Transmission fluid level DODGE RAM 1500 1998 2.G Owner's Guide

OPERATION
Hydraulic pressure is provided for the power steer-
ing gear by the belt driven power steering pump (Fig.
1). The power steering pumps are constant flow rate
and displacement, vane-type pumps.
DIAGNOSIS AND TESTING - PUMP LEAKAGE
The pump is serviced as an assembly and should
not be disassembled. The plastic pump reservoir and
the reservoir o-rings can be replaced.
Check for leaks in the following areas:
²Pump shaft seal behind the pulley
²Pump to reservoir O-ring
²Reservoir cap
²Pressure and return lines
²Flow control valve fitting
STANDARD PROCEDURE
STANDARD PROCEDURE - POWER STEERING
PUMP - INITIAL OPERATION
WARNING: THE FLUID LEVEL SHOULD BE
CHECKED WITH ENGINE OFF TO PREVENT INJURY
FROM MOVING COMPONENTS.
CAUTION: MOPARTATF+4 is to be used in the
power steering system. No other power steering or
automatic transmission fluid is to be used in the
system. Damage may result to the power steeringpump and system if any other fluid is used, and do
not overfill.
Wipe filler cap clean, then check the fluid level.
The dipstick should indicateCOLDwhen the fluid is
at normal temperature.
(1) Turn steering wheel all the way to the left
(2) Fill the pump fluid reservoir to the proper level
and let the fluid settle for at least two (2) minutes.
(3) Raise the front wheels off the ground.
(4) Slowly turn the steering wheel lock-to-lock 20
times with the engine off while checking the fluid
level.
NOTE: For vehicles with long return lines or oil
coolers turn wheel 40 times.
(5) Start the engine. With the engine idling main-
tain the fluid level.
(6) Lower the front wheels and let the engine idle
for two minutes.
(7) Turn the steering wheel in both direction and
verify power assist and quiet operation of the pump.
If the fluid is extremely foamy or milky looking,
allow the vehicle to stand a few minutes and repeat
the procedure.
CAUTION: Do not run a vehicle with foamy fluid for
an extended period. This may cause pump damage.
STANDARD PROCEDURE - FLUSHING POWER
STEERING SYSTEM
Flushing is required when the power steering/hy-
draulic booster system fluid has become contami-
nated. Contaminated fluid in the steering/booster
system can cause seal deterioration and affect steer-
ing gear/booster spool valve operation.
(1) Raise the front end of the vehicle off the
ground until the wheels are free to turn.
(2) Remove the return line from the pump.
NOTE: If vehicle is equipped with a hydraulic
booster remove both return lines from the pump.
(3) Plug the return line port/ports at the pump.
(4) Position the return line/lines into a large con-
tainer to catch the fluid.
(5) While an assistant is filling the pump reservoir
start the engine.
(6) With the engine running at idle turn the wheel
back and forth.
NOTE: Do not contact or hold the wheel against the
steering stops.
(7) Run a quart of fluid through the system then
stop the engine and install the return line/lines.
Fig. 1 POWER STEERING PUMP
1 - 3.7L & 4.7L (6 GROOVE)
PHENOLIC (PLASTIC TYPE) PULLEY
1 - 5.7L,5.9L & 8.0L (7 GROOVE)
PHENOLIC (PLASTIC TYPE) PULLEY
1 - 5.9L DIESEL (8 GROOVE)
STEEL PULLEY
2 - PUMP ASSEMBLY
3 - RESERVOIR
4 - CAP
19 - 40 PUMPDR
PUMP (Continued)

FLUID
DESCRIPTION
The recommended fluid for the power steering sys-
tem is MopartATF +4.
MopartATF+4, when new is red in color. The
ATF+4 is dyed red so it can be identified from other
fluids used in the vehicle such as engine oil or anti-
freeze. The red color is not permanent and is not an
indicator of fluid condition, As the vehicle is driven,
the ATF+4 will begin to look darker in color and may
eventually become brown.THIS IS NORMAL.
ATF+4 also has a unique odor that may change with
age. Consequently, odor and color cannot be used to
indicate the fluid condition or the need for a fluid
change.
STANDARD PROCEDURE - POWER STEERING
FLUID LEVEL CHECKING
WARNING: FLUID LEVEL SHOULD BE CHECKED
WITH THE ENGINE OFF TO PREVENT PERSONAL
INJURY FROM MOVING PARTS.
CAUTION: MOPARTATF+4 is to be used in the
power steering system. No other power steering or
automatic transmission fluid is to be used in the
system. Damage may result to the power steering
pump and system if any other fluid is used, and do
not overfill.
The power steering fluid level can be viewed on the
dipstick attached to the filler cap. There are two
ranges listed on the dipstick, COLD and HOT. Before
opening power steering system, wipe the reservoir
filler cap free of dirt and debris. Remove the cap and
check the fluid level on its dipstick. When the fluid is
at normal ambient temperature, approximately 21ÉC
to 27ÉC (70ÉF to 80ÉF), the fluid level should read
between the minimum and maximum area of the cold
range. When the fluid is hot, fluid level is allowed to
read up to the highest end of the HOT range. Only
add fluid when the vehicle is cold.
Use only MopartATF+4Do not overfill the
power steering system.
FLUID COOLER
REMOVAL
(1) Drain and siphon the power steering fluid.
(2) Disconnect the return and supply hoses con-
nected to the power steering fluid cooler.
(3) Remove the mounting bracket bolts securing
the fluid cooler to the brace. (Fig. 4)& (Fig. 5)(4) Remove the fluid cooler from the vehicle.
INSTALLATION
(1) Install the fluid cooler to the vehicle.
(2) Install the mounting bracket bolts securing the
fluid cooler to the brace (Fig. 4)& (Fig. 5).
(3) Reclamp the return and supply hoses to the
power steering fluid cooler.
(4) Refill the power steering fluid (Refer to 19 -
STEERING/PUMP - STANDARD PROCEDURE).
Fig. 4 V6 & V8 P/S FLUID COOLER
1 - POWER STEERING FLUID COOLER
2 - MOUNTING BOLTS
Fig. 5 V10 & DIESEL P/S FLUID COOLER
1 - RADIATOR
2 - POWER STEERING HOSES
3 - MOUNTING BOLTS
4 - P/S FLUID COOLER
DRPUMP 19 - 43

DIAGNOSIS AND TESTING
LOW LUBRICANT LEVEL
A low transmission lubricant level is generally the
result of a leak, inadequate lubricant fill or an incor-
rect lubricant level check. Leaks can occur at the
mating surfaces of the gear case, adaptor or exten-
sion housing, or from the front/rear seals. A sus-
pected leak could also be the result of an overfill
condition.
Leaks at the rear of the extension or adapter hous-
ing will be from the housing oil seals. Leaks at com-
ponent mating surfaces will probably be the result of
inadequate sealer, gaps in the sealer, incorrect bolt
tightening or use of a non-recommended sealer.
A leak at the front of the transmission will be from
either the front bearing retainer or retainer seal.
Lubricant may be seen dripping from the clutch
housing after extended operation. If the leak is
severe, it may also contaminate the clutch disc caus-
ing the disc to slip, grab and or chatter.
A correct lubricant level check can only be made
when the vehicle is level. Also allow the lubricant to
settle for a minute or so before checking. These rec-
ommendations will ensure an accurate check and
avoid an underfill or overfill condition. Always check
the lubricant level after any addition of fluid to avoid
an incorrect lubricant level condition.
HARD SHIFTING
Hard shifting is usually caused by a low lubricant
level, improper or contaminated lubricants. The con-
sequence of using non-recommended lubricants is
noise, excessive wear, internal bind and hard shift-
ing. Substantial lubricant leaks can result in gear,
shift rail, synchro, and bearing damage. If a leak
goes undetected for an extended period, the first indi-
cations of component damage are usually hard shift-
ing and noise.
Shift component damage or damaged clutch pres-
sure plate or disc are additional probable causes of
increased shift effort. Worn/damaged pressure plate
or disc can cause incorrect release. If clutch problem
is advanced, gear clash during shifts can result.
Worn or damaged synchro rings can cause gear clash
when shifting into any forward gear. In some new or
rebuilt transmissions, new synchro rings may tend to
stick slightly causing hard or noisy shifts. In most
cases this condition will decline as the rings wear-in.
TRANSMISSION NOISE
Most manual transmissions make some noise dur-
ing normal operation. Rotating gears generate a mild
whine that is audible, but generally only at extreme
speeds.
Severe highly audible transmission noise is gener-
ally the initial indicator of a lubricant problem.
Insufficient, improper or contaminated lubricant will
promote rapid wear of gears, synchros, shift rails,
forks and bearings. The overheating caused by a
lubricant problem, can also lead to gear and bearing
damage.
REMOVAL
(1) Disconnect battery negative cable.
(2) Shift transmission into Neutral.
(3) Remove shift boot bezel screws and slide boot
upward on shift lever extension.
(4) Remove shift lever extension from the shift
tower and lever assembly.
(5) Raise vehicle on hoist.
(6) Remove skid plate, if equipped.
(7) Drain lubricant if transmission will be disas-
sembled for service.
(8) Mark propeller shaft/shafts and companion
flange yoke/yokes for installation reference and
remove propeller shaft/shafts.
(9) Disconnect harness from clips on transmission
housing.
(10) Remove transfer case linkage if equipped.
(11) Remove transfer case mounting nuts and
remove transfer case if equipped.
(12) Remove slave cylinder mounting nut and
remove cylinder (Fig. 2).
Fig. 2 SLAVE CYLINDER
1 - MOUNTING NUTS
2 - SLAVE CYLINDER
DRMANUAL TRANSMISSION - NV3500 21 - 3
MANUAL TRANSMISSION - NV3500 (Continued)

The driver selects a particular gear by moving the
shift lever to the desired gear position. This move-
ment moves the internal transmission shift compo-
nents to begin the shift sequence. As the shift lever
moves the selected shift rail, the shift fork attached
to that rail begins to move. The fork is positioned in
a groove in the outer circumference of the synchro-
nizer sleeve. As the shift fork moves the synchronizer
sleeve, the synchronizer begins to speed-up or slow
down the selected gear (depending on whether the
driver is up-shifting or down-shifting). The synchro-
nizer does this by having the synchronizer hub
splined to the mainshaft, or the countershaft in some
cases, and moving the blocker ring into contact with
the gear's friction cone. As the blocker ring and fric-
tion cone come together, the gear speed is brought up
or down to the speed of the synchronizer. As the two
speeds match, the splines on the inside of the syn-
chronizer sleeve become aligned with the teeth on
the blocker ring and the friction cone and eventually
will slide over the teeth, locking the gear to the
mainshaft, or countershaft, through the synchronizer.
DIAGNOSIS AND TESTING
LOW LUBRICANT LEVEL
A low transmission lubricant level is generally the
result of a leak, inadequate lubricant fill or an incor-
rect lubricant level check. A correct lubricant level
check can only be made when the vehicle is level.
Also allow the lubricant to settle for a minute or so
before checking. These recommendations will ensure
an accurate check and avoid an underfill or overfill
condition. Always check the lubricant level after any
addition of fluid to avoid an incorrect lubricant level
condition.
Leaks can occur at the mating surfaces of the gear
case, adaptor or extension housing, or from the front/
rear seals. A suspected leak could also be the result
of an overfill condition. Leaks at the rear of the
extension or adapter housing will be from the hous-
ing oil seals. Leaks at component mating surfaces
will probably be the result of inadequate sealer, gaps
in the sealer, incorrect bolt tightening or use of a
non-recommended sealer. A leak at the front of the
transmission will be from either the front bearing
retainer or retainer seal. Lubricant may be seen drip-
ping from the clutch housing after extended opera-
tion. If the leak is severe, it may also contaminate
the clutch disc causing the disc to slip, grab and or
chatter.
HARD SHIFTING
Hard shifting is usually caused by a low lubricant
level, improper or contaminated lubricants. The con-
sequence of using non-recommended lubricants isnoise, excessive wear, internal bind and hard shift-
ing. Substantial lubricant leaks can result in gear,
shift rail, synchro, and bearing damage. If a leak
goes undetected for an extended period, the first indi-
cations of component damage are usually hard shift-
ing and noise.
Component damage, incorrect clutch adjustment or
damaged clutch pressure plate or disc are additional
probable causes of increased shift effort. Incorrect
adjustment or a worn/damaged pressure plate or disc
can cause incorrect release. If clutch problem is
advanced, gear clash during shifts can result. Worn
or damaged synchro rings can cause gear clash when
shifting into any forward gear. In some new or
rebuilt transmissions, new synchro rings may tend to
stick slightly causing hard or noisy shifts. In most
cases this condition will decline as the rings wear-in.
TRANSMISSION NOISE
Most manual transmissions make some noise dur-
ing normal operation. Rotating gears generate a mild
whine that is audible, but generally only at extreme
speeds. Severe highly audible transmission noise is
generally the initial indicator of a lubricant problem.
Insufficient, improper or contaminated lubricant
will promote rapid wear of gears, synchros, shift
rails, forks and bearings. The overheating caused by
a lubricant problem, can also lead to gear breakage.
REMOVAL
(1) Shift transmission into Neutral.
(2) Remove shift boot screws from floorpan and
slide boot upward on the shift lever.
(3) Remove shift lever extension from shift tower
and lever assembly.
(4) Remove shift tower bolts (Fig. 2).
Fig. 2 SHIFT TOWER
1 - SHIFT TOWER
2 - SHIFTER
3 - BOLTS
21 - 44 MANUAL TRANSMISSION - NV4500DR
MANUAL TRANSMISSION - NV4500 (Continued)

IDENTIFICATION
The transmission has two identification tags
attached to the driver side upper clutch housing (Fig.
2). One tag provides the transmission part number.
The second tag provides sequencing and build date
information. The information on the tags are essen-
tial to correct parts ordering.
OPERATION
The driver selects a particular gear by moving the
shift lever to the desired gear position. As the shift
lever moves the selected shift rail, the shift fork
attached to that rail begins to move. The fork is posi-
tioned in a groove in the outer circumference of the
synchronizer sleeve. As the shift fork moves the syn-
chronizer sleeve, the synchronizer begins to speed-up
or slow down the selected gear (depending on
whether we are up-shifting or down-shifting). The
synchronizer does this by having the synchronizer
hub splined to the mainshaft or the countershaft in
some cases, and moving the blocker ring into contact
with the gear's friction cone. As the blocker ring and
friction cone come together, the gear speed is brought
up or down to the speed of the synchronizer. As the
two speeds match, the splines on the inside of the
synchronizer sleeve become aligned with the teeth on
the blocker ring and friction cone and eventually will
slide over the teeth, locking the gear to the main-
shaft or countershaft through the synchronizer.
DIAGNOSIS AND TESTING
LOW LUBRICANT LEVEL
A low transmission lubricant level is generally the
result of a leak, inadequate lubricant fill or an incor-
rect lubricant level check. A correct lubricant level
check can only be made when the vehicle is level.
Also allow the lubricant to settle for a minute or sobefore checking. These recommendations will ensure
an accurate check and avoid an underfill or overfill
condition. Always check the lubricant level after any
addition of fluid to avoid an incorrect lubricant level
condition.
Leaks can occur at the mating surfaces of the gear
case, adaptor or extension housing, or from the front/
rear seals. A suspected leak could also be the result
of an overfill condition. Leaks at the rear of the
extension or adapter housing will be from the hous-
ing oil seals. Leaks at component mating surfaces
will probably be the result of inadequate sealer, gaps
in the sealer, incorrect bolt tightening or use of a
non-recommended sealer. A leak at the front of the
transmission will be from either the front bearing
retainer or retainer seal. Lubricant may be seen drip-
ping from the clutch housing after extended opera-
tion. If the leak is severe, it may also contaminate
the clutch disc causing the disc to slip, grab and or
chatter.
HARD SHIFTING
Hard shifting is usually caused by a low lubricant
level, improper or contaminated lubricants. The con-
sequence of using non-recommended lubricants is
noise, excessive wear, internal bind and hard shift-
ing. Substantial lubricant leaks can result in gear,
shift rail, synchro, and bearing damage. If a leak
goes undetected for an extended period, the first indi-
cations of component damage are usually hard shift-
ing and noise.
Component damage, incorrect clutch adjustment or
damaged clutch pressure plate or disc are additional
probable causes of increased shift effort. Incorrect
adjustment or a worn/damaged pressure plate or disc
can cause incorrect release. If clutch problem is
advanced, gear clash during shifts can result. Worn
or damaged synchro rings can cause gear clash when
shifting into any forward gear. In some new or
rebuilt transmissions, new synchro rings may tend to
stick slightly causing hard or noisy shifts. In most
cases this condition will decline as the rings wear-in.
TRANSMISSION NOISE
Most manual transmissions make some noise dur-
ing normal operation. Rotating gears generate a mild
whine that is audible, but generally only at extreme
speeds. Severe highly audible transmission noise is
generally the initial indicator of a lubricant problem.
Insufficient, improper or contaminated lubricant
will promote rapid wear of gears, synchros, shift
rails, forks and bearings. The overheating caused by
a lubricant problem, can also lead to gear breakage.
REMOVAL
(1) Shift transmission into Neutral.
Fig. 2 IDENTIFICATION TAG LOCATION
1 - IDENTIFICATION TAGS
21 - 90 MANUAL TRANSMISSION - NV5600DR
MANUAL TRANSMISSION - NV5600 (Continued)

ADAPTER HOUSING SEAL
REMOVAL
(1) Raise and support vehicle.
(2) Mark propeller shaft and yokes for installation
reference and remove shaft.
(3) Remove the transfer case.
(4) Remove the adapter housing seal with a pry
tool or slide hammer with a screw.
INSTALLATION
(1) Install adapter housing seal with Installer and
Handle C-4171.
(2) Install transfer case.
(3) Install propeller shaft with reference marks
aligned.
(4) Check fluid level.
(5) Remove support and lower vehicle.
EXTENSION HOUSING SEAL
REMOVAL
(1) Mark propeller shaft and pinion yoke for
installation reference and remove the propeller shaft.
(2) Remove extension housing seal with a pry tool
or a slide hammer and screw.
(3) Remove extension housing bushing with
Remover 8155 (Fig. 97).
INSTALLATION
(1) Install extension housing bushing with
Installer 8156 and Handle C-4171 (Fig. 98).
(2) Install extension housing seal with Installer
8154 and Handle C-4171 (Fig. 99).
(3) Install propeller shaft with reference marks
aligned.
(4) Check and fill transmission.
Fig. 97 EXTENSION HOUSING BUSHING REMOVAL
1 - REMOVER
Fig. 98 Install Extension Housing Bushing
1 - HANDLE
2 - INSTALLER
3 - BUSHING
Fig. 99 EXTENSION HOUSING SEAL INSTALLER
1 - INSTALLER
2 - HANDLE
21 - 128 MANUAL TRANSMISSION - NV5600DR

AUTOMATIC TRANSMISSION - 48RE
TABLE OF CONTENTS
page page
AUTOMATIC TRANSMISSION - 48RE
DESCRIPTION........................132
OPERATION..........................134
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - AUTOMATIC
TRANSMISSION.....................140
DIAGNOSIS AND TESTING - PRELIMINARY . 140
DIAGNOSIS AND TESTING - ROAD
TESTING...........................140
DIAGNOSIS AND TESTING - HYDRAULIC
PRESSURE TEST....................141
DIAGNOSIS AND TESTING - AIR TESTING
TRANSMISSION CLUTCH AND BAND
OPERATION........................144
DIAGNOSIS AND TESTING - CONVERTER
HOUSING FLUID LEAK................144
DIAGNOSIS AND TESTING - DIAGNOSIS
CHARTS...........................145
STANDARD PROCEDURE - ALUMINUM
THREAD REPAIR.....................158
REMOVAL............................158
DISASSEMBLY........................160
CLEANING...........................166
INSPECTION.........................166
ASSEMBLY...........................166
INSTALLATION........................174
SCHEMATICS AND DIAGRAMS
HYDRAULIC SCHEMATICS.............176
SPECIFICATIONS
TRANSMISSION.....................189
SPECIAL TOOLS
RE TRANSMISSION..................191
ACCUMULATOR
DESCRIPTION........................193
OPERATION..........................193
INSPECTION.........................194
BANDS
DESCRIPTION........................194
OPERATION..........................194
ADJUSTMENTS
ADJUSTMENT - BANDS...............195
BRAKE TRANSMISSION SHIFT INTERLOCK
SYSTEM
DESCRIPTION........................196
OPERATION..........................196
DIAGNOSIS AND TESTING - BRAKE
TRANSMISSION SHIFT INTERLOCK......196
ADJUSTMENTS - BRAKE TRANSMISSION
SHIFT INTERLOCK...................196ELECTRONIC GOVERNOR
DESCRIPTION........................197
OPERATION..........................198
REMOVAL............................199
INSTALLATION........................200
EXTENSION HOUSING SEAL
REMOVAL............................201
INSTALLATION........................201
FLUID AND FILTER
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - EFFECTS OF
INCORRECT FLUID LEVEL.............201
DIAGNOSIS AND TESTING - CAUSES OF
BURNT FLUID.......................201
DIAGNOSIS AND TESTING - FLUID
CONTAMINATION....................202
STANDARD PROCEDURE
STANDARD PROCEDURE - FLUID LEVEL
CHECK............................202
STANDARD PROCEDURE - FLUID AND
FILTER REPLACEMENT...............203
STANDARD PROCEDURE - TRANSMISSION
FILL...............................204
FRONT CLUTCH
DESCRIPTION........................205
OPERATION..........................205
DISASSEMBLY........................205
INSPECTION.........................206
ASSEMBLY...........................207
FRONT SERVO
DESCRIPTION........................208
OPERATION..........................208
DISASSEMBLY........................209
CLEANING...........................209
INSPECTION.........................209
ASSEMBLY...........................209
GEARSHIFT CABLE
DIAGNOSIS AND TESTING - GEARSHIFT
CABLE.............................210
REMOVAL............................210
INSTALLATION........................211
ADJUSTMENTS
GEARSHIFT CABLE..................212
OIL PUMP
DESCRIPTION........................213
OPERATION..........................213
DISASSEMBLY........................214
CLEANING...........................214
INSPECTION.........................214
ASSEMBLY...........................214
21 - 130 AUTOMATIC TRANSMISSION - 48REDR

IDENTIFICATION
Transmission identification numbers are stamped
on the left side of the case just above the oil pan gas-
ket surface (Fig. 2). Refer to this information when
ordering replacement parts.
GEAR RATIOS
The 48RE gear ratios are:
1st.................................2.45:1
2nd................................1.45:1
3rd................................1.00:1
4th.................................0.69:1
Rev.................................2.20:1
OPERATION
The application of each driving or holding compo-
nent is controlled by the valve body based upon the
manual lever position, throttle pressure, and gover-
nor pressure. The governor pressure is a variable
pressure input to the valve body and is one of the
signals that a shift is necessary. First through fourth
gear are obtained by selectively applying and releas-
ing the different clutches and bands. Engine power is
thereby routed to the various planetary gear assem-
blies which combine with the overrunning clutch
assemblies to generate the different gear ratios. The
torque converter clutch is hydraulically applied and
is released when fluid is vented from the hydraulic
circuit by the torque converter control (TCC) solenoid
on the valve body. The torque converter clutch is con-
trolled 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, when 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 SECOND gear position if high trans-
mission temperatures are sensed by the PCM. The
torque converter clutch will 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. The torque con-
verter clutch feature increases fuel economy and
reduces the transmission fluid temperature.
Since the overdrive clutch is applied in fourth gear
only and the direct clutch is applied in all ranges
except fourth gear, the transmission operation for
park, neutral, and first through third gear will be
described first. Once these powerflows are described,
the third to fourth shift sequence will be described.
1 - TORQUE CONVERTER 10 - OVERDRIVE CLUTCH
2 - INPUT SHAFT 11 - DIRECT CLUTCH
3 - OIL PUMP 12 - PLANETARY GEAR
4 - FRONT BAND 13 - INTERMEDIATE SHAFT
5 - FRONT CLUTCH 14 - OVERDRIVE OVERRUNNING CLUTCH
6 - REAR CLUTCH 15 - DIRECT CLUTCH SPRING
7 - PLANETARIES 16 - OVERDRIVE PISTON RETAINER
8 - REAR BAND 17 - OIL PAN
9 - OVERRUNNING CLUTCH 18 - VALVE BODY
Fig. 2 Transmission Part Number And Serial
Number Location
1 - PART NUMBER
2 - BUILD DATE
3 - SERIAL NUMBER
21 - 134 AUTOMATIC TRANSMISSION - 48REDR
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)

(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)