2004 ISUZU TF SERIES ECU

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

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.

DIAGNOSIS (JR405E) 7A2-17
SNAPSHOT DISPLAY WITH TIS2000 (For Snapshot Data Analysis)
Procedures for transferring and displaying Tech2 snapshot data by using TIS2000 [Snapshot Upload] function is
described below.
Snapshot data can be displayed with [Snapshot Upload] function included in TIS2000.
By analyzing these data in various methods, trouble conditions can be checked.
Snapshot data is displayed by executing the three steps below shown:


1. Record the snapshot data, in Tech2.
2. Transfer the snapshot data to PC.
After recording the snapshot in Tech2, transfer the data from Tech2 to PC by the below procedures.
1. Start TIS2000.
2. Select [Snapshot Upload] on the TIS2000 start screen.
3. Select [Upload from trouble diagnosis tool (transfer from diagnosis tester)] or click the corresponding icon of
the tool bar.
4. Select Tech2, and transfer the recorded snapshot information.
5. Select the transferred snapshot.
6. After ending transfer of the snapshot, data parameter list is displayed on the screen.

DIAGNOSIS (JR405E) 7A2-23


4. After choosing the data, click the "Next" button.
5. When all the necessary information is entered, the "details" of software within the database that match the
entered data will appear for confirmation. Click the "Program" switch and then download the new software
onto Tech-2.
6. "Data Transfer" comes on display. The progress of downloading will be displayed on the screen in the form of
bar graph.
7. Upon finishing the data transfer, turn off the power of Tech-2, removing from P/C.


4. Programming of TCM
1. Check to see if batteries are fully charged, while ABS connectors shall be removed from the vehicle.
2. Connect Tech-2 to Vehicle Diagnostic Connectors.
3. Turn on the power of Tech-2 and the title screen comes on display.
4. Turn on the ignition (without allowing the engine to start)
5. On the title screen of Tech-2, push the "Enter" button.
6. Choose "F1: Service Programming System" on the main screen and then choose "F1: Programming ECU".
7. While data is being transferred, "Programming in Progress" will be displayed on the Tech-2 screen.
8. Upon finishing the data transfer, Tech-2 will display "Reprogramming was Successful". Push the "Exit" button
to bring program to completion.
9. Following "Procedure 2: Demand of Data", try over again "Information Obtaining" and check to confirm if the
data has been correctly re-loaded.
10. Upon finishing confirmation, turn off the ignition of the vehicle and then turn off the power of Tech-2,
removing from the vehicle.

7A2-34 DIAGNOSIS (JR405E)


Flash Code
(P-Code)

CHECK TRANS Flash Pattern

Description
CHECK
TRANS
Warning

34 (P0768) Low Clutch Duty Solenoid FailureON


35 (P0748) Line Pressure Solenoid Failure ON


36 (P1860) Lock-up Duty Solenoid Failure ON


41 (P0731) 1stGearRatioError ON


42 (P0732) 2ndGearRatioError ON


43 (P0733) 3rdGearRatioError ON


44 (P0734) 4thGearRatioError ON


51 (P1750) ON

Low & Reverse Brake Fail-safe
Valve Failure

52 (P1755) 2-4BrakeFail-safeValveFailure ON


- (P0602) No Flash Code ECU Programming Error ON

DIAGNOSIS (JR405E) 7A2-35
FAIL-SAFEFUNCTION
Fail-Safe Condition
Flash Code
(P-Code)

Description
CHECK
TRANS
Warning

Gear Shift
Solenoid
Line
Pressure
Solenoid

Lock-up

Remark
11
(P0722)
Vehicle peed Sensor No
Signal ON 3rdFix All Stop - Inhibited
13
(P0727)
Engine Revolution Sensor
No Signal ON - - - Inhibited
14
(P0717)
Turbine Speed Sensor No
Signal ON 3rdFix All Stop - Inhibited
15
(P0710)
ATF Temperature Sensor
Failure OFF 3,2,L - - Inhibited*1
16
(P0560)
System Voltage Failure ON 3rdFix All Stop - Inhibited*2
17
(P0705)
Inhibitor Switch Failure ON 3rdFix All Stop - Inhibited
22
(P1120)
Throttle Signal Failure ON 3rdFix All Stop - Inhibited
25
(P1875)
GND Return Circuit
Failure ON 3rdFix All Stop - Inhibited*2
26
(P1853)
Low & Reverse Brake
Pressure Switch Failure ON No Fail-safe Function
27
(P1858)
2-4 Brake Pressure
Switch Failure ON No Fail-safe Function
28
(P1863)
High Clutch Pressure
Switch Failure ON No Fail-safe Function
31
(P0753)
Low & Reverse Brake
Duty Solenoid Failure ON 3rdFix All Stop - Inhibited
32
(P0758)
2-4 Brake Duty Solenoid
Failure ON 3rdFix All Stop - Inhibited
33
(P0763)
High Clutch Duty Solenoid
Failure ON 3rdFix All Stop - Inhibited
34
(P0768)
Low Clutch Duty Solenoid
Failure ON 3rdFix All Stop - Inhibited
35
(P0748)
Line Pressure Solenoid
Failure ON - - Stop -
36
(P1860)
Lock-up Duty Solenoid
Failure ON - - - Inhibited
41
(P0731)
1stGearRatioError ON No Fail-safe Function
42
(P0732)
2ndGearRatioError ON No Fail-safe Function
43
(P0733)
3rdGearRatioError ON No Fail-safe Function
44
(P0734)
4thGearRatioError ON No Fail-safe Function
51
(P1750)
Low & Reverse Brake
Fail-safe Valve Failure ON 3rdFix All Stop - Inhibited
52
(P1755)
2-4 Brake Fail-safe Valve
Failure ON 3rdFix All Stop - Inhibited
-
(P0602)
ECU Programming Error ON No Fail-safe Function
*1: When the engine speed is more than 470 rpm for 10 minuets, the lock-up and gear shift to 4th (over-drive) are
allowed.
*2: In case of fail-safe valve failure, gear shift to 4th (over-drive) is inhibited.

7A3-4 ON-VEHICLE SERVICE (JR405E)
TRANSMISSION CONTROL MODULE (TCM)



RTW37ALF001901

Remove and Disconnect
1. Disconnect the negative battery cable.
2. Remove the connectors.
3. Remove the fixing nuts and remove the TCM (1)
from the bracket.
Note:
The TCM is fitted under instrument panel of the driver’s
compartment by means of three stud bolts.


Install or Connect
Follow the removal steps in the reverse order. Be
absolutely sure that the connectors are securely
fastened.
AT CONT