1995 JEEP YJ brakes

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

The manual valve, 1-2 shift valve, primary regula-
tor valve, accumulator control valve, check balls, so-
lenoids and oil strainers are located in the lower
body section (Fig. 10). The remaining control and
shift valves plus check balls and one additional oil
strainer are located in the upper body section (Fig.
11).
Manual Valve
The manual valve is operated by the gearshift link-
age. The valve diverts fluid to the apply circuits ac-
cording to shift lever position.Primary Regulator Valve
The primary regulator valve (Fig. 13) modulates
line pressure to the clutches and brakes according to
engine load. The valve is actuated by throttle valve
pressure.
During high load operation, the valve increases line
pressure to maintain positive clutch and brake en-
gagement. At light load, the valve decreases line
pressure just enough to maintain smooth engage-
ment.
Fig. 10 Upper Body Components
Fig. 11 Lower Body Components
21 - 170 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

(3) Apply parking brakes and turn off air condi-
tioning unit.
(4) Shift transfer case into 2H 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.
(8) Shift transmission into D range and record
time it takes for engagement. Repeat test two more
times.
(9) Reset stop watch and shift transmission back to
Neutral.
(10) Shift transmission into Reverse and record
time it takes for engagement. Repeat test two more
times.(11) Engagement time in D range should be a max-
imum of 1.2 seconds. Engagement time for Reverse
should be a maximum of 1.5 seconds.
TIME LAG TEST ANALYSIS
If engagement time is longer than specified for D
range, check for the following:
²shift cable misadjusted
²line pressure low
²forward clutch worn
²overdrive clutch worn or damaged
If engagement time is longer than specified for Re-
verse, check for the following:
²shift cable misadjusted
²line pressure low
²direct clutch worn
²first/reverse brake worn
²overdrive clutch worn or damaged
JAW-4 TRANSMISSION DIAGNOSIS 21 - 179

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