low oil pressure ISUZU TF SERIES 2004 Workshop Manual

CONSTRUCTION AND FUNCTION 7A1-27
Item Description
- 4L mode -
4L mode setting condition
4L switch: On
Vehicle speed: More than 5km/h
Above conditions are met at the same time.
4L mode reset condition
4L switch: Off
Vehicle speed: Less than 4km/h
Above conditions are met at the same time.

- Down slope mode -
Down slope mode setting condition
Brake switch: On
Engine idle condition: More than 2.5 seconds
Select lever position: D or 3 range
Vehicle speed: More than 55km/h
Vehicle speed change: More than 1km/h
Above conditions are met at the same time.
Down slope mode reset condition
Engine idle condition: Not idle condition
Select lever position: Other than D or 3 range
At least, one of above conditions is met.

- Power Mode -
When power drive switch is On at only D range or 3 range, the shift change is performed by
1 – 4 speed based on shift diagram set as power pattern.

- Up slope mode -
Up-slope reasoning value is calculated from the average throttle angle and the average
acceleration. Otherwise, up-slope reasoning value is calculated from the vehicle speed.
TCM judges as up-slope mode when the former is bigger than latter.


Lock-up control The lock-up solenoid adjusts the pressure based on the signal from the TCM according to
the vehicle speed, throttle opening and other input signals based on the pre-set lock-up
point to control the lock-up.
Smooth lock-up control engages and disengages the clutch smoothly at the time of lock-up.
When the oil temperature is low (below 20
C) or high (above 128
C), lock-up is prohibited
even when the vehicle is at a lock-up speed.
The lock-up is disengaged also when the throttle is closed.
Direct electronic shift
control (DESC)
The duty cycle type solenoid is used for each clutch and brake. The solenoid adjusts the
clutch pressure to be suited to the engine load and vehicle traveling condition based on the
signal from the TCM. The pressure switch provided in the control valve oil passage sends
the oil pressure condition to the TCM to control the disengagement and engagement of the
clutch and brake directly and finely.
Learning control Learning is controlled to correct the oil pressure control timing to engage or disengage the
clutch optimally in order to compensate changes of the engine performance and changes
of the transmission with time. It is controlled to bring the speed-change time closer to the
value pre-set to the TCM.

CONSTRUCTION AND FUNCTION 7A1-29
CONTROL ITEM, INPUT AND OUTPUT

Control item


Item

Line
pressure
control
Gear
shift
control
Shift
pattern
selection
Lock-up
controlDirect
electronic
shift
control
(DECS)
Learning
control
Fail-safe
function
Self-
diagnosis
function
Speed sensor
Turbine sensor
Engine speed sensor
Brake switch

Inhibitor switch
Mode select switch

4L switch (4WD Only)

ATF thermo sensor
High clutch oil pressure switch

2-4 brake oil pressure switch

Low & Reverse brake oil pressure
switch
Input
Throttle position sensor
Line pressure solenoid
Low clutch solenoid

High clutch solenoid

2-4 brake solenoid

Low & Reverse brake solenoid

Lock-up solenoid

Shift pattern indicator lamp

ATF temperature indicator lamp

Output
Check trans indicator lamp

7A1-30 CONSTRUCTION AND FUNCTION
LINE PRESSURE CONTROL

Either the throttle opening, vehicle speed, turbine rotational speed, ATF temperature or speed-change
range signal appropriate under the situation is issued from the TCM. The ON/OFF type line pressure
solenoid is actuated and switches the line pressure to high or low pressure.

The line pressure generated by the oil pump acts on the point A of the pressure regulator valve. When
the pressure control solenoid is turned ON by the signal from the TCM, the solenoid pressure does not
act. The line pressure is adjusted to match the spring force acting on the right side of the pressure
regulator valve.

When the pressure control solenoid is turned OFF, the solenoid pressure acts so that the line pressure is
adjusted to match the spring force acting on the right side of the pressure regulator valve.

As a result, the line pressure is adjusted to be low when the pressure control solenoid is ON and to be
high when the pressure control solenoid is OFF.

In the D, 3, 2 and L range, the line pressure through the oil pressure circuit acts onto the point B of the
pressure regulator valve and the pressure regulator valve moves so as to increase the pressure to be
drained, so that the line pressure is adjusted to be lower than the P, N, and R range by the difference of
area at the point B.




Figure 50. Line Pressure Control

LOCK-UP CONTROL

The lock-up solenoid adjusts the pressure and controls the lock-up based on the pre-set lock-up point,
according to the vehicle speed, throttle opening, engine rotations, turbine rotations and ATF temperature
input signal, based on the signal from the TCM.

Smooth lock-up control is employed to engage or disengage the clutch smoothly at the time of lock-up.

When the oil temperature is low (below 20C) or high (over 128C), lock-up is disengaged even though
the vehicle is at the lock-up speed.

The lock-up is disengaged also when the throttle is closed.

When the TCM determines the lock-up engagement, the DUTY ratio to supply power to the lock-up
solenoid is gradually increased (5% to 95%) and the oil between the lock-up piston and converter cover is
gradually drained.
As a result, the lock-up piston is fitted slowly under pressure to the converter cover securing smooth lock-
up engagement.

CONSTRUCTION AND FUNCTION 7A1-31


Figure 51. Lock-up Control

DIRECT ELECTRIC SHIFT CONTROL (DESC)
Feature

Based on the each switch signals (low & reverse brake pressure, 2-4 brake pressure & high clutch
pressure) and sensors signals (turbine sensor, speed sensor, engine speed signal & throttle position
signal), duty cycle type solenoid adjusts the clutch pressure to match the engine load and vehicle
traveling condition. By this result, controlling the engagement and disengagement of the clutch and brake
pressure is directly and accurately controlled via TCM, which is not realized in previous accumulator type.
Operation

Instead of the previous system (on/off type of shift solenoid and shift valve), the combination of duty cycle
type solenoid and amplifier (Amp) valve are used to adjust the clutch pressure to match the engine load
and vehicle traveling condition based on the signal from the TCM, and the pressure switch provided in the
oil passage of the control valve transmits the oil pressure condition at that time to TCM, thus controlling
the engagement and disengagement of the clutch and brake directly and finely.

When the gear is shifted from the 2nd to 3rd, 3rd to 4th (O/D), 4th (O/D) to 3rd and 3rd to 2nd, the clutch
pressure on the engagement side and that on the disengagement side are simultaneously controlled.
As a result, engine racing or clutch drag is prevented securing smooth and quick speed change response

7A1-34 CONSTRUCTION AND FUNCTION
MAJOR INPUT/OUTPUT COMPONENT AND THEIR FUNCTIONS
Speed sensor Detects output shaft revolution and sends rpm signal to TCM.
Turbine sensor Detects input shaft revolution and sends rpm signal to TCM.
Engine speed sensor Inputs engine revolution from engine control computer.
Brake switch Detects brake pedal operated by the driver and sends signal to
TCM.
Inhibitor switch Detects select lever position and sends signal to TCM.
Mode select switch Detects "Power Drive" or "3rd Start" selected by the driver and
sends signal to TCM.
4L switch (4WD Only) Inputs 4L mode from transfer control computer.
ATF thermo sensor Detects ATF temperature and sends signal to TCM.
High clutch oil pressure switch Detects high clutch supply oil pressure and sends signal to
TCM.
2-4 brake oil pressure switch Detects 2-4 brake supply oil pressure and sends signal to
TCM.
Low & Reverse brake oil pressure switch Detects low & reverse brake supply oil pressure and signal to
TCM.
Throttle position sensor Inputs throttle opening angle from engine control computer.
Input
TCM Judges necessary line pressure, gear shifting point and lock-up
operation based on electrical signals from switches and
sensors and sends appropriate signals to solenoids.
Line pressure solenoid Regulates oil pump delivery pressure to the appropriate line
pressure for current driving condition based on signal from
TCM.
Low clutch solenoid Selects appropriate gear shifting position for current driving
condition and regulates low clutch supply oil pressure based on
signal from TCM.
High clutch solenoid Selects appropriate gear shifting position for current driving
condition and regulates high clutch supply oil pressure based
on signal from TCM.
2-4 brake solenoid Selects appropriate gear shifting position for current driving
condition and regulates 2-4 brake supply oil pressure based on
signal from TCM.
Low & Reverse brake solenoid Selects appropriate gear shifting position for current driving
condition and regulates low & reverse brake supply oil
pressure based on signal from TCM.
Lock-up solenoid Regulates lock-up pressure to appropriate level for current
driving conditions based on signal from TCM.
Mode indicator lamp Indicates POWER DRIVE or 3rd START switch position.
Speed meter signal (2WD Only) Outputs vehicle speed to speed meter.
A/T OIL TEMP indicator lamp Indicates A/T OIL TEMP indicator lamp in case of high
temperature.
Output
CHECK TRANS indicator lamp Indicates CHECK TRANS indicator lamp in case of
malfunction.

CONSTRUCTION AND FUNCTION 7A1-35
CONTROL CIRCUIT BLOCK DIAGRAM



Speed sensor
Turbine sensor
Brake switch
Inhibitor switch
Power drive, 3rd start
switch
ATF oil thermo sensor
High clutch oil pressure
switch
2-4 brake oil pressure
switch
Low & reverse brake oil
pressure switch
Transfer control module
(4WD Only)



Engine Control Module
(ECM)
Line pressure solenoid
Low clutch solenoid
High clutch solenoid
2-4 brake solenoid
Low & reverse brake
solenoid
Lock-up solenoid
ATF temperature
indicator lamp
Speed meter (2WD
Only)
Power, 3rd start indicator
lamp
Check trans indicator
lamp
Data link connector Self-diagnosis
function



Transmission
Control
Module
(TCM)
4L mode
Engine
speed
Throttle
angle
Figure 54. Control Circuit Block Diagram

7A1-36 CONSTRUCTION AND FUNCTION
GEAR TRAIN (TRANSMISSION MECHANISM) OPERATION AND
HYDRAULIC CIRCUIT
CONSTRUCTION AND OPERATION
The JR405E consists of two sets of planetary gears, three multiple plate clutches, two multiple plate brakes
and one one-way clutch.





COMPONENT NAME AND FUNCTION
Component Name Symbol Function
Low Clutch L/C Connects the front planetary carrier to the rear
internal gear.
Engaged at 1st, 2nd and 3rd gear.
High Clutch H/C Connects the input shaft to the front planetary
carrier.
Engaged at 3rd and 4th (O/D) gear.
Reverse Clutch R/C Connects the input shaft to the front sun gear.
Engaged at Reverse gear.
Low & Reverse Brake L&R/B Locks the front planetary carrier.
Engaged at L range and Reverse gear.
2-4 Brake 2-4/B Locks the front sun gear.
Engaged at 2nd and 4th (O/D) gear.
Low One-way Clutch L/O.C Allows the front planetary carrier to turn forward
(clockwise) but locks to opposite direction
(counterclockwise).
Operative when accelerating.
Low Clutch Solenoid L/C.S Regulates low clutch pressure.
High Clutch Solenoid H/C.S Regulates high clutch pressure.
Low & Reverse Brake Solenoid L&R/B.S Regulates low & reverse brake pressure.
2-4 Brake Solenoid 2-4/B.S Regulates 2-4 brake pressure.
Lock-up Solenoid L/U.S Regulates lock-up clutch pressure.
High Clutch Oil Pressure SW H/C.P/SW Detects high clutch supply oil pressure.
Low & Reverse Brake Oil Pressure SW L&R/B.P/SWDetects low & reverse brake supply oil pressure.
2-4 Brake Oil Pressure SW 2-4/B.P/SWDetects 2-4 brake supply oil pressure.

DIAGNOSIS (JR405E) 7A2-5
PAGE
NO. Z3: MODE LAMP (POWER DRIVE OR 3RD START) LIGHTS UP WHEN
THE POWER MODE OR 3RD START MODE IS TURNED OFF .................................. 7A2-137
NO. Z4: OIL TEMPERATURE WARNING LAMP LIGHTS UP ...................................... 7A2-137
NO. Z5: SELECT LEVER FEELING IS FAULTY. .......................................................... 7A2-137
NO. Z6: POOR FUEL CONSUMPTION ......................................................................... 7A2-138
NO. Z7: PATTERN SELECT SWITCH IS FAULTY........................................................ 7A2-138
NO. Z8: OIL IS SPLASHED DURING THE RUNNING .................................................. 7A2-138
NO. Z9: ABNORMAL SMELL ........................................................................................ 7A2-138
NO. Z10: ATF QUANTITY IS LOW OR HIGH ................................................................ 7A2-138
NO. Z11: ABNORMAL OIL PRESSURE........................................................................ 7A2-139
NO. Z12: REVERSE BUZZER DOES NOT RING .......................................................... 7A2-139
STALL TEST .................................................................................................................. 7A2-140
LINE PRESSURE TEST................................................................................................. 7A2-141
TIME LAG TEST............................................................................................................. 7A2-143
TEST DRIVE................................................................................................................... 7A2-144
SHIFT POINT CHART .................................................................................................... 7A2-147
SHIFT POINT DIAGRAM................................................................................................ 7A2-149
TCM VOLTAGE CHECK ................................................................................................ 7A2-154

7A2-12 DIAGNOSIS (JR405E)
F0: Diagnostic Trouble Code
F0: Read DTC Infor As Stored By ECU
F1: Clear DTC Information
F1: Data Display
F2: Snapshot
F3: Miscellaneous Test
F0: Lamp
F0: Power Lamp Test
F1: 3rd Start Lamp Test
F2: AT Oil Temperature Lamp Test
F3: Transmission Check Light Test
F1: Solenoids
F0: Low & Reverse Brake Solenoid
F1: 2-4 Brake Solenoid
F2: High Clutch Solenoid
F3: Low Clutch Solenoid
F4: Line Pressure Solenoid
F5: Lock Up Duty Solenoid
F4: Programming
F0: Program VIN
F1: Lock ECU

F0: Diagnostic Trouble Code
The purpose of the "Diagnostic Trouble Codes" mode is to
display stored trouble code in the TCM.
When "Clear DTC Information" is selected, a "Clear DTC
Information", warning screen appears. This screen informs you
that by cleaning DTC's "all stored DTC information in the TCM
will be erased".
After clearing codes, confirm system operation by test driving
the vehicle.

F1: Data Display
The purpose of the "Data Display" mode is to continuously
monitor data parameters.
The current actual values of all important sensors and signals
in the system are display through F1mode.
See the "Typical Scan Data" section.

F2: Snapshot
"Snapshot" allows you to focus on making the condition occur,
rather than trying to view all of the data in anticipation of the
fault. The snapshot will collect parameter information around a
trigger point that you select.

F3: Miscellaneous Test:
The purpose of "Miscellaneous Test" mode is to check for
correct operation of electronic system actuators.

F4: Programming (Factory Use Only):
The purpose of "Programming" is to program VIN in the ECM
and lock the programmed data.

7A2-14 DIAGNOSIS (JR405E)
MISCELLANEOUS TEST
The state of each circuit can be tested by using miscellaneous test menus. Especially when DTC cannot be
detected, a faulty circuit can be diagnosed by testing each circuit by means of these menus.
Even DTC has been detected, the circuit tests using these menus could help discriminate between a mechanical
trouble and an electrical trouble.

Connect Tech 2 and select "Powertrain", "JR 405E" & "Miscellaneous Test".
F0: Lamps
The circuit is normal if the warning light in the meter panel comes on and goes out in accordance with Tech 2
instruction.

Lamps

F0: Power Lamp Test
F1: 3rd Start Lamp Test
F2: AT Oil Tempeature Lamp Test
F3: Transmission Check Light Test


F0: Power Lamp Test


Power Lamp Test

Power Lamp Off



 Press "Active" key.
Then, "POWER DRIVE" indicator lamp is turned on in the meter panel.
 Press "Inactive" key.
Then, "POWER DRIVE" indicator lamp is turned off in the
meter panel.
 Press "Quit" Key to cancel the test.
F1: 3rd Start Lamp Test
F2: AT Oil Temperature Lamp Test
F3: Transmisstion Check Light Test
Test procedure is same as "F0: Power Lamp Test".
The circuit is normal if the warning light in the meter panel
comes on and goes out in accordance with Tech 2 instruction.

F1: Solenoids
The circuit is normal if clicking sound is generated in accordance with Tech 2 instruction.

Solenoids
F0: Low & Reverse Brake Solenoid
F1: 2-4 Brake Solenoid
F2: High Clutch Solenoid
F3: Low Clutch Solenoid
F4: Line Pressure Solenoid
F5: Lock Up Duty Solenoid