1994 JEEP CHEROKEE automatic transmission

FIRSTÐTHIRDÐREVERSE GEAR COMPONENTS
First, third and reverse gear components are out-
lined in Figure 6.
The input shaft is meshed with the direct clutch
hub and the forward clutch drum. These elements ro-
tate as a unit. The forward clutch hub rotates as a
unit with the front planetary ring gear. The direct
clutch drum is meshed with the forward end of the
planetary sun gear.
The second brake hub serves as the outer race of
one-way clutch No. 1. The clutch inner race is locked
with the front/rear sun gear. The inner race of one-way clutch No. 2 is splined to the transmission case
and is locked. The outer race rotates as a unit with
the rear planetary carrier.
The rear planetary ring gear is splined to the out-
put shaft. The front planetary carrier and rear car-
rier ring gear are meshed and rotate as a unit with
the output shaft.
GEARTRAIN OPERATION AND APPLICATION
CHARTS
Operation and application of the first through
fourth and reverse gear elements are outlined in the
function and application charts.
Fig. 6 First, Third And Reverse Gear Components
Fig. 7 Component Function Chart
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The Component Function Chart (Fig. 7) describes
basic function of various geartrain elements. The
Component Application Chart (Fig. 8) indicates
which elements (including valve body solenoids), are
applied in the various gear ranges.
HYDRAULIC SYSTEM
The basic hydraulic system consists of the oil
pump, valve body and solenoids and four hydraulic
accumulators. The oil pump provides the necessary
system lubrication and operating pressure.
The valve body controls application of the clutches,
brakes, second coast band and the torque converter
clutch. The valve body solenoids control sequencing
of the 1-2, 2-3 and 3-4 shift valves within the valve
body. The solenoids are activated by signals from the
transmission control module.
The accumulators are used in the clutch and brake
feed circuits to control initial apply pressure. Spring
loaded accumulator pistons modulate the initial
surge of apply pressure for smooth engagement.
OIL PUMP
A gear-type oil pump is used. The pump gears are
mounted in the pump body. The pump drive gear is
operated by the torque converter hub. Drive tangs on
the hub engage in drive slots in the drive gear.
TRANSMISSION VALVE BODY COMPONENTS
Transmission operating pressure is supplied to the
clutch and brake apply circuits through the transmis-
sion valve body. The valve body consists of an upper
body, lower body, separator plate and upper andlower gaskets (Fig. 9). The various spool valves,
sleeves, plugs and springs are located within the two
body sections.
The manual valve, 1-2 shift valve, primary regula-
tor valve, accumulator control valve, check balls, so-
lenoids and oil strainers are located in the lower
body section (Fig. 10). The remaining control and
shift valves plus check balls and one additional oil
strainer are located in the upper body section (Fig.
11).
Fig. 8 Component Application Chart
Fig. 9 Two-Section Transmission Valve Body
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Manual Valve
The manual valve is operated by the gearshift link-
age. The valve diverts fluid to the apply circuits ac-
cording to shift lever position.
Primary Regulator Valve
The primary regulator valve (Fig. 13) modulates
line pressure to the clutches and brakes according to
engine load. The valve is actuated by throttle valve
pressure.
During high load operation, the valve increases line
pressure to maintain positive clutch and brake en-gagement. At light load, the valve decreases line
pressure just enough to maintain smooth engage-
ment.
Throttle Valve and Downshift Plug
The throttle valve and downshift plug (Fig. 14) con-
trol throttle pressure to the primary regulator valve.
The downshift plug and throttle valve are operated
by the throttle valve cam and throttle cable in re-
sponse to engine throttle position. Throttle valve
pressure is also modulated by the cut-back valve in
second, third and fourth gear ranges.
Fig. 11 Lower Body Components
Fig. 10 Upper Body Components
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Cut-Back Valve
The cut-back valve (Fig. 15) helps prevent exces-
sive pump pressure buildup in second, third and
fourth gear. The valve is actuated by throttle pres-
sure and by line pressure from the second brake. The
valve also helps regulate line pressure by controlling
the amount of cut-back pressure to the throttle valve.Secondary Regulator Valve
The secondary regulator valve (Fig. 16) regulates
converter clutch and transmission lubrication pres-
sure. When primary regulator valve pressure exceeds
requirements for clutch engagement or transmission
lubrication, the secondary regulator valve is moved
Fig. 12 Manual Valve
Fig. 13 Primary Regulator Valve
Fig. 14 Throttle Valve And Downshift Plug
Fig. 15 Cut-Back Valve
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upward exposing the drain port. Excess pressure
then bleeds off as needed. As pressure drops, spring
tension moves the valve downward closing the drain
port.
Converter Clutch Relay Valve
The relay valve (Fig. 17) controls fluid flow to the
converter clutch. The valve is operated by line pres-
sure from the 1-2 shift valve and is controlled by so-
lenoid valve number three.1-2 Shift Valve
The 1-2 shift valve (Fig. 18) controls 1-2 upshifts
and downshifts. The valve is operated by the No. 2
valve body solenoid and line pressure from the man-
ual valve, second coast modulator valve and the 2-3
shift valve.
When the transmission control module deactivates
the solenoid, line pressure at the top of the valve
moves the valve down closing the second brake accu-
mulator feed port. As the solenoid is activated and
Fig. 16 Secondary Regulator Valve
Fig. 18 1-2 Shift Valve
Fig. 17 Converter Clutch Relay Valve
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the drain port opens, spring force moves the valve up
exposing the second brake feed port for the shift to
second gear.
2-3 Shift Valve
The 2-3 shift valve (Fig. 19) controls 2-3 upshifts
and downshifts. The valve is actuated by the No. 1
valve body solenoid and by line pressure from the
manual valve and primary regulator valve.
When the transmission control module activates so-
lenoid No. 1, line pressure at the top of the 2-3 valve
is released through the solenoid drain port. Spring
tension moves the valve up to hold the valve in sec-ond gear position. As the solenoid is deactivated, line
pressure then moves the valve down exposing the di-
rect clutch feed port for the shift to third gear.
3-4 Shift Valve
The 3-4 shift valve (Fig. 20) is operated by the No.
2 solenoid and by line pressure from the manual
valve, 2-3 valve and primary regulator valve.
Energizing the No. 2 solenoid causes line pressure
at the top of the 3-4 valve to be released through the
solenoid valve drain port. Spring tension moves the
valve up exposing the overdrive clutch accumulator
feed port to apply the clutch.
Fig. 19 2-3 Shift Valve
Fig. 20 3-4 Shift Valve
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De-energizing the solenoid causes the drain port to
close. Line pressure then moves the valve down ex-
posing the overdrive brake accumulator feed port for
the shift to fourth gear.
In the 1-2 or 3 gearshift lever positions, line pres-
sure from the 2-3 shift valve is applied to the lower
end of the 3-4 valve. This holds the valve upward,
closing off the overdrive brake feed port preventing a
shift into fourth gear.
Second Coast Modulator Valve
The second coast modulator valve (Fig. 21) momen-
tarily reduces line pressure from the 1-2 shift valve.
This cushions application of the second coast brake.
The valve is operative when the shift lever and man-
ual valve are in the 3 position.
Low Coast Modulator Valve
The low coast modulator valve (Fig. 22) momen-
tarily reduces line pressure from the 2-3 shift valve
to cushion application of the first/reverse brake. The
valve operates when the shift lever and manual valve
are in the 1-2 position.
Accumulator Control Valve
The accumulator control valve (Fig. 23) cushions
clutch and brake application by reducing back pres-
sure to the accumulators when throttle opening is
small. The valve is operated by oil pump (line) pres-
sure and by throttle pressure.
Accumulators
Four accumulators are used to cushion application
of the clutches and brakes (Fig. 24). The accumula-tors consist of spring loaded pistons which dampen
the initial surge of apply pressure to provide smooth
engagement during shifts.
Control pressure from the accumulator control
valve is continuously applied to the back pressure
side of the accumulator pistons. This pressure plus
spring tension holds the pistons down. As line pres-
sure from the shift valves enters the opposite end of
the piston bore, control pressure and spring tension
momentarily delay application of full line pressure to
cushion engagement. The accumulators are all lo-
cated in the transmission case (Fig. 24).
Fig. 21 Second Coast Modulator Valve
Fig. 22 Low Coast Modulator Valve
Fig. 23 Accumulator Control Valve
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Transmission Valve Body Solenoids
Three solenoids are used (Fig. 25). The No. 1 and 2
solenoids control shift valve operation by applying or
releasing line pressure. The signal to apply or release
pressure is provided by the transmission control
module.The No. 3 solenoid controls operation of the torque
converter clutch. The solenoid operates in response to
signals from the transmission control module.
When the No. 1 and 2 solenoids are activated, the
solenoid plunger is moved off its seat opening the
drain port to release line pressure. When either sole-
noid is deactivated, the plunger closes the drain port.
The No. 3 solenoid operates in reverse. When the
solenoid is deactivated, the solenoid plunger is moved
off its seat opening the drain port to release line
pressure. When the solenoid is activated, the plunger
closes the drain port.
Fig. 24 Accumulators
Fig. 25 Transmission Valve Body Solenoids
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