1995 JEEP YJ manual transmission

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

Throttle Valve and Downshift Plug
The throttle valve and downshift plug (Fig. 14) con-
trol throttle pressure to the primary regulator valve.
The downshift plug and throttle valve are operated
by the throttle valve cam and throttle cable in re-
sponse to engine throttle position. Throttle valve
pressure is also modulated by the cut-back valve in
second, third and fourth gear ranges.Cut-Back Valve
The cut-back valve (Fig. 15) helps prevent exces-
sive pump pressure buildup in second, third and
fourth gear. The valve is actuated by throttle pres-
sure and by line pressure from the second brake. The
valve also helps regulate line pressure by controlling
the amount of cut-back pressure to the throttle valve.
Fig. 12 Manual Valve
Fig. 13 Primary Regulator Valve
Fig. 14 Throttle Valve And Downshift Plug
Fig. 15 Cut-Back Valve
JAW-4 AUTOMATIC TRANSMISSION 21 - 171

When the transmission control module deactivates
the solenoid, line pressure at the top of the valve
moves the valve down closing the second brake accu-
mulator feed port. As the solenoid is activated and
the drain port opens, spring force moves the valve up
exposing the second brake feed port for the shift to
second gear.
2-3 Shift Valve
The 2-3 shift valve (Fig. 19) controls 2-3 upshifts
and downshifts. The valve is actuated by the No. 1
valve body solenoid and by line pressure from the
manual valve and primary regulator valve.When the TCM activates solenoid No. 1, line pres-
sure at the top of the 2-3 valve is released through
the solenoid drain port. Spring tension moves the
valve up to hold the valve in second gear position. As
the solenoid is deactivated, line pressure then moves
the valve down exposing the direct clutch feed port
for the shift to third gear.
3-4 Shift Valve
The 3-4 shift valve (Fig. 20) is operated by the No.
2 solenoid and by line pressure from the manual
valve, 2-3 valve and primary regulator valve.
Energizing the No. 2 solenoid causes line pressure
Fig. 19 2-3 Shift Valve
Fig. 20 3-4 Shift Valve
JAW-4 AUTOMATIC TRANSMISSION 21 - 173

at the top of the 3-4 valve to be released through the
solenoid valve drain port. Spring tension moves the
valve up exposing the overdrive clutch accumulator
feed port to apply the clutch.
De-energizing the solenoid causes the drain port to
close. Line pressure then moves the valve down ex-
posing the overdrive brake accumulator feed port for
the shift to fourth gear.
In the 1-2 or 3 gearshift lever positions, line pres-
sure from the 2-3 shift valve is applied to the lower
end of the 3-4 valve. This holds the valve upward,
closing off the overdrive brake feed port preventing a
shift into fourth gear.
Second Coast Modulator Valve
The second coast modulator valve (Fig. 21) momen-
tarily reduces line pressure from the 1-2 shift valve.
This cushions application of the second coast brake.
The valve is operative when the shift lever and man-
ual valve are in the 3 position.
Low Coast Modulator Valve
The low coast modulator valve (Fig. 22) momen-
tarily reduces line pressure from the 2-3 shift valve;
this action cushions application of the first/reverse
brake. The modulator valve operates when the shift
lever and manual valve are in the 1-2 position.
Accumulator Control Valve
The accumulator control valve (Fig. 23) cushions
clutch and brake application. This is achieved by re-
ducing back pressure to the accumulators when
throttle opening is small. The valve is operated by
line and throttle pressure.Accumulators
Four accumulators are used to cushion clutch and
brake application. The accumulators (Fig. 24), consist
of spring loaded pistons. The pistons dampen the ini-
tial surge of apply pressure to provide smooth en-
gagement during shifts.
Control pressure from the accumulator control
valve is continuously applied to the back pressure
side of the accumulator pistons. This pressure plus
spring tension holds the pistons down. As line pres-
sure from the shift valves enters the opposite end of
the piston bore, control pressure and spring tension
momentarily delay application of full line pressure to
Fig. 21 Second Coast Modulator Valve
Fig. 22 Low Coast Modulator Valve
Fig. 23 Accumulator Control Valve
21 - 174 AW-4 AUTOMATIC TRANSMISSIONJ

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

(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

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