1998 DODGE RAM 1500 Transmission fluid level

DIAGNOSIS AND TESTING - HYDRAULIC
PRESSURE TEST
An accurate tachometer and pressure test gauges
are required. Test Gauge C-3293-SP has a 300 psi
range and is used at all locations where pressures
exceed 100 psi.
Pressure Test Port Locations
Only two pressure ports are supplied on the trans-
mission case. The torque converter clutch apply and
release ports are located on the right side of the
transmission case (Fig. 2).
To determine the line pressure, there are two avail-
able methods. The DRBtscan tool can be used to
read line pressure from the line pressure sensor. The
second method is to install Line Pressure Adapter
8259 (Fig. 4) into the transmission case and then
install the pressure gauge and the original sensor
into the adapter. This will allow a comparison of the
DRBtreadings and the gauge reading to determine
the accuracy of the line pressure sensor. The DRBt
line pressure reading should match the gauge read-
ing within  10 psi.
In order to access any other pressure tap locations,
the transmission oil pan must be removed, the pres-
sure port plugs removed and Valve Body Pressure
Tap Adapter 8258-A (Fig. 5) installed. The extensions
supplied with Adapter 8258-A will allow the installa-
tion of pressure gauges to the valve body. Refer to
(Fig. 3) for correct pressure tap location identifica-
tion.
TEST PROCEDURE
All pressure readings should be taken with the
transmission fluid level full, transmission oil at the
normal operating temperature, and the engine at
1500 rpm. Check the transmission for proper opera-
tion in each gear position that is in question or if a
specific element is in question, check the pressure
readings in at least two gear positions that employ
that element. Refer to the Hydraulic Schematics at
the rear of this section to determine the correct pres-
sures for each element in a given gear position.
Fig. 2 Torque Converter Pressure Locations
1 - TCC RELEASE
2 - TO COOLER
3 - TCC APPLY
4 - FROM COOLER
5 - LINE PRESSURE SENSOR
Fig. 3 Pressure Tap Locations
Fig. 4 Line Pressure Adapter 8259
1 - LINE PRESSURE SENSOR PORT
2 - LINE PRESSURE SENSOR
3 - TOOL 8259
4 - PRESSURE TAP
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AUTOMATIC TRANSMISSION - 45RFE/545RFE (Continued)

FLUID AND FILTER
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - EFFECTS OF
INCORRECT FLUID LEVEL
A low fluid level allows the pump to take in air
along with the fluid. Air in the fluid will cause fluid
pressures to be low and develop slower than normal.
If the transmission is overfilled, the gears churn the
fluid into foam. This aerates the fluid and causing
the same conditions occurring with a low level. In
either case, air bubbles cause fluid overheating, oxi-
dation and varnish buildup which interferes with
valve and clutch operation. Foaming also causes fluid
expansion which can result in fluid overflow from the
transmission vent or fill tube. Fluid overflow can eas-
ily be mistaken for a leak if inspection is not careful.
DIAGNOSIS AND TESTING - CAUSES OF
BURNT FLUID
Burnt, discolored fluid is a result of overheating
which has three primary causes.
(1) Internal clutch slippage, usually caused by low
line pressure, inadequate clutch apply pressure, or
clutch seal failure.
(2) A result of restricted fluid flow through the
main and/or auxiliary cooler. This condition is usu-
ally the result of a faulty or improperly installed
drainback valve, a damaged main cooler, or severe
restrictions in the coolers and lines caused by debris
or kinked lines.
(3) Heavy duty operation with a vehicle not prop-
erly equipped for this type of operation. Trailer tow-
ing or similar high load operation will overheat the
transmission fluid if the vehicle is improperly
equipped. Such vehicles should have an auxiliary
transmission fluid cooler, a heavy duty cooling sys-
tem, and the engine/axle ratio combination needed to
handle heavy loads.
DIAGNOSIS AND TESTING - FLUID
CONTAMINATION
Transmission fluid contamination is generally a
result of:
²adding incorrect fluid
²failure to clean dipstick and fill tube when
checking level
²engine coolant entering the fluid
²internal failure that generates debris
²overheat that generates sludge (fluid break-
down)
²failure to replace contaminated converter after
repairThe use of non-recommended fluids can result in
transmission failure. The usual results are erratic
shifts, slippage, abnormal wear and eventual failure
due to fluid breakdown and sludge formation. Avoid
this condition by using recommended fluids only.
The dipstick cap and fill tube should be wiped
clean before checking fluid level. Dirt, grease and
other foreign material on the cap and tube could fall
into the tube if not removed beforehand. Take the
time to wipe the cap and tube clean before withdraw-
ing the dipstick.
Engine coolant in the transmission fluid is gener-
ally caused by a cooler malfunction. The only remedy
is to replace the radiator as the cooler in the radiator
is not a serviceable part. If coolant has circulated
through the transmission, an overhaul is necessary.
The torque converter should also be replaced when-
ever a failure generates sludge and debris. This is
necessary because normal converter flushing proce-
dures will not remove all contaminants.
STANDARD PROCEDURE
STANDARD PROCEDURE - FLUID LEVEL
CHECK
Low fluid level can cause a variety of conditions
because it allows the pump to take in air along with
the fluid. As in any hydraulic system, air bubbles
make the fluid spongy, therefore, pressures will be
low and build up slowly.
Improper filling can also raise the fluid level too
high. When the transmssion has too much fluid, the
geartrain churns up foam and cause the same condi-
tions which occur with a low fluid level.
In either case, air bubbles can cause overheating
and/or fluid oxidation, and varnishing. This can
interfere with normal valve, clutch, and accumulator
operation. Foaming can also result in fluid escaping
from the transmission vent where it may be mis-
taken for a leak.
After the fluid has been checked, seat the dipstick
fully to seal out water and dirt.
The transmission has a dipstick to check oil level.
It is located on the right side of the engine. Be sure
to wipe all dirt from dipstick handle before removing.
The torque converter fills in both the P (PARK)
and N (NEUTRAL) positions. Place the selector lever
in P (PARK) to be sure that the fluid level check is
accurate.The engine should be running at idle
speed for at least one minute, with the vehicle
on level ground.At normal operating temperature
(approximately 82 C. or 180 F.), the fluid level is cor-
rect if it is in the HOT region (cross-hatched area) on
the oil level indicator. The fluid level will be approx-
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imately at the upper COLD hole of the dipstick at
70É F fluid temperature.
NOTE: Engine and Transmission should be at nor-
mal operating temperature before performing this
procedure.
(1) Start engine and apply parking brake.
(2) Shift the transmission into DRIVE for approxi-
mately 2 seconds.
(3) Shift the transmission into REVERSE for
approximately 2 seconds.
(4) Shift the transmission into PARK.
(5) Hook up DRBtscan tool and select transmis-
sion.
(6) Select sensors.
(7) Read the transmission temperature value.
(8) Compare the fluid temperature value with the
chart. (Fig. 66)
(9) Adjust transmission fluid level shown on the
dipstick according to the chart.
NOTE: After adding any fluid to the transmission,
wait a minimum of 2 minutes for the oil to fully
drain from the fill tube into the transmission before
rechecking the fluid level.
(10) Check transmission for leaks.STANDARD PROCEDURE - FLUID AND FILTER
REPLACEMENT
For proper service intervals (Refer to LUBRICA-
TION & MAINTENANCE/MAINTENANCE SCHED-
ULES - DESCRIPTION).
REMOVAL
(1) Hoist and support vehicle on safety stands.
(2) Place a large diameter shallow drain pan
beneath the transmission pan.
(3) Remove bolts holding front and sides of pan to
transmission.
(4) Loosen bolts holding rear of pan to transmis-
sion.
(5) Slowly separate front of pan away from trans-
mission allowing the fluid to drain into drain pan.
(6) Hold up pan and remove remaining bolts hold-
ing pan to transmission.
(7) While holding pan level, lower pan away from
transmission.
(8) Pour remaining fluid in pan into drain pan.
(9) Remove screw holding filter to valve body (Fig.
67).
(10) Separate filter from valve body and oil pump
and pour fluid in filter into drain pan.
Fig. 66 Transmission Fluid Temperature Chart
DRAUTOMATIC TRANSMISSION - 45RFE/545RFE 21 - 367
FLUID AND FILTER (Continued)

(28) Install the number 2 bearing onto the under-
drive hub with outer race against the hub with petro-
leum jelly.
(29) Install the underdrive hub into the input
clutch retainer.
(30) Install the number 3 bearing into the over-
drive hub with the outer race against the hub with
petroleum jelly.
(31) Install the overdrive hub into the input clutch
retainer.
(32) Install the number 4 bearing into the reverse
hub with outer race against the hub with petroleum
jelly.
(33) Install the reverse hub into the input clutch
retainer.
(34) Install the complete reverse clutch pack.
(35) Install the reverse reaction plate and snap-
ring.
(36) Push up on reaction plate to allow reverse
clutch to move freely.
INPUT SPEED SENSOR
DESCRIPTION
The Input and Output Speed Sensors are two-wire
magnetic pickup devices that generate AC signals as
rotation occurs. They are mounted in the left side of
the transmission case and are considered primary
inputs to the Transmission Control Module (TCM).
OPERATION
The Input Speed Sensor provides information on
how fast the input shaft is rotating. As the teeth of
the input clutch hub pass by the sensor coil, an AC
voltage is generated and sent to the TCM. The TCM
interprets this information as input shaft rpm.
The Output Speed Sensor generates an AC signal
in a similar fashion, though its coil is excited by rota-
tion of the rear planetary carrier lugs. The TCM
interprets this information as output shaft rpm.
The TCM compares the input and output speed
signals to determine the following:
²Transmission gear ratio
²Speed ratio error detection
²CVI calculation
The TCM also compares the input speed signal and
the engine speed signal to determine the following:
²Torque converter clutch slippage
²Torque converter element speed ratio
REMOVAL
(1) Raise vehicle.
(2) Place a suitable fluid catch pan under the
transmission.(3) Remove the wiring connector from the input
speed sensor (Fig. 91).
(4) Remove the bolt holding the input speed sensor
to the transmission case.
(5) Remove the input speed sensor from the trans-
mission case.
INSTALLATION
(1) Install the input speed sensor into the trans-
mission case.
(2) Install the bolt to hold the input speed sensor
into the transmission case. Tighten the bolt to 11.9
N´m (105 in.lbs.).
(3) Install the wiring connector onto the input
speed sensor
(4) Verify the transmission fluid level. Add fluid as
necessary.
(5) Lower vehicle.
LINE PRESSURE (LP) SENSOR
DESCRIPTION
The TCM utilizes a closed-loop system to control
transmission line pressure. The system contains a
variable force style solenoid, the Pressure Control
Solenoid, mounted on the side of the solenoid and
pressure switch assembly. The solenoid is duty cycle
controlled by the TCM to vent the unnecessary line
pressure supplied by the oil pump back to the sump.
The system also contains a variable pressure style
sensor, the Line Pressure Sensor, which is a direct
input to the TCM. The line pressure solenoid moni-
tors the transmission line pressure and completes the
Fig. 91 Input Speed Sensor
1 - OUTPUT SPEED SENSOR
2 - LINE PRESSURE SENSOR
3 - INPUT SPEED SENSOR
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INPUT CLUTCH ASSEMBLY (Continued)

feedback loop to the TCM. The TCM uses this infor-
mation to adjust its control of the pressure control
solenoid to achieve the desired line pressure.
OPERATION
The TCM calculates the desired line pressure
based upon inputs from the transmission and engine.
The TCM calculates the torque input to the trans-
mission and uses that information as the primary
input to the calculation. The line pressure is set to a
predetermined value during shifts and when the
transmission is in the PARK and NEUTRAL posi-
tions. This is done to ensure consistent shift quality.
During all other operation, the actual line pressure is
compared to the desired line pressure and adjust-
ments are made to the pressure control solenoid duty
cycle.
REMOVAL
(1) Raise vehicle.
(2) Place a suitable fluid catch pan under the
transmission.
(3) Remove the wiring connector from the line
pressure sensor (Fig. 92).
(4) Remove the bolt holding the line pressure sen-
sor to the transmission case.
(5) Remove the line pressure sensor from the
transmission case.
INSTALLATION
(1) Install the line pressure sensor into the trans-
mission case.(2) Install the bolt to hold the line pressure sensor
into the transmission case. Tighten the bolt to 11.9
N´m (105 in.lbs.).
(3) Install the wiring connector onto the line pres-
sure sensor
(4) Verify the transmission fluid level. Add fluid as
necessary.
(5) Lower vehicle.
Fig. 92 Line Pressure Sensor
1 - OUTPUT SPEED SENSOR
2 - LINE PRESSURE SENSOR
3 - INPUT SPEED SENSOR
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LINE PRESSURE (LP) SENSOR (Continued)

CONVERTER CLUTCH REGULATOR VALVE
The converter clutch regulator valve is used to con-
trol the hydraulic pressure supplied to the back (ON)
side of the torque converter clutch.
TORQUE CONVERTER LIMIT VALVE
The torque converter limit valve serves to limit the
available line pressure to the torque converter clutch.
STANDARD PROCEDURE - OIL PUMP VOLUME
CHECK
Measuring the oil pump output volume will deter-
mine if sufficient oil flow to the transmission oil
cooler exists, and whether or not an internal trans-
mission failure is present.Verify that the transmission fluid is at the proper
level. Refer to the Fluid Level Check procedure in
this section. If necessary, fill the transmission to the
proper level with MopartATF +4, Automatic Trans-
mission Fluid.
(1) Disconnect theTo coolerline at the cooler
inlet and place a collecting container under the dis-
connected line.
CAUTION: With the fluid set at the proper level,
fluid collection should not exceed (1) quart or inter-
nal damage to the transmission may occur.
(2) Run the engineat 1800 rpm, with the shift
selector in neutral. Verify that the transmission fluid
temperature is below 104.5É C (220É F) for this test.
Fig. 99 Oil Pump Reaction Shaft
1 - PUMP HOUSING 4 - SEAL RING (5)
2 - SEAL 5 - REACTION SHAFT SUPPORT
3 - OIL FILTER SEAL 6 - PUMP VALVE BODY
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OIL PUMP (Continued)

(3) If one quart of transmission fluid is collected in
the container in 30 seconds or less, oil pump flow vol-
ume is within acceptable limits. If fluid flow is inter-
mittent, or it takes more than 30 seconds to collect
one quart of fluid, refer to the Hydraulic Pressure
tests in this section for further diagnosis.
(4) Re-connect theTo coolerline to the transmis-
sion cooler inlet.
(5) Refill the transmission to proper level.
DISASSEMBLY
(1) Remove the bolts holding the reaction shaft
support to the oil pump (Fig. 100).
(2) Remove the reaction shaft support from the oil
pump (Fig. 100).(3) Remove all bolts holding the oil pump halves
together (Fig. 100).
(4) Using suitable prying tools, separate the oil
pump sections by inserting the tools in the supplied
areas and prying the halves apart.
NOTE: The oil pump halves are aligned to each
other through the use of two dowels. Be sure to pry
upward evenly to prevent damage to the oil pump
components.
(5) Remove the screws holding the separator plate
onto the oil pump body (Fig. 101).
(6) Remove the separator plate from the oil pump
body (Fig. 101).
Fig. 100 Oil Pump Assembly
1 - PUMP HOUSING 4 - SEAL RING (5)
2 - SEAL 5 - REACTION SHAFT SUPPORT
3 - OIL FILTER SEAL 6 - PUMP VALVE BODY
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OIL PUMP (Continued)

INSTALLATION
(1) Install the output speed sensor into the trans-
mission case.
(2) Install the bolt to hold the output speed sensor
into the transmission case. Tighten the bolt to 11.9
N´m (105 in.lbs.).
(3) Install the wiring connector onto the output
speed sensor
(4) Verify the transmission fluid level. Add fluid as
necessary.
(5) Lower vehicle.
TOW/HAUL OVERDRIVE
SWITCH
DESCRIPTION
The tow/haul overdrive OFF (control) switch is
located in the shift lever arm (Fig. 106). 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 tow/haul overdrive OFF
mode to be entered and the Tow/Haul lamp to be illu-
minated. Pressing the switch a second time causesnormal overdrive operation to be restored and the
tow/haul lamp to be turned off. The tow/haul over-
drive OFF mode defaults to ON after the ignition
switch is cycled OFF and ON. The normal position
for the control 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 tow/haul overdrive switch
is turned to the OFF position, or when illuminated
by the transmission control module.
REMOVAL
(1) Using a plastic trim tool, remove the tow/haul
overdrive off switch retainer from the shift lever (Fig.
107).
Fig. 105 Output Speed Sensor
1 - OUTPUT SPEED SENSOR
2 - LINE PRESSURE SENSOR
3 - INPUT SPEED SENSOR
Fig. 106 Tow/Haul Overdrive Off Switch
Fig. 107 Tow/Haul Overdrive Off Switch Retainer
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OUTPUT SPEED SENSOR (Continued)