four wheel drive DODGE RAM 1500 1998 2.G Owner's Manual

INSTALLATION
NOTE: If a new transmission is being installed, use all
components supplied with the new transmission. For
example, if a new shift tower is supplied with the new
transmission, do not re-use the original shift tower.
(1) Apply light coat of Mopar high temperature
bearing grease or equivalent to contact surfaces of
the following components:
²input shaft splines.
²release bearing slide surface of front retainer.
²release bearing bore.
²release fork.
²release fork ball stud.
²propeller shaft slip yoke.
(2) Apply sealer to threads of bottom PTO cover
bolt and install bolt in case.
(3) Mount transmission on jack and position trans-
mission under vehicle.
(4) Raise transmission until input shaft is centered
in release bearing and clutch disc hub.
(5)
Move transmission forward and start input shaft
in release bearing, clutch disc and pilot bushing.
(6)Work transmission forward until seated against
clutch housing. Do not allow transmission to remain
unsupported after input shaft has entered clutch disc.
(7) Install transmission bolts and tighten to 108
N´m (80 ft. lbs.).
(8) Install transmission mount on transmission or
rear crossmember.
(9) Install rear crossmember.
(10) Remove transmission jack and engine support
fixture.
(11) Position transmission harness wires in clips
on shift cover.
(12) Install clutch slave cylinder and install slave
cylinder shield, if equipped.
(13) Connect speed sensor and backup light switch
wires.
TWO WHEEL DRIVE
(1) Fill transmission with recommended lubricant.
Correct fill level is bottom edge of fill plug hole.
(2) Align and install propeller shaft.
(3) Lower vehicle.
(4) Clean the mating surfaces of shift tower, isola-
tor plate and shift cover with suitable wax and
grease remover.
(5) Apply Mopar Gasket Maker or equivalent to
the sealing surface of the shift cover. Do not over
apply sealant.
(6) Install the isolator plate onto the shift cover,
metal side down.
(7) Install the shift tower onto the isolator plate.
No sealant is necessary between the shift tower and
the isolator plate.(8) Verify that the shift tower, isolator plate and
the shift tower bushings are properly aligned.
(9) Install the bolts to hold the shift tower to the
isolator plate and the shift cover. Tighten the shift
tower bolts to 10.2-11.25 N´m (7.5-8.3 ft. lbs.).
(10) Install the shift lever extension onto the shift
tower and lever assembly.
(11) Install shift boot and bezel.
(12) Connect battery negative cable.
FOUR WHEEL DRIVE
(1) Install transfer case shift mechanism on trans-
mission.
(2) Install transfer case on transmission jack.
Secure transfer case to jack with safety chains.
(3) Raise jack and align transfer case input gear
with transmission mainshaft.
(4) Move transfer case forward and seat it on
adapter.
(5) Install transfer case nuts and tighten to:
²If 3/8 studs 41-47 N´m (30-35 ft. lbs.).
²If 5/16 studs 30-41 N´m (22-30 ft. lbs.).
(6) Install transfer case shift mechanism to side of
transfer case.
(7) Connect transfer case shift lever to range lever
on transfer case.
(8) Align and connect propeller shafts.
(9) Fill transmission with required lubricant.
Check lubricant level in transfer case and add lubri-
cant if necessary.
(10) Install transfer case skid plate, if equipped
and crossmember. Tighten attaching bolts/nuts to 41
N´m (30 ft. lbs.).
(11) Install exhaust system components.
(12) Lower vehicle.
(13) Clean the mating surfaces of shift tower, iso-
lator plate and shift cover with suitable wax and
grease remover.
(14) Apply Mopar Gasket Maker or equivalent to
the sealing surface of the shift cover. Do not over
apply sealant.
(15) Install the isolator plate onto the shift cover,
metal side down.
(16) Install the shift tower onto the isolator plate.
No sealant is necessary between the shift tower and
the isolator plate.
(17) Verify that the shift tower, isolator plate and
the shift tower bushings are properly aligned.
(18) Install the bolts to hold the shift tower to the
isolator plate and the shift cover. Tighten the shift
tower bolts to 10.2-11.25 N´m (7.5-8.3 ft. lbs.).
(19) Install the shift lever extension onto the shift
tower and lever assembly.
(20) Install shift lever boot and bezel.
(21) Connect battery negative cable.
21 - 80 MANUAL TRANSMISSION - NV4500DR
MANUAL TRANSMISSION - NV4500 (Continued)

(2) Remove screws attaching shift boot to floorpan.
Then slide boot upward on the shift lever.
(3) Remove the bolts holding the shift tower to the
isolator plate and transmission gear case.
(4) Remove the shift tower and isolator plate from
the transmission gear case.
(5) Raise and support vehicle.
(6) Remove skid plate, if equipped.
(7) Mark propeller shaft/shafts and axle yokes for
installation reference.
(8) Remove propeller shaft.
(9) Disconnect and remove exhaust system as nec-
essary.
(10) Disconnect wires at backup light switch.
(11) Support engine with adjustable safety stand
and wood block.
(12) If transmission is to be disassembled for
repair, remove drain bolt at bottom of PTO cover and
drain lubricant from transmission (Fig. 3).
(13) Remove clutch slave cylinder splash shield, if
equipped.
(14) Remove clutch slave cylinder bolts and move
cylinder aside for clearance.
(15)
Remove wire harness from clips on transmission.
TWO WHEEL DRIVE
(1) Remove bolts/nuts mounting transmission to
the rear mount.
(2) Support and secure transmission with safety
chains to a transmission jack.
(3) Remove rear crossmember bolts and pry out
crossmember.
(4) Remove transmission clutch housing bolts at
the engine block.
(5) Slide transmission and jack rearward until
input shaft clears clutch disc and pressure plate.
(6) Lower transmission jack and remove transmis-
sion from under vehicle.
FOUR WHEEL DRIVE
(1) Disconnect transfer case shift linkage at trans-
fer case range lever.
(2) Support and secure transfer case with safety
chains to a transmission jack.
(3) Remove transfer case mounting nuts.
(4) Move transfer case rearward until input gear
clears transmission mainshaft.
(5) Lower transfer case assembly and move it from
under vehicle.
(6) Support and secure transmission with safety
chains to a transmission jack.
(7) Remove bolts/nuts attaching transmission
mount to rear crossmember.
(8) Remove rear crossmember bolts and pry out
crossmember.
(9) Remove transmission clutch housing bolts at
the engine block.
(10) Move transmission rearward until input shaft
clears clutch disc.
(11) Lower transmission and remove it from under
vehicle.
DISASSEMBLY
NOTE: Use Fixture 8241 for moving and handling
the transmission. The fixture supports the transmis-
sion at the center of gravity in order to ease mount-
ing the transmission into the build fixture.
(1)
Mount the transmission into Fixture 8230 (Fig. 4).
Fig. 3 NV5600 DRAIN BOLT
1 - PTO COVER
2 - DRAIN BOLT
Fig. 4 TRANSMISSION FIXTURE
1 - FIXTURE
2 - TRANSMISSION
DRMANUAL TRANSMISSION - NV5600 21 - 91
MANUAL TRANSMISSION - NV5600 (Continued)

(1) Apply a light coat of Mopar high temperature
bearing grease or equivalent to contact surfaces of
following components:
²input shaft splines.
²release bearing slide surface of front retainer.
²release bearing bore.
²release fork.
²release fork ball stud.
²propeller shaft slip yoke.
(2) Apply sealer to threads of bottom PTO cover
bolt and install bolt in case.
(3) Mount transmission on jack and position trans-
mission under vehicle.
(4) Raise transmission until input shaft is centered
in clutch disc hub.
(5) Move transmission forward and start input
shaft in clutch disc and pilot bushing/bearing.
(6)
Work transmission forward until seated against
engine block. Do not allow transmission to remain
unsupported after input shaft has entered clutch disc.
(7) Install and tighten transmission-to-engine
block bolts.
(8) Install clutch slave cylinder.
(9) Connect backup light switch wires.
(10) Position transmission harness wires in clips
on transmission.
(11) Install transmission mount on transmission or
rear crossmember.
(12) Install rear crossmember.
(13) Remove transmission jack and engine support
fixture.
(14)
Fill transmission with required lubricant (Fig.
96). Check lubricant level in transfer case if equipped.
TWO WHEEL DRIVE
(1) Install propeller shaft with referece marks
aligned.
(2) Install exhaust system components.(3) Remove support and lower vehicle.
(4) Shift transmission into third gear.
(5) Clean the mating surfaces of shift tower and
isolator plate with suitable wax and grease remover.
(6) Apply Mopar Gasket Maker or equivalent to
sealing surface of the transmission case. Do not over
apply sealant.
(7) Install isolator plate onto the transmission case
metal side down.
(8) Install shift tower onto the isolator plate. No
sealant is necessary between the shift tower and top
of isolator plate.
(9) Verify shift tower, isolator plate and the shift
socket are properly aligned.
(10) Install bolts to hold the shift tower to the iso-
lator plate and the transmission case. Tighten bolts
to 10.2±11.25 N´m (7.5±8.3 ft. lbs.).
(11) Install shift boot and bezel.
FOUR WHEEL DRIVE
(1) Install and secure transfer case on the trans-
mission jack.
(2) Raise and align transfer case input gear with
transmission mainshaft.
(3) Move transfer case forward and seat it on
adapter.
(4)
Install and tighten transfer case mounting nuts to
41-47 N´m (30-35 ft. lbs.) if case has 3/8 studs. If case
has 5/16 studs tighten to 30-41 N´m (22-30 ft. lbs.).
(5) Connect transfer case shift lever to range lever
on transfer case.
(6) Install propeller shafts with reference marks
aligned.
(7) Install transfer case skid plate, if equipped,
and crossmember. Tighten attaching bolts/nuts to 41
N´m (30 ft. lbs.).
(8) Install exhaust system components.
(9) Remove support and lower vehicle.
(10) Shift transmission into third gear.
(11) Clean the mating surfaces of shift tower, iso-
lator plate and transmission case with suitable wax
and grease remover.
(12) Apply Mopar Gasket Maker or equivalent to
the sealing surface of the transmission case. Do not
over apply sealant.
(13) Install isolator plate onto the transmission
case, metal side down.
(14) Install shift tower onto the isolator plate. No
sealant is necessary between the shift tower and top
of isolator plate.
(15) Verify that the shift tower, isolator plate and
the shift tower bushings are properly aligned.
(16) Install the bolts to hold the shift tower to the
isolator plate and the transmission case. Tighten the
shift tower bolts to 10.2-11.25 N´m (7.5-8.3 ft. lbs.).
(17) Install shift lever boot and bezel.
Fig. 96 FILL PLUG
1 - FILL PLUG
21 - 122 MANUAL TRANSMISSION - NV5600DR
MANUAL TRANSMISSION - NV5600 (Continued)

DIRECT DRIVE POWERFLOW
The vehicle has accelerated and reached the shift
point for the 2-3 upshift into direct drive (Fig. 8).
When the shift takes place, the front band is
released, and the front clutch is applied. The rear
clutch stays applied as it has been in all the forward
gears. With the front clutch now applied, engine
torque is now on the front clutch retainer, which is
locked to the sun gear driving shell. This means that
the sun gear is now turning in engine rotation (clock-
wise) and at engine speed. The rear clutch is still
applied so engine torque is also still on the front
annulus gear. If two members of the same planetary
set are driven, direct drive results. Therefore, when
two members are rotating at the same speed and in
the same direction, it is the same as being locked up.
The rear planetary set is also locked up, given the
sun gear is still the input, and the rear annulus gear
must turn with the output shaft. Both gears are
turning in the same direction and at the same speed.
The front and rear planet pinions do not turn at all
in direct drive. The only rotation is the input from
the engine to the connected parts, which are acting
as one common unit, to the output shaft.
FOURTH GEAR POWERFLOW
Fourth gear overdrive range is electronically con-
trolled and hydraulically activated. Various sensor
inputs are supplied to the powertrain control module
to operate the overdrive solenoid on the valve body.
The solenoid contains a check ball that opens and
closes a vent port in the 3-4 shift valve feed passage.
The overdrive solenoid (and check ball) are not ener-
gized in first, second, third, or reverse gear. The vent
port remains open, diverting line pressure from the
2-3 shift valve away from the 3-4 shift valve. The
Tow/Haul control switch must be in the ON position
to transmit overdrive status to the PCM. A 3-4
upshift occurs only when the overdrive solenoid is
energized by the PCM. The PCM energizes the over-
drive solenoid during the 3-4 upshift. This causes the
solenoid check ball to close the vent port allowing
line pressure from the 2-3 shift valve to act directly
on the 3-4 upshift valve. Line pressure on the 3-4
shift valve overcomes valve spring pressure moving
the valve to the upshift position. This action exposes
the feed passages to the 3-4 timing valve, 3-4 quick
fill valve, 3-4 accumulator, and ultimately to the
overdrive piston. Line pressure through the timing
Fig. 8 Direct Drive Powerflow
1 - FRONT CLUTCH APPLIED 6 - INPUT SHAFT
2 - OVER-RUNNING CLUTCH FREE-WHEELING 7 - OVER-RUNNING CLUTCH FREE-WHEELING
3 - OUTPUT SHAFT 8 - REAR CLUTCH APPLIED
4 - REAR CLUTCH APPLIED 9 - FRONT CLUTCH APPLIED
5 - OUTPUT SHAFT 10 - INPUT SHAFT
DRAUTOMATIC TRANSMISSION - 48RE 21 - 139
AUTOMATIC TRANSMISSION - 48RE (Continued)

valve moves the overdrive piston into contact with
the overdrive clutch. The direct clutch is disengaged
before the overdrive clutch is engaged. The boost
valve provides increased fluid apply pressure to the
overdrive clutch during 3-4 upshifts, and when accel-
erating in fourth gear. The 3-4 accumulator cushions
overdrive clutch engagement to smooth 3-4 upshifts.
The accumulator is charged at the same time as
apply pressure acts against the overdrive piston.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - AUTOMATIC
TRANSMISSION
Automatic transmission problems can be a result of
poor engine performance, incorrect fluid level, incor-
rect linkage or cable adjustment, band or hydraulic
control pressure adjustments, hydraulic system mal-
functions or electrical/mechanical component mal-
functions. Begin diagnosis by checking the easily
accessible items such as: fluid level and condition,
linkage adjustments and electrical connections. A
road test will determine if further diagnosis is neces-
sary.
DIAGNOSIS AND TESTING - PRELIMINARY
Two basic procedures are required. One procedure
for vehicles that are drivable and an alternate proce-
dure for disabled vehicles (will not back up or move
forward).
VEHICLE IS DRIVEABLE
(1) Check for transmission fault codes using DRBt
scan tool.
(2) Check fluid level and condition.
(3) Adjust throttle and gearshift linkage if com-
plaint was based on delayed, erratic, or harsh shifts.
(4) Road test and note how transmission upshifts,
downshifts, and engages.
(5) Perform hydraulic pressure test if shift prob-
lems were noted during road test.
(6) Perform air-pressure test to check clutch-band
operation.
VEHICLE IS DISABLED
(1) Check fluid level and condition.
(2) Check for broken or disconnected gearshift or
throttle linkage.
(3) Check for cracked, leaking cooler lines, or loose
or missing pressure-port plugs.
(4) Raise and support vehicle on safety stands,
start engine, shift transmission into gear, and note
following:
(a) If propeller shaft turns but wheels do not,
problem is with differential or axle shafts.
(b) If propeller shaft does not turn and transmis-
sion is noisy, stop engine. Remove oil pan, and
check for debris. If pan is clear, remove transmis-
sion and check for damaged drive plate, converter,
oil pump, or input shaft.
(c) If propeller shaft does not turn and transmis-
sion is not noisy, perform hydraulic-pressure test to
determine if problem is hydraulic or mechanical.
DIAGNOSIS AND TESTING - ROAD TESTING
Before road testing, be sure the fluid level and con-
trol cable adjustments have been checked and
adjusted if necessary. Verify that diagnostic trouble
codes have been resolved.
Observe engine performance during the road test.
A poorly tuned engine will not allow accurate analy-
sis of transmission operation.
Operate the transmission in all gear ranges. Check
for shift variations and engine flare which indicates
slippage. Note if shifts are harsh, spongy, delayed,
early, or if part throttle downshifts are sensitive.
Slippage indicated by engine flare, usually means
clutch, band or overrunning clutch problems. If the
condition is advanced, an overhaul will be necessary
to restore normal operation.
A slipping clutch or band can often be determined
by comparing which internal units are applied in the
various gear ranges. The Clutch and Band Applica-
tion chart provides a basis for analyzing road test
results.
21 - 140 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)

The rear servo and governor pressure ports are at
the right rear of the transmission case. The overdrive
clutch pressure port is at the left rear of the case.
Test One - Transmission In Manual Low
This test checks pump output, pressure regulation,
and condition of the rear clutch and servo circuit.
Both test gauges are required for this test.
(1) Connect tachometer to engine. Position tachom-
eter so it can be observed from driver seat if helper
will be operating engine. Raise vehicle on hoist that
will allow rear wheels to rotate freely.
(2) Connect 100 psi Gauge C-3292 to accumulator
port. Then connect 300 psi Gauge C-3293-SP to rear
servo port.
(3) Disconnect throttle and gearshift cables from
levers on transmission valve body manual shaft.
(4) Have helper start and run engine at 1000 rpm.
(5) Move transmission shift lever fully forward
into 1 range.
(6) Gradually move transmission throttle lever
from full forward to full rearward position and note
pressures on both gauges:²Line pressure at accumulator port should be
54-60 psi (372-414 kPa) with throttle lever forward
and gradually increase to 90-96 psi (621-662 kPa) as
throttle lever is moved rearward.
²Rear servo pressure should be same as line pres-
sure within 3 psi (20.68 kPa).
Test Two - Transmission In 2 Range
This test checks pump output, line pressure and
pressure regulation. Use 100 psi Test Gauge C-3292
for this test.
(1) Leave vehicle in place on hoist and leave Test
Gauge C-3292 connected to accumulator port.
(2) Have helper start and run engine at 1000 rpm.
(3) Move transmission shift lever one detent rear-
ward from full forward position. This is 2 range.
(4) Move transmission throttle lever from full for-
ward to full rearward position and read pressure on
gauge.
(5) Line pressure should be 54-60 psi (372-414
kPa) with throttle lever forward and gradually
increase to 90-96 psi (621-662 kPa) as lever is moved
rearward.
Test Three - Transmission In D Range Third Gear
This test checks pressure regulation and condition
of the clutch circuits. Both test gauges are required
for this test.
(1) Turn OD switch off.
(2) Leave vehicle on hoist and leave Gauge C-3292
in place at accumulator port.
(3) Move Gauge C-3293-SP over to front servo port
for this test.
(4) Have helper start and run engine at 1600 rpm
for this test.
(5) Move transmission shift lever two detents rear-
ward from full forward position. This is D range.
(6) Read pressures on both gauges as transmission
throttle lever is gradually moved from full forward to
full rearward position:
²Line pressure at accumulator in D range third
gear, should be 54-60 psi (372-414 kPa) with throttle
lever forward and increase as lever is moved rear-
ward.
²Front servo pressure in D range third gear,
should be within 3 psi (21 kPa) of line pressure up to
kickdown point.
Test Four - Transmission In Reverse
This test checks pump output, pressure regulation
and the front clutch and rear servo circuits. Use 300
psi Test Gauge C-3293-SP for this test.
(1) Leave vehicle on hoist and leave gauge C-3292
in place at accumulator port.
(2) Move 300 psi Gauge C-3293-SP back to rear
servo port.
Fig. 9 Pressure Test Port Locations
1 - REAR SERVO TEST PORT
2 - GOVERNOR TEST PORT
3 - ACCUMULATOR TEST PORT
4 - FRONT SERVO TEST PORT
5 - OVERDRIVE CLUTCH TEST PORT
21 - 142 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)

(3) Have helper start and run engine at 1600 rpm
for test.
(4)
Move transmission shift lever four detents rear-
ward from full forward position. This is Reverse range.
(5) Move transmission throttle lever fully forward
then fully rearward and note reading at Gauge
C-3293-SP.
(6) Pressure should be 145 - 175 psi (1000-1207
kPa) with throttle lever forward and increase to 230 -
280 psi (1586-1931 kPa) as lever is gradually moved
rearward.
Test Five - Governor Pressure
This test checks governor operation by measuring
governor pressure response to changes in vehicle
speed. It is usually not necessary to check governor
operation unless shift speeds are incorrect or if the
transmission will not downshift. The test should be
performed on the road or on a hoist that will allow
the rear wheels to rotate freely.
(1) Move 100 psi Test Gauge C-3292 to governor
pressure port.
(2) Move transmission shift lever two detents rear-
ward from full forward position. This is D range.
(3) Have helper start and run engine at curb idle
speed. Then firmly apply service brakes so wheels
will not rotate.
(4) Note governor pressure:
²
Governor pressure should be no more than 20.6
kPa (3 psi) at curb idle speed and wheels not rotating.
²If pressure exceeds 20.6 kPa (3 psi), a fault
exists in governor pressure control system.
(5) Release brakes, slowly increase engine speed,
and observe speedometer and pressure test gauge (do
not exceed 30 mph on speedometer). Governor pres-
sure should increase in proportion to vehicle speed.
Or approximately 6.89 kPa (1 psi) for every 1 mph.
(6) Governor pressure rise should be smooth and
drop back to no more than 20.6 kPa (3 psi), after
engine returns to curb idle and brakes are applied to
prevent wheels from rotating.
(7)
Compare results of pressure test with analysis
chart.
Test Six - Transmission In Overdrive Fourth Gear
This test checks line pressure at the overdrive
clutch in fourth gear range. Use 300 psi Test Gauge
C-3293-SP for this test. The test should be performed
on the road or on a chassis dyno.
(1)
Remove tachometer; it is not needed for this test.
(2) Move 300 psi Gauge to overdrive clutch pres-
sure test port. Then remove other gauge and reinstall
test port plug.
(3) Lower vehicle.
(4) Turn OD switch on.(5) Secure test gauge so it can be viewed from
drivers seat.
(6) Start engine and shift into D range.
(7) Increase vehicle speed gradually until 3-4 shift
occurs and note gauge pressure.
(8) Pressure should be 524-565 kPa (76-82 psi)
with closed throttle and increase to 690-896 kPa
(100-130 psi) at 1/2 to 3/4 throttle. Note that pres-
sure can increase to around 965 kPa (140 psi) at full
throttle.
(9) Return to shop or move vehicle off chassis
dyno.
PRESSURE TEST ANALYSIS CHART
TEST CONDITION INDICATION
Line pressure OK during
any one testPump and regulator
valve OK
Line pressure OK in R
but low in D, 2, 1Leakage in rear clutch
area (seal rings, clutch
seals)
Pressure low in D Fourth
Gear RangeOverdrive clutch piston
seal, or check ball
problem
Pressure OK in 1, 2 but
low in D3 and RLeakage in front clutch
area
Pressure OK in 2 but low
in R and 1Leakage in rear servo
Front servo pressure in 2 Leakage in servo; broken
servo ring or cracked
servo piston
Pressure low in all
positionsClogged filter, stuck
regulator valve, worn or
faulty pump, low oil level
Governor pressure too
high at idle speedGovernor pressure
solenoid valve system
fault. Refer to diagnostic
book.
Governor pressure low at
all mph figuresFaulty governor pressure
solenoid, transmission
control module, or
governor pressure
sensor
Lubrication pressure low
at all throttle positionsClogged fluid cooler or
lines, seal rings leaking,
worn pump bushings,
pump, clutch retainer, or
clogged filter.
Line pressure high Output shaft plugged,
sticky regulator valve
Line pressure low Sticky regulator valve,
clogged filter, worn pump
DRAUTOMATIC TRANSMISSION - 48RE 21 - 143
AUTOMATIC TRANSMISSION - 48RE (Continued)

sure curve is higher than normal to make the
transmission shift at normal speeds and sooner. The
PCM uses a temperature sensor in the transmission
oil sump to determine when low temperature gover-
nor pressure is needed.
NORMAL OPERATION
Normal operation is refined through the increased
computing power of the PCM and through access to
data on engine operating conditions provided by the
PCM that were not available with the previous
stand-alone electronic module. This facilitated the
development of a load adaptive shift strategy - the
ability to alter the shift schedule in response to vehi-
cle load condition. One manifestation of this capabil-
ity is grade9hunting9prevention - the ability of the
transmission logic to delay an upshift on a grade if
the engine does not have sufficient power to main-
tain speed in the higher gear. The 3-2 downshift and
the potential for hunting between gears occurs with a
heavily loaded vehicle or on steep grades. When
hunting occurs, it is very objectionable because shifts
are frequent and accompanied by large changes in
noise and acceleration.
WIDE OPEN THROTTLE OPERATION
In wide-open throttle (WOT) mode, adaptive mem-
ory in the PCM assures that up-shifts occur at the
preprogrammed optimum speed. WOT operation is
determined from the throttle position sensor, which
is also a part of the emission control system. The ini-
tial setting for the WOT upshift is below the opti-
mum engine speed. As WOT shifts are repeated, the
PCM learns the time required to complete the shifts
by comparing the engine speed when the shifts occur
to the optimum speed. After each shift, the PCM
adjusts the shift point until the optimum speed is
reached. The PCM also considers vehicle loading,
grade and engine performance changes due to high
altitude in determining when to make WOT shifts. It
does this by measuring vehicle and engine accelera-
tion and then factoring in the shift time.
TRANSFER CASE LOW RANGE OPERATION
On four-wheel drive vehicles operating in low
range, the engine can accelerate to its peak more
rapidly than in Normal range, resulting in delayed
shifts and undesirable engine9flare.9The low range
governor pressure curve is also higher than normal
to initiate upshifts sooner. The PCM compares elec-
tronic vehicle speed signal used by the speedometer
to the transmission output shaft speed signal to
determine when the transfer case is in low range.REMOVAL
(1) Hoist and support vehicle on safety stands.
(2) Remove transmission fluid pan and filter.
(3) Disengage wire connectors from pressure sen-
sor and solenoid (Fig. 78).
(4) Remove screws holding pressure solenoid
retainer to governor body.
(5) Separate solenoid retainer from governor (Fig.
79).
Fig. 78 Governor Solenoid And Pressure Sensor
1 - PRESSURE SENSOR
2 - PRESSURE SOLENOID
3 - GOVERNOR
Fig. 79 Pressure Solenoid Retainer
1 - PRESSURE SOLENOID RETAINER
2 - GOVERNOR
DRAUTOMATIC TRANSMISSION - 48RE 21 - 199
ELECTRONIC GOVERNOR (Continued)

STATOR
Torque multiplication is achieved by locking the
stator's over-running clutch to its shaft (Fig. 234).
Under stall conditions the turbine is stationary and
the oil leaving the turbine blades strikes the face of
the stator blades and tries to rotate them in a coun-
terclockwise direction. When this happens the over-
running clutch of the stator locks and holds the
stator from rotating. With the stator locked, the oil
strikes the stator blades and is redirected into a
ªhelpingº direction before it enters the impeller. This
circulation of oil from impeller to turbine, turbine to
stator, and stator to impeller, can produce a maxi-
mum torque multiplication of about 1.75:1. As the
turbine begins to match the speed of the impeller, the
fluid that was hitting the stator in such as way as to
cause it to lock-up is no longer doing so. In this con-
dition of operation, the stator begins to free wheel
and the converter acts as a fluid coupling.
TORQUE CONVERTER CLUTCH (TCC)
The torque converter clutch is hydraulically
applied or released when fluid is feed or vented from
the hydraulic circuit by the torque converter control
(TCC) solenoid on the valve body. The torque con-
verter clutch is controlled by the Powertrain Control
Module (PCM). The torque converter clutch engages
in FOURTH gear, and in THIRD gear under various
conditions, such as when the O/D switch is OFF, orwhen the vehicle is cruising on a level surface after
the vehicle has warmed up. The torque converter
clutch can also be engaged in the MANUAL SEC-
OND gear position if high transmission temperatures
are sensed by the PCM. The torque converter clutch
may disengage momentarily when an increase in
engine load is sensed by the PCM, such as when the
vehicle begins to go uphill or the throttle pressure is
increased.
REMOVAL
(1) Remove transmission and torque converter
from vehicle.
(2) Place a suitable drain pan under the converter
housing end of the transmission.
CAUTION: Verify that transmission is secure on the
lifting device or work surface, the center of gravity
of the transmission will shift when the torque con-
verter is removed creating an unstable condition.
The torque converter is a heavy unit. Use caution
when separating the torque converter from the
transmission.
(3) Pull the torque converter forward until the cen-
ter hub clears the oil pump seal.
(4) Separate the torque converter from the trans-
mission.
INSTALLATION
Check converter hub and drive notches for sharp
edges, burrs, scratches, or nicks. Polish the hub and
notches with 320/400 grit paper or crocus cloth if nec-
essary. The hub must be smooth to avoid damaging
the pump seal at installation.
(1) Lubricate oil pump seal lip with transmission
fluid.
(2) Place torque converter in position on transmis-
sion.
CAUTION: Do not damage oil pump seal or bushing
while inserting torque converter into the front of the
transmission.
(3) Align torque converter to oil pump seal open-
ing.
(4) Insert torque converter hub into oil pump.
(5) While pushing torque converter inward, rotate
converter until converter is fully seated in the oil
pump gears.
Fig. 234 Stator Operation
1 - DIRECTION STATOR WILL FREE WHEEL DUE TO OIL
PUSHING ON BACKSIDE OF VANES
2 - FRONT OF ENGINE
3 - INCREASED ANGLE AS OIL STRIKES VANES
4 - DIRECTION STATOR IS LOCKED UP DUE TO OIL PUSHING
AGAINST STATOR VANES
21 - 260 AUTOMATIC TRANSMISSION - 48REDR
TORQUE CONVERTER (Continued)

OPERATION
The converter impeller (Fig. 123) (driving member),
which is integral to the converter housing and bolted
to the engine drive plate, rotates at engine speed.
The converter turbine (driven member), which reacts
from fluid pressure generated by the impeller, rotates
and turns the transmission input shaft.
TURBINE
As the fluid that was put into motion by the impel-
ler blades strikes the blades of the turbine, some of
the energy and rotational force is transferred into the
turbine and the input shaft. This causes both of them
(turbine and input shaft) to rotate in a clockwise
direction following the impeller. As the fluid is leav-
ing the trailing edges of the turbine's blades it con-
tinues in a ªhinderingº direction back toward the
impeller. If the fluid is not redirected before it strikes
the impeller, it will strike the impeller in such a
direction that it would tend to slow it down.
STATOR
Torque multiplication is achieved by locking the
stator's over-running clutch to its shaft (Fig. 124).
Under stall conditions (the turbine is stationary), the
oil leaving the turbine blades strikes the face of the
stator blades and tries to rotate them in a counter-
clockwise direction. When this happens the over-run-ning clutch of the stator locks and holds the stator
from rotating. With the stator locked, the oil strikes
the stator blades and is redirected into a ªhelpingº
direction before it enters the impeller. This circula-
tion of oil from impeller to turbine, turbine to stator,
and stator to impeller, can produce a maximum
torque multiplication of about 2.4:1. As the turbine
begins to match the speed of the impeller, the fluid
that was hitting the stator in such as way as to
cause it to lock-up is no longer doing so. In this con-
dition of operation, the stator begins to free wheel
and the converter acts as a fluid coupling.
TORQUE CONVERTER CLUTCH (TCC)
In a standard torque converter, the impeller and
turbine are rotating at about the same speed and the
stator is freewheeling, providing no torque multipli-
cation. By applying the turbine's piston and friction
material to the front cover, a total converter engage-
ment can be obtained. The result of this engagement
is a direct 1:1 mechanical link between the engine
and the transmission.
The clutch can be engaged in second, third, fourth,
and fifth (if appicable) gear ranges depending on
overdrive control switch position. If the overdrive
control switch is in the normal ON position, the
clutch will engage after the shift to fourth gear. If the
Fig. 123 Torque Converter Fluid Operation - Typical
1 - APPLY PRESSURE 3 - RELEASE PRESSURE
2 - THE PISTON MOVES SLIGHTLY FORWARD 4 - THE PISTON MOVES SLIGHTLY REARWARD
DRAUTOMATIC TRANSMISSION - 45RFE/545RFE 21 - 403
TORQUE CONVERTER (Continued)