1995 JEEP YJ torque

AW-4 AUTOMATIC TRANSMISSION
CONTENTS
page page
AW-4 AUTOMATIC TRANSMISSION........ 165
AW-4 IN-VEHICLE SERVICE.............. 182
AW-4 TRANSMISSION DIAGNOSIS......... 176
AW-4 TRANSMISSION OVERHAUL......... 201AW-4 TRANSMISSION REMOVAL AND
INSTALLATION....................... 198
GENERAL INFORMATION................ 165
GENERAL INFORMATION
INDEX
page page
Components and Operation................. 166
Description............................. 165
First/Second/Third/Reverse Components....... 168
Fourth Gear Overdrive Components.......... 167
Geartrain Operation and Application Charts..... 169Hydraulic System........................ 169
Recommended Fluid and Capacity........... 166
Torque Converter........................ 167
Transmission Identification.................. 166
Transmission Ranges and Shift Lever Positions . . 166
DESCRIPTION
AW-4 Transmission Overhaul
The AW-4 is a 4-speed, electronically controlled au-
tomatic transmission (Fig. 1). The AW-4 is used in XJ
models with a 4.0L engine.
Running gear consists of an oil pump, planetary
gear sets, clutch and brake units, hydraulic accumu-
lators, a valve body with electrical solenoids and a
transmission control module (TCM). Cables are usedfor shift and throttle pressure control. A park/neutral
position switch permits engine starting in Park and
Neutral range only.
The valve body solenoids are controlled by signals
from the transmission control module (TCM). Signal
sequence is determined by vehicle speed and throttle
position.
Fourth gear is an 0.75:1 ratio overdrive range.
First, second, third and reverse gear are conventional
Fig. 1 AW-4 Automatic Transmission
JAW-4 AUTOMATIC TRANSMISSION 21 - 165

The transmission speed sensor consists of a rotor
and magnet on the transmission output shaft and a
switch in the extension housing or adapter. The sen-
sor switch is activated each time the rotor and mag-
net complete one revolution. Sensor signals are sent
to the transmission control module.
The park/neutral position switch is mounted on the
valve body manual shaft. The switch signals shift
linkage and manual valve position to the transmis-
sion control module through an interconnecting har-
ness. The switch prevents engine starting in all gears
other than Park or Neutral.
The brake switch is in circuit with the torque con-
verter clutch solenoid. The switch disengages the
converter clutch whenever the brakes are applied.
The switch is mounted on the brake pedal bracket
and signals the transmission control module when
the pedal is pressed or released.
TORQUE CONVERTER
A three element torque converter is used for all ap-
plications. The converter contains an impeller, stator,
and turbine.
The AW-4 converters are all equipped with a con-
verter clutch mechanism. The clutch consists of a
sliding clutch piston, clutch springs and the clutch
disc material (Fig. 4). The clutch provides optimum
torque transfer and economy when engaged.
The clutch disc is attached to the converter front
cover. The clutch piston and clutch springs are at-
tached to the turbine hub. The springs dampen en-
gine firing impulses and loads during the initial
phase of converter clutch engagement.
Clutch engagement is controlled by transmission
valve body solenoid number three and by the con-
verter clutch relay valve. The solenoid channels line
pressure to the clutch through the relay valve at
clutch engagement speeds.Torque converter clutch engagement occurs in sec-
ond gear in 1-2 position; third gear in 3 position and
third and fourth gear in D position.
FOURTH GEAR OVERDRIVE COMPONENTS
The overdrive system consists of the input shaft,
one-way clutch, planetary sun gear, ring gear, plane-
tary carrier, clutch and overdrive brake (Fig. 5). The
overdrive elements are controlled and applied
through transmission valve body solenoid number
two.
In overdrive fourth gear, the brake prevents the
overdrive sun gear from turning. During operation,
the overdrive elements operate as follows:
Fig. 4 Torque Converter (With Clutch)
Fig. 5 Fourth Gear Overdrive Components
JAW-4 AUTOMATIC TRANSMISSION 21 - 167

The rear planetary ring gear is splined to the out-
put shaft. The front planetary carrier and rear car-
rier ring gear are meshed and rotate as a unit with
the output shaft.
GEARTRAIN OPERATION AND APPLICATION
CHARTS
Operation and application of the first through
fourth and reverse gear elements are outlined in the
function and application charts.
The Component Function Chart (Fig. 7) describes
basic function of various geartrain elements. The
Component Application Chart (Fig. 8) indicates
which elements (including valve body solenoids), are
applied in the various gear ranges.
HYDRAULIC SYSTEM
The hydraulic system consists of the pump, valve
body and solenoids, and four hydraulic accumulators.
The oil pump provides lubrication and operating
pressure.
The valve body controls application of the clutches,
brakes, second coast band, and the converter clutch.
The valve body solenoids control sequencing of the
1-2, 2-3 and 3-4 shift valves. The solenoids are acti-
vated by signals from the transmission control mod-
ule.
The accumulators are used in the clutch and brake
feed circuits to control initial apply pressure. Spring
loaded accumulator pistons modulate the initial
surge of apply pressure for smooth engagement.
OIL PUMP
A gear-type oil pump is used. The pump gears are
mounted in the pump body. The pump drive gear isoperated by the torque converter hub. Drive tangs on
the hub engage in drive slots in the drive gear.
TRANSMISSION VALVE BODY COMPONENTS
Transmission operating pressure is supplied to the
clutch and brake apply circuits through the transmis-
sion valve body. The valve body consists of an upper
body, lower body, separator plate and upper and
lower gaskets (Fig. 9). The various spool valves,
sleeves, plugs and springs are located within the two
body sections.
Fig. 8 Component Application Chart
Fig. 9 Two-Section Transmission Valve Body
JAW-4 AUTOMATIC TRANSMISSION 21 - 169

cushion engagement. The accumulators are all lo-
cated in the transmission case (Fig. 24).
Transmission Valve Body Solenoids
Three solenoids are used (Fig. 25). The No. 1 and 2
solenoids control shift valve operation by applying orreleasing line pressure. The signal to apply or release
pressure is provided by the transmission control
module.
The No. 3 solenoid controls operation of the torque
converter clutch. The solenoid operates in response to
signals from the transmission control module.
When the No. 1 and 2 solenoids are activated, the
solenoid plunger is moved off its seat opening the
drain port to release line pressure. When either sole-
noid is deactivated, the plunger closes the drain port.
The No. 3 solenoid operates in reverse. When the
solenoid is deactivated, the solenoid plunger is moved
off its seat opening the drain port to release line
pressure. When the solenoid is activated, the plunger
closes the drain port.
Fig. 24 Accumulators
Fig. 25 Transmission Valve Body Solenoids
JAW-4 AUTOMATIC TRANSMISSION 21 - 175

AW-4 TRANSMISSION DIAGNOSIS
INDEX
page page
General Diagnosis Information............... 176
Hydraulic Pressure Test.................... 177
Manual Shifting Test...................... 177Preliminary Inspection and Adjustment......... 176
TimeLagTest ........................... 178
Torque Converter Stall Test................. 178
GENERAL DIAGNOSIS INFORMATION
Shift points are controlled by the transmission con-
trol module (TCM). Before attempting repair, deter-
mine if a malfunction is electrical or mechanical.
The TCM used with the AW-4 transmission has a
self-diagnostic program compatible with the DRB
scan tool. The tester will identify faults in the elec-
trical control system.
Diagnosis should begin with the Preliminary Inspec-
tion And Adjustment procedure. It is will help deter-
mine if a problem is mechanical or electrical. The first
procedure step is Initial Inspection and Adjustment.
PRELIMINARY INSPECTION AND ADJUSTMENT
(1) Check and adjust transmission shift cable if
necessary.
Fig. 26 Preliminary Diagnosis Check Procedure
21 - 176 AW-4 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

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

(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