Pcm DODGE RAM 2003 Service Repair Manual

Normal calibration will be performed when sump
temperature is above 50 degrees F, or in the absence
of sump temperature data, after the first 10 minutes
of vehicle operation. Calibration of the pressure
transducer offset occurs each time the output shaft
speed falls below 200 RPM. Calibration shall be
repeated each 3 seconds the output shaft speed is
below 200 RPM. A 0.5 second pulse of 95% duty cycle
is applied to the governor pressure solenoid valve
and the transducer output is read during this pulse.
Averaging of the transducer signal is necessary to
reject electrical noise.
Under cold conditions (below 50 degrees F sump),
the governor pressure solenoid valve response may
be too slow to guarantee 0 psi during the 0.5 second
calibration pulse. Calibration pulses are continued
during this period, however the transducer output
valves are discarded. Transducer offset must be read
at key-on, under conditions which promote a stable
reading. This value is retained and becomes the off-
set during the9cold9period of operation.
GOVERNOR PRESSURE SOLENOID VALVE
The inlet side of the solenoid valve is exposed to
normal transmission line pressure. The outlet side of
the valve leads to the valve body governor circuit.
The solenoid valve regulates line pressure to pro-
duce governor pressure. The average current sup-
plied to the solenoid controls governor pressure. One
amp current produces zero kPa/psi governor pres-
sure. Zero amps sets the maximum governor pres-
sure.
The powertrain control module (PCM) turns on the
trans control relay which supplies electrical power to
the solenoid valve. Operating voltage is 12 volts
(DC). The PCM controls the ground side of the sole-
noid using the governor pressure solenoid control cir-
cuit.
GOVERNOR PRESSURE SENSOR
The sensor output signal provides the necessary
feedback to the PCM. This feedback is needed to ade-
quately control governor pressure.
GOVERNOR BODY AND TRANSFER PLATE
The transfer plate channels line pressure to the
solenoid valve through the governor body. It also
channels governor pressure from the solenoid valve
to the governor circuit. It is the solenoid valve that
develops the necessary governor pressure.
GOVERNOR PRESSURE CURVES
LOW TRANSMISSION FLUID TEMPERATURE
When the transmission fluid is cold the conven-
tional governor can delay shifts, resulting in higherthan normal shift speeds and harsh shifts. The elec-
tronically controlled low temperature governor pres-
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.
DRAUTOMATIC TRANSMISSION - 46RE 21 - 197
ELECTRONIC GOVERNOR (Continued)

OVERDRIVE CLUTCH
DESCRIPTION
The overdrive clutch (Fig. 132) is composed of the
pressure plate, clutch plates, holding discs, overdrive
piston retainer, piston, piston spacer, and snap-rings.
The overdrive clutch is the forwardmost component
in the transmission overdrive unit and is considered
a holding component. The overdrive piston retainer,
piston, and piston spacer are located on the rear of
the main transmission case.
NOTE: The number of discs and plates may vary
with each engine and vehicle combination.
OPERATION
To apply the clutch, pressure is applied between the
piston retainer and piston. The fluid pressure is pro-
vided by the oil pump, transferred through the control
valves and passageways, and enters the clutch through
passages at the lower rear portion of the valve body
area. With pressure applied between the piston retainer
and piston, the piston moves away from the piston
retainer and compresses the clutch pack. This action
applies the clutch pack, allowing torque to flow through
the intermediate shaft into the overdrive planetary gear
set. The overdrive clutch discs are attached to the over-
drive clutch hub while the overdrive clutch plates, reac-
tion plate, and pressure plate are lugged to the
overdrive housing. This allows the intermediate shaft totransfer the engine torque to the planetary gear and
overrunning clutch. This drives the planetary gear
inside the annulus, which is attached to the overdrive
clutch drum and output shaft, creating the desired gear
ratio. The waved snap-ring is used to cushion the appli-
cation of the clutch pack.
OVERDRIVE SWITCH
DESCRIPTION
The overdrive OFF (control) switch is located in
the shift lever arm (Fig. 133). The switch is a
momentary contact device that signals the PCM to
toggle current status of the overdrive function.
OPERATION
At key-on, overdrive operation is allowed. Pressing
the switch once causes the overdrive OFF mode to be
entered and the overdrive OFF switch lamp to be
illuminated. Pressing the switch a second time
causes normal overdrive operation to be restored and
the overdrive lamp to be turned off. The overdrive
OFF mode defaults to ON after the ignition switch is
cycled OFF and ON. The normal position for the con-
trol switch is the ON position. The switch must be in
this position to energize the solenoid and allow a 3-4
upshift. The control switch indicator light illuminates
only when the overdrive switch is turned to the OFF
position, or when illuminated by the transmission
control module.
Fig. 132 Overdrive Clutch
1 - REACTION PLATE 2 - PRESSURE PLATE
21 - 218 AUTOMATIC TRANSMISSION - 46REDR

OPERATION
The converter impeller (Fig. 255) (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. 256).
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 overrun-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)
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 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 con-
ditions, 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
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.
Fig. 255 Torque Converter Fluid Operation
1 - APPLY PRESSURE 3 - RELEASE PRESSURE
2 - THE PISTON MOVES SLIGHTLY FORWARD 4 - THE PISTON MOVES SLIGHTLY REARWARD
DRAUTOMATIC TRANSMISSION - 46RE 21 - 261
TORQUE CONVERTER (Continued)

TRANSMISSION
TEMPERATURE SENSOR
DESCRIPTION
Transmission fluid temperature readings are sup-
plied to the transmission control module by the ther-
mistor (Fig. 266). The temperature readings are used
to control engagement of the fourth gear overdrive
clutch, the converter clutch, and governor pressure.
Normal resistance value for the thermistor at room
temperature is approximately 2000 ohms.
The thermistor is part of the governor pressure
sensor assembly and is immersed in transmission
fluid at all times.
OPERATION
The PCM prevents engagement of the converter
clutch and overdrive clutch, when fluid temperature
is below approximately 10ÉC (50ÉF).
If fluid temperature exceeds 126ÉC (260ÉF), the
PCM causes a 4-3 downshift and engage the con-
verter clutch. Engagement is according to the third
gear converter clutch engagement schedule.
The overdrive OFF lamp in the instrument panel
illuminates when the shift back to third occurs. The
transmission will not allow fourth gear operation
until fluid temperature decreases to approximately
110ÉC (230ÉF).
VALVE BODY
DESCRIPTION
The valve body consists of a cast aluminum valve
body, a separator plate, and transfer plate. The valve
body contains valves and check balls that control
fluid delivery to the torque converter clutch, bands,
and frictional clutches. The valve body contains the
following components (Fig. 267), (Fig. 268), (Fig.
269), and (Fig. 270):
²Regulator valve
²Regulator valve throttle pressure plug
²Line pressure plug and sleeve
²Kickdown valve
²Kickdown limit valve
²1-2 shift valve
²1-2 control valve
²2-3 shift valve
²2-3 governor plug
²3-4 shift valve
²3-4 timing valve
²3-4 quick fill valve
²3-4 accumulator
²Throttle valve
²Throttle pressure plug
²Switch valve
²Manual valve
²Converter clutch lock-up valve
²Converter clutch lock-up timing Valve
²Shuttle valve
²Shuttle valve throttle plug
²Boost Valve
²10 check balls
By adjusting the spring pressure acting on the reg-
ulator valve, transmission line pressure can be
adjusted.
Fig. 266 Governor Pressure Sensor
1 - GOVERNOR BODY
2 - GOVERNOR PRESSURE SENSOR/TRANSMISSION FLUID
TEMPERATURE THERMISTOR
DRAUTOMATIC TRANSMISSION - 46RE 21 - 267

3-4 SHIFT VALVE
The PCM energizes the overdrive solenoid during
the 3-4 upshift (Fig. 283). This causes the solenoid
check ball to close the vent port allowing line pres-
sure 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 (Fig. 284). 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.
3-4 TIMING VALVE
The 3-4 timing valve is moved by line pressure
coming through the 3-4 shift valve (Fig. 284). After
the shift, the timing valve holds the 2-3 shift valve in
an upshift position. The purpose is to prevent the 2-3
valve from downshifting before the 3-4 valve (Fig.
283).
3-4 QUICK FILL VALVE
The 3-4 quick fill valve provides faster engagement
of the overdrive clutch during 3-4 upshifts. The valve
temporarily bypasses the clutch piston feed orifice at
the start of a 3-4 upshift (Fig. 283). This exposes a
larger passage into the piston retainer resulting in a
much faster clutch fill and apply sequence. The quick
fill valve does not bypass the regular clutch feed ori-
fice throughout the 3-4 upshift. Instead, once a pre-
determined pressure develops within the clutch, the
valve closes the bypass (Fig. 284). Clutch fill is then
completed through the regular feed orifice.
Fig. 283 3-4 Shift Valve Before Shift
Fig. 284 3-4 Shift Valve After Shift
DRAUTOMATIC TRANSMISSION - 46RE 21 - 281
VALVE BODY (Continued)

MANUAL VALVE
The manual valve (Fig. 288) is a relay valve. The
purpose of the manual valve is to direct fluid to the
correct circuit needed for a specific gear or driving
range. The manual valve, as the name implies, is
manually operated by the driver with a lever located
on the side of the valve body. The valve is connected
mechanically by either a cable or linkage to the gear-
shift mechanism. The valve is held in each of its
positions by a spring-loaded roller or ball that
engages the ªroostercombº of the manual valve lever.
CONVERTER CLUTCH LOCK-UP VALVE
The torque converter clutch (TCC) lock-up valve
controls the back (ON) side of the torque converter
clutch. When the PCM energizes the TCC solenoid to
engage the converter clutch piston, pressure is
applied to the TCC lock-up valve which moves to the
right and applies pressure to the torque converter
clutch.
CONVERTER CLUTCH LOCK-UP TIMING VALVE
The torque converter clutch (TCC) lock-up timing
valve is there to block any 4-3 downshift until the
TCC is completely unlocked and the clutch is disen-
gaged.
SHUTTLE VALVE
The assembly is contained in a bore in the valve
body above the shift valves. When the manual valve
is positioned in the Drive range, throttle pressure
acts on the throttle plug of the shuttle valve (Fig.
280) to move it against a spring, increasing the
spring force on the shuttle valve. During a part or
full throttle 1-2 upshift, the throttle plug is bottomed
by throttle pressure, holding the shuttle valve to the
right against governor pressure, and opening a
by±pass circuit. The shuttle valve controls the qual-
ity of the kickdown shift by restricting the rate of
fluid discharge from the front clutch and servo
release circuits. During a 3-2 kickdown, fluid dis-
charges through the shuttle by-pass circuit. When
the shuttle valve closes the by-pass circuit, fluid dis-
charge is restricted and controlled for the application
of the front band. During a 2-3 ªlift footº upshift, the
shuttle valve by-passes the restriction to allow full
fluid flow through the by-pass groove for a faster
release of the band.
Fig. 288 Manual Valve
DRAUTOMATIC TRANSMISSION - 46RE 21 - 285
VALVE BODY (Continued)

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 transmission
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 converter 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 And Serial Number
Location
1 - PART NUMBER
2 - BUILD DATE
3 - SERIAL NUMBER
21 - 314 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)

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
overdrive 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
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 - 320 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
NO LOW GEAR (MOVES
IN 2ND OR 3RD GEAR
ONLY)1. Governor Circuit Electrical Fault. 1. Test with DRBTscan tool and repair as
required.
2. Valve Body Malfunction. 2. Remove, clean and inspect. Look for
sticking 1-2 shift valve, 2-3 shift valve,
governor plug or broken springs.
3. Front Servo Piston Cocked in
Bore.3. Inspect servo and repair as required.
4. Front Band Linkage Malfunction 4. Inspect linkage and look for bind in
linkage.
NO KICKDOWN OR
NORMAL DOWNSHIFT1. Throttle Linkage Mis-adjusted. 1. Adjust linkage.
2. Accelerator Pedal Travel
Restricted.2. Verify floor mat is not under pedal, repair
worn accelerator cable or bent brackets.
3. Valve Body Hydraulic Pressures
Too High or Too Low Due to Valve
Body Malfunction or Incorrect
Hydraulic Control Pressure
Adjustments.3. Perform hydraulic pressure tests to
determine cause and repair as required.
Correct valve body pressure adjustments as
required.
4. Governor Circuit Electrical Fault. 4. Test with DRBTscan tool and repair as
required.
5. Valve Body Malfunction. 5. Perform hydraulic pressure tests to
determine cause and repair as required.
Correct valve body pressure adjustments as
required.
6. TPS Malfunction. 6. Replace sensor, check with DRBTscan
tool.
7. PCM Malfunction. 7. Check with DRBTscan tool and replace
if required.
8. Valve Body Malfunction. 8. Repair sticking 1-2, 2-3 shift valves,
governor plugs, 3-4 solenoid, 3-4 shift
valve, 3-4 timing valve.
STUCK IN LOW GEAR
(WILL NOT UPSHIFT)1. Throttle Linkage Mis-adjusted/
Stuck.1. Adjust linkage and repair linkage if worn
or damaged. Check for binding cable or
missing return spring.
2. Gearshift Linkage Mis-adjusted. 2. Adjust linkage and repair linkage if worn
or damaged.
3. Governor Component Electrical
Fault.3. Check operating pressures and test with
DRBTscan tool, repair faulty component.
4. Front Band Out of Adjustment. 4. Adjust Band.
5. Clutch or Servo Malfunction. 5. Air pressure check operation of clutches
and bands. Repair faulty component.
CREEPS IN NEUTRAL 1. Gearshift Linkage Mis-adjusted. 1. Adjust linkage.
2. Rear Clutch Dragging/Warped. 2. Disassemble and repair.
3. Valve Body Malfunction. 3. Perform hydraulic pressure test to
determine cause and repair as required.
DRAUTOMATIC TRANSMISSION - 48RE 21 - 329
AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
GROWLING, GRATING OR
SCRAPING NOISES1. Drive Plate Broken. 1. Replace.
2. Torque Converter Bolts Hitting
Dust Shield.2. Dust shield bent. Replace or repair.
3. Planetary Gear Set Broken/
Seized.3. Check for debris in oil pan and repair as
required.
4. Overrunning Clutch Worn/Broken. 4. Inspect and check for debris in oil pan.
Repair as required.
5. Oil Pump Components Scored/
Binding.5. Remove, inspect and repair as required.
6. Output Shaft Bearing or Bushing
Damaged.6. Remove, inspect and repair as required.
7. Clutch Operation Faulty. 7. Perform air pressure check and repair as
required.
8. Front and Rear Bands Mis-
adjusted.8. Adjust bands.
DRAGS OR LOCKS UP 1. Fluid Level Low. 1. Check and adjust level.
2. Clutch Dragging/Failed 2. Air pressure check clutch operation and
repair as required.
3. Front or Rear Band Mis-adjusted. 3. Adjust bands.
4. Case Leaks Internally. 4. Check for leakage between passages in
case.
5. Servo Band or Linkage
Malfunction.5. Air pressure check servo operation and
repair as required.
6. Overrunning Clutch Worn. 6. Remove and inspect clutch. Repair as
required.
7. Planetary Gears Broken. 7. Remove, inspect and repair as required
(look for debris in oil pan).
8. Converter Clutch Dragging. 8. Check for plugged cooler. Inspect pump
for excessive side clearance. Replace
pump as required.
NO 4-3 DOWNSHIFT 1. Circuit Wiring and/or Connectors
Shorted.1. Test wiring and connectors with test lamp
and volt/ohmmeter. Repair wiring as
necessary. Replace connectors and/or
harnesses as required.
2. PCM Malfunction. 2. Check PCM operation with DRBTscan
tool. Replace PCM only if faulty.
3. TPS Malfunction 3. Check TPS with DRBTscan tool at PCM.
4. Lockup Solenoid Not Venting. 4. Remove valve body and replace solenoid
assembly if plugged or shorted.
5. Overdrive Solenoid Not Venting. 5. Remove valve body and replace solenoid
if plugged or shorted.
6. Valve Body Valve Sticking. 6. Repair stuck 3-4 shift valve or lockup
timing valve.
DRAUTOMATIC TRANSMISSION - 48RE 21 - 331
AUTOMATIC TRANSMISSION - 48RE (Continued)