2004 ISUZU TF SERIES low oil pressure

7A4–66 UNIT REPAIR (AW30–40LE)
5. Place special tool on the spring retainer and
compress the return spring.
Using snap ring pliers, remove the snap ring.
Spring compressor : J–25048
24 8RY 0 000 3
6. Remove the piston return spring.
7. Place the forward clutch drum onto the OD support.
Holding the forward clutch piston by hand, apply
compressed air to the OD support to remove the
forward clutch piston.
24 8RY 0 004 2
8. Remove the O-rings from piston.
9. Remove the O-ring from forward clutch drum.
10. Remove the oil seal rings and thrust bearing from
forward clutch drum.
Inspection and Repair
1. Check forward clutch piston
Check that check ball is free by shaking the piston.
Check that the valve does not leak by applying
low-pressure compressed air.
24 8RY 0 0031
2. Check forward clutch drum bushing.
Using a dial indicator, measure the inside diameter
of the forward clutch drum bushing.
Maximum inside diameter: 24.08 mm (0.948 in)
If the inside diameter is greater then the maximum,
replace the forward clutch drum.
24 8RY 0 0043
3. Check disc, plate and flange.
Check to see if the sliding surface of the disc, plate
and flange are worn or burnt. If necessary, replace
them.
If the lining of the disc is peeling off or discolored,
or even if parts of the printed numbers are
defaced, replace all discs.

CONSTRUCTION AND FUNCTION 7A1-3

DESCRIPTION
CONSTRUCTION



































1 Converter Housing 6 Low Clutch 11 Oil Pump
2 Torque Converter 7 Low & Reverse Brake 12 Control Valve
3 High Clutch 8 Output Shaft 13 Low One-way Clutch
4 Reverse Clutch 9 Extension Housing 14 Parking Gear
5 2-4 Brake 10 Input Shaft

Figure 1. Construction of Automatic Transmission

The JR405E automatic transmission is electrically controlled by a microcomputer transmission control module
(TCM). There are four forward speeds and one reverse speed.
This JR405E automatic transmission employs a clutch pressure direct control system (Direct Electronic Shift
Control: DESC) using a duty cycle type solenoid, which ensures high shift quality.
This transmission also controls learning and constantly checks the time of each clutch and brake required for
the speed change to match this time with the target value for the optimum speed change.

The TCM will automatically select the most appropriate shift points and lock-up points depending on the
throttle opening angle, the vehicle speed and the vehicle load.
If any trouble arises in the vehicle sensor, throttle sensor, solenoid, etc., the fail-safe control function is
activated to keep the running performance.
Problems with the sensors, the solenoids can be quickly detected with the self diagnosis procedure described
in this manual.

The JR405E automatic transmission consists of the torque converter, the oil pump, the input shaft, the out put
shaft, the planetary gears and the control valve.
The gear train consists of two planetary gear sets and three multiple plate clutches in combination with two
multiple plate brakes and a one-way clutch.
2WD
4WD

7A1-6 CONSTRUCTION AND FUNCTION
ELECTRONIC CONTROL COMPONENTS LOCATION

4WD Only 4WD Only
Instrument panel (Meter)







Speed meter (2WD Only)
Shift position indicator lamp
POWER DRIVE, 3rd START
indicator lamp
A/T OIL TEMP indicator lamp
CHECK TRANS indicator lam
p

Brake pedal





Brake Switch
Select lever








Power Drive
, 3rd Start select switch
Transmission Control Module (TCM)
Electrical source






Ignition
Battery voltage
Speed sensor
Turbine sensor
Inhibitor switch
ATF thermo sensor
High clutch oil pressure switch
2-4 brake oil pressure switch
Low & Reverse brake oil pressure
switch
Line pressure solenoid
Low clutch solenoid
High clutch solenoid
2-4 brake solenoid
Low & Reverse brake solenoid
Lock-up solenoid
Transmission
Transfer Control Module
Transfer




4L mode switch
Engine




Engine speed sensor
Throttle Position Sensor


Engine Control Module (ECM)
Data link connector

7A1-8 CONSTRUCTION AND FUNCTION
STRUCTURE AND FUNCTION OF COMPONENT
TORQUE CONVERTER (WITH LOCK-UP FUNCTION)

The torque converter is a device for transmitting the engine torque to the transmission. It transmits power
by means of oil when the lock-up is disengaged and by means of a lock-up piston when it is engaged.

The torque converter is of the symmetrical, three-element, single-stage, two-phase type.

As shown in the drawing, the symmetrical three-elements refer to three elements (components) consisting
of impeller (1), turbine (2) and stator (3) that are arranged symmetrically (figure 5).

"Single-stage" means that there is only one turbine as an output element; "two-phase" means that the
pump impeller acts as a torque converter when the turbine speed is comparatively low, and as a fluid
coupling when the speed is high.


















1. Pump Impeller
2. Turbine Runner
3. Stator














1. Pump Impeller
2. Turbine Runner
3. Stator
4. Converter Cover
5. One-way Clutch
6. Lock-up Piston
7. Torsion Damper

Figure 5. Torque Converter
Figure 6. Construction of Torque Converter

Lock-up mechanism

"Lock-up" refers to a fixed state of the lock-up piston inside the torque converter and thus connects the
engine directly to the transmission.

The hydraulic pressure for the lock-up control is supplied from two circuits.

When the lock-up is disengaged (Figure 7)

When the lock-up is disengaged, the torque converter operating pressure is supplied from the oil passage
(A) to between the cover and the lock-up piston, and separates the lock-up piston clutch facing and
converter cover.

As a result, the engine drive power is transmitted from the converter cover to the pump impeller, the ATF
and to the turbine. The torque converter function as a fluid connector in this condition.

The torque converter operating pressure is supplied from the oil passage (A), passes through the oil
passage (B).

When the lock-up is engaged (Figure 8)

When the lock-up is engaged, the torque converter operating pressure is supplied from oil passage (B) to
the oil pump impeller, turbine, then to the stator side. The oil between the lock-up piston and converter
cover is drained.

Since the force acting on the right side of the lock-up piston is greater than force on the left side, it
connects the lock-up piston clutch facing with the converter cover, thereby increasing the transmission
efficiency.

CONSTRUCTION AND FUNCTION 7A1-9


Figure 7. Lock-up Control (Disengaged) Figure 8. Lock-up Control (Engaged)
OIL PUMP

The oil pump generating oil pressure is a small-size trochoid gear type oil pump. It feeds oil to the torque
converter, lubricates the power train mechanism, and feeds the oil pressure to the oil pressure control unit
under pressure.

The oil pump is located behind the torque converter. Sine the inner rotor in the oil pump is fitted with the
drive sleeve of the torque converter, it works by the power from the engine.

Figure 9. Construction of Oil Pump Figure 10. Location of Oil Pump

When the inner rotor in the oil pump rotates, ATF is sucked in from the oil pan, passed between the inner
rotor, outer rotor and crescent and discharged. This pressure discharged is sent to the pressure
regulator valve in the control valve and adjusted as required for operating the A/T. The flow rate under
pressure increases or decreases in proportion of the number of rotations.


Figure 11. Operation of Oil Pump

CONSTRUCTION AND FUNCTION 7A1-11


The JR405E consists of two sets of planetary gears, which are called front planetary gear and rear
planetary gear.

The sun gear of front planetary gear is fixed to the drive plates of 2-4 brake and reverse clutch.

The planetary carrier of front planetary gear is fixed to the drum of low clutch, the drive plates of low &
reverse brake and the hub of high clutch.

The internal gear of front planetary gear and the planetary carrier of rear planetary gear are connected as
one, and they are fixed to output shaft.

The sun gear of rear planetary gear is fixed to input shaft.

The internal gear of rear planetary gear is fixed to the hub of low clutch.

Clutch and Brake

Basic structure of the clutch and brake is shown in the figures below.

In the figure A, the clutch plates (drive plate and driven plate) are in the fluid so that they slip against each
other transmitting no power.

Figure B shows the condition where the oil pressure is acting on the piston. The clutch plates are fitted
to each other under pressure transmitting the rotations of the clutch drum to the clutch hub.

When the oil pressure is removed from the piston, the clutch returns to the condition in the figure A by the
return spring.


Figure 13. Basic Construction of Clutch and Brake

Low Clutch, High Clutch and Reverse Clutch (Multi-Plate Clutch)

The multi-plate clutch is composed of drive plates and driven plates. By applying the oil pressure onto
the end surface of the plates, the clutch is engaged or disengaged. The oil pressure is adjusted with the
control valve according to the signal from the TCM.

All clutches use dish plates to prevent uncontrolled operation of the clutches when engaged, causing a
shock.

For the reverse clutch, a piston check ball is used to release the oil pressure for the purpose of preventing
the clutch drag due to oil pressure generated by residual ATF because of the centrifugal force while the
clutch is racing (under no oil pressure).

For the low clutch and high clutch, a centrifugal balance chamber always full of ATF is provided to offset
the excessive oil pressure, for the purpose of preventing the clutch drag due to oil pressure generated by
residual ATF because of the centrifugal force while the clutch is racing (under no oil pressure).

The solenoid in the control valve is driven based on the speed change signal from TCM and moves the
shift valve, thereby engaging the drive plate and driven plate through the piston of each clutch.

Resultantly, elements of the planetary gear unit are combined.

When the oil pressure is removed, the piston returns to the original position by the force of the return
spring.

CONSTRUCTION AND FUNCTION 7A1-13

2-4 Brake and Low & Reverse Brake (Multi-Plate Brake)

The multi-plate brake is composed of drive plates and driven plates. By applying the oil pressure onto
the end surface of the plates, the clutch is engaged or disengaged. The oil pressure is adjusted with the
control valve according to the signal from the TCM.

All brakes use dish plates to prevent uncontrolled operation of the clutches when engaged, causing a
shock.

The solenoid in the control valve is driven based on the speed change signal from TCM and moves the
shift valve, thereby engaging the drive plate and driven plate through the piston of each clutch.

Resultantly, rotation of each element of the planetary gear unit is fixed.

When the oil pressure is removed, the piston returns to the original position by the force of the return
spring.




Figure 19. Construction of 2-4 Brake
Figure 20. Construction of Low & Reverse Brake

Low One-way Clutch

The low one-way clutch employs the sprag which locks the counterclockwise rotation of the front planetary
carrier and rear internal gear.

The one-way clutch outer race is fitted with the low clutch drum and the inner race with the transmission
case.

The outer race rotates freely clockwise but, when it attempts to rotate counterclockwise, the sprag
functions to lock the outer race.

When the vehicle is traveling in 1st gear in the D, 3 or 2range, the low one-way clutch locks the rear
internal gear via the low clutch. It is left free in the 2nd, 3rd or 4th gear position.


Figure 21. Construction of Low One-way Clutch

7A1-14 CONSTRUCTION AND FUNCTION
CONTROL VALVE

Employing the direct electronic control (Direct Electronic Shift Control: DESC) for the clutch pressure has
simplified the oil pressure circuit, reduced the number of functional components and made the control
valve compact.

The control valve body is divided into the upper body and lower body. All solenoids, oil pressure switch
and ATF thermo sensor are installed to the lower body.

Three-way valve type solenoids providing high responsibility are employed. Some of the solenoids are
switched between ON and OFF and others repeat ON and OFF at 50Hz (duty cycle system).
Functionally, some supply output pressure when power is not supplied and others drain the output
pressure.

When the solenoid is driven based on the signal from the TCM, the oil pressure is changed. The valve is
operated by the difference of the oil pressure.


Figure 22. Construction of Valve Body