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ACTUATOR-THROTTLE VALVE
DESCRIPTION
On vehicles equipped with a Cummins diesel engine,
the transmission throttle valve cable has been replace
by the transmission throttle valve actuator (TTVA). The
TTVA consists of an electric DC motor, two potentiom-
eters, and a gear drive system. The TTVA is mechan-
ically connected to the transmission throttle valve in
the valve body by the “D” shaped opening in the bot-
tom of the TTVA shaft. Changes in the TTVA position
are therefore transferred to the throttle valve and
cause changes in the transmission throttle pressure.
REMOVAL
1. Remove the bolts (2) holding the transmission
throttle valve actuator (TTVA) (1) to the transmis-
sion case.
2. Allow the TTVA (1) to rotate clockwise away from
the transmission.
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3. Remove the wiring connector (2) from the TTVA
(1).
4. Lift the TTVA (1) straight upward and off the throttle
valve shaft (3).
INSTALLATION
1. Position the transmission throttle valve actuator
(TTVA) (1) over the throttle valve shaft (3).
2. Align the D-shaped opening in the bottom of the
TTVA to the throttle valve shaft and install the
TTVA onto the shaft.
3. Install the wiring connector (2) to the TTVA (1).
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4. Rotate the TTVA (1) to the transmission case and
install the bolts (2) to hold the TTVA to the trans-
mission.
5. Tighten the bolts to 8.5 Nꞏm (75 in.lbs.).
6. Initialize the TTVA (Refer to 21 - TRANSMISSION/
AUTOMATIC - 48RE/THROTTLE VALVE ACTUA-
TOR - ADJUSTMENTS).
ADJUSTMENTS
ADJUSTMENT
The Transmission Throttle Valve Actuator (TTVA) does not require any mechanical adjustments. All changes in throt-
tle valve position are controlled by the Engine Control Module (ECM).
The TTVA does require an initialization period after the actuator has beenremoved or replaced. After the actuator
has been removed or replaced, move the iginition to the ON position for thirty (30) seconds. This will allow the ECM
sufficient time to perform the internal calibration procedures to learn the TTVA’s current “zero” position. Once this is
done, check the ECM for diagnostic trouble codes (DTCs). If no DTCs are set relating to the TTVA, the TTVA is fully
calibrated and ready for use.
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CABLE-THROTTLE VALVE
DESCRIPTION
Transmission throttle valve cable (1) adjustment is
extremely important to proper operation. This adjust-
ment positions the throttle valve, which controls shift
speed, quality, and part-throttle downshift sensitivity.
If cable setting is too loose, early shifts and slippage
between shifts may occur. If the setting is too tight,
shifts may be delayed and part throttle downshifts may
be very sensitive.
The transmission throttlevalveisoperatedbyacam
on the throttle lever. The throttle lever is operated by
an adjustable cable (3). The cable is attached to an
arm mounted on the throttle lever shaft. A retaining
clip (2) at the engine-end of the cable is removed to
provide for cable adjustment. The retaining clip is then
installedbackontothethrottlevalvecabletolockin
the adjustment.
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ADJUSTMENTS - THROTTLE VALVE CABLE
A correctly adjusted throttle valve cable (1) will cause
the throttle lever on the transmission to move simulta-
neously with the throttle body lever (3) from the idle
position. Proper adjustment will allow simultaneous
movement without causing the transmission throttle
lever to either move ahead of, or lag behind the lever
on the throttle body.
ADJUSTMENT VERIFICATION
1. Turn ignition key to OFF position.
2. Remove air cleaner.
3. Verify that lever on throttle body is at curb idle
position. Then verify that the transmission throttle
lever is also at idle (fully forward) position.
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4. Slide cable off attachment stud on throttle body
lever.
5. Compare position (B) of cable end to attachment
stud on throttle body lever:
Cable end and attachment stud should be
aligned (or centered on one another) to within 1
mm (0.039 in.) in either direction (B).
If cable end and attachment stud are misaligned
(off center), cable will have to be adjusted as
described in Throttle Valve Cable Adjustment
procedure.
6. Reconnect cable end to attachment stud. Then with
aid of a helper, observe movement of transmission
throttle lever and lever on throttle body.
If both levers move simultaneously from idle to
half-throttle and back to idle position, adjustment
is correct.
If transmission throttle lever moves ahead of, or
lags behind throttle body lever, cable adjustment
will be necessary. Or, if throttle body lever pre-
vents transmission lever from returning to closed
position, cable adjustment will be necessary.
ADJUSTMENT PROCEDURE
1. Turn ignition switch to OFF position.
2. Remove air cleaner if necessary.
3. Disconnect cable end (3) from attachment stud on
throttle lever (1).Carefully slide cable off stud.
Do not pry or pull cable off.
4. Verify that transmission throttle lever is in fully
closed position. Then be sure lever on throttle body
is at curb idle position.
5. Pry the T.V. cable lock (A) into the UP position.
This will unlock the cable and allow for readjust-
ment.
6. Apply just enough tension on the T.V. cable (B) to
remove any slack in the cable.Pulling too tight
will cause the T.V. lever on the transmission to
move out of its idle position, which will result
in an incorrect T.V. cable adjustment.Slide the
sheath of the T.V. cable (D) back and forth until the
centerlines of the T.V. cable end (B) and the throttle
bell crank lever (C) are aligned within one millime-
ter (1mm).
7. While holding the T.V. cable in the set position
push the T.V. cable lock (A) into the down position.
This will lock the present T.V. cable adjustment.
NOTE:Besurethatasthecableispulledforward
and centered on the throttle lever stud, the cable
housing moves smoothly with the cable. Due to
the angle at which the cable housing enters the spring housing, the cable housing may bind slightly and
create an incorrect adjustment.
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8. Reconnect the T.V. cable (B) to the throttle bellcrank lever (C).
9. Check cable adjustment. Verify transmission throttle lever and lever on throttle body move simultaneously.
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CONVERTER-TORQUE
DESCRIPTION
The torque converter is a hydraulic device that cou-
ples the engine crankshaft to the transmission. The
torque converter consists of an outer shell with an
internal turbine (1), a stator (4), an overrunning clutch,
an impeller (2), and an electronically applied converter
clutch (6). The converterclutch provides reduced
engine speed and greater fuel economy when
engaged. Clutch engagement also provides reduced
transmission fluid temperatures. The torque converter
hub drives the transmission oil (fluid) pump.
The torque converter is a sealed, welded unit that is
not repairable and is serviced as an assembly.
CAUTION: The torque converter must be replaced
if a transmission failure resulted in large amounts
of metal or fiber contamination in the fluid.