is correct, shut engine off, re-
lease park brake, remove funnel, and reseat dipstick
in fill tube.
TRANSMISSION CONTROL MODULE (TCM)
SERVICE
Use the DRB scan tool to diagnose transmission
control module function whenever a fault is sus-
pected. Replace the module only when the scan tool
indicates the module is actually faulty.
TRANSMISSION CONTROL MODULE
REPLACEMENT
The transmission control module is mounted under
the instrument panel. On left hand drive models, it is
at the driver side of the lower finish panel (Fig. 2).
On right hand drive models, it is at the passenger
side of the lower finish panel (Fig. 3).
To remove the module, disconnect the wire harness,
remove the mounting screws and remove the module
from the finish panel. Tighten the module mounting
screws securely after installation. Also be sure the
wire harness is not twisted, kinked or touching any
body panels.
PARK/NEUTRAL POSITION SWITCH
SWITCH TESTING
Test switch continuity with an ohmmeter. Discon-
nect the switch and check continuity at the connector
terminal positions and in the gear ranges indicated
in Figure 3. Switch continuity should be as follows:
²Continuity should exist between terminals B and
C with the transmission in Park and Neutral only
(Fig. 4).²Continuity should exist between terminals A and E
with the transmission in Reverse (Fig. 4).
²Continuity should exist between terminals A and
G with the transmission in third gear (Fig. 4).
²Continuity should exist between terminals A and
H with the transmission in first and/or second gear
(Fig. 4).
²Continuity should not exist in D position.
PARK/NEUTRAL POSITION SWITCH REMOVAL
(1) Raise vehicle.
(2) Disconnect switch wire harness connector.
(3) Pry washer lock tabs upward and remove
switch attaching nut and tabbed washer (Fig. 5).
(4) Remove switch adjusting bolt (Fig. 5).
(5) Slide switch off manual valve shaft.
PARK/NEUTRAL POSITION SWITCH
INSTALLATION AND ADJUSTMENT
(1) Disconnect shift linkage rod from shift lever on
left side of transmission.
Fig. 2 TCM Location (Left Hand Drive)
Fig. 3 TCM Location (Right Hand Drive)
Fig. 4 Park/Neutral Position Switch Terminals And
Testing
JAW-4 IN-VEHICLE SERVICE 21 - 183

(2) Rotate manual shift lever all the way rearward.
Then rotate lever forward two detent positions to
Neutral.
(3) Install switch on manual valve shaft and in-
stall switch adjusting bolt finger tight. Do not tighten
bolt at this time.
(4) Install tabbed washer on manual valve shaft
and install switch attaching nut. Tighten nut to 6.9
Nzm (61 in. lbs.) torque but do not bend washer lock
tabs over nut at this time.
(5) Verify that transmission is in Neutral.
(6) Rotate switch to align neutral standard line
with vertical groove on manual valve shaft (Fig. 6).
(7) Align switch standard line with groove or flat
on manual valve shaft.
(8) Tighten switch adjusting bolt to 13 Nzm(9ft.
lbs.) torque.
(9) Bend at least two washer lock tabs over switch
attaching nut to secure it.
(10) Connect shift linkage rod to shift lever on left
side of case.
(11) Connect switch wires to harness and lower ve-
hicle.
(12) Check switch operation. Engine should start
in Park and Neutral only.
TRANSMISSION VALVE BODY SOLENOIDS
SOLENOID REMOVAL
(1) Remove transmission oil pan drain plug and
drain fluid.
(2) Remove pan bolts and remove oil pan.(3) Remove oil screen bolts and remove screen (Fig.
7) and gasket. Discard the gasket.
(4) Disconnect solenoid wire connector (Fig. 8).
(5) If all solenoids are being removed, mark or tag
wires for assembly reference before disconnecting
them.
(6) Remove bolt attaching solenoids to valve body
and remove solenoids (Fig. 9). Do not allow any valve
body components to fall out when solenoids are re-
moved.
(7) Clean oil filter and pan with solvent and dry
with compressed air.
(8) Remove old sealer material from oil pan and
transmission case.
Fig. 5 Park/Neutral Position Switch Removal/
Installation
Fig. 6 Park/Neutral Position Switch Adjustment
Fig. 7 Oil Screen Removal/Installation
21 - 184 AW-4 IN-VEHICLE SERVICEJ