ISUZU KB P190 2007 Workshop Repair Manual

7A1-22 CONSTRUCTION AND FUNCTION
TURBINE SENSOR
• The turbine sensor is a hall element. It is installed to the front of the transmission case. The turbine
sensor converts the rotations of the reverse & high clutch drum fitted with the input shaft by spline to
pulse signal and sends the signal to the TCM.
• One turn of the reverse & high clutch drum generates 32-pulse signals, which are sent to the TCM.


Figure 38. Turbine Sensor

SPEED SENSOR
• The speed sensor is a hall element. It is installed to the rear of the transmission case. The speed sensor
converts the rotations of the parking gear, fitted with the output shaft by spline, to a pulse signal and
sends the signal to the TCM.
• One turn of the parking gear generates 16-pulse signals, which are sent to the TCM.


Figure 39. Speed Sensor Figure 40. Location of Turbine & Speed Sensor



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ISUZU KB P190 2007

CONSTRUCTION AND FUNCTION 7A1-23
ACCELERATOR PEDAL POSITION SENSOR
• Opening of the accelerator pedal is converted to an electric signal which is transmitted from ECM to TCM.
• The accelerator pedal position sensor (1) is installed to the accelerator pedal.





Pin
No. W ire Color
Pin Function
1 BLU APP Sensor 3 +5V Reference
2 Not Used
3 ORN/BLU APP Sensor 2 Low Reference
4 BLK APP Sensor 1 Low Reference
5 RED APP Sensor 1 Signal
6 BLU/W HT APP Sensor 3 Signal
7 BLU/RED APP Sensor 3 Low Reference
8 ORN APP Sensor 2 +5V Reference
9 BLU/GRN APP Sensor 2 Signal
10 W HT APP Sensor 1 +5V Reference
RTW 77ASH000501
Figure 41. Accelerator Pedal Position Sensor
Figure 42. Pin Assignment

ENGINE SPEED SENSOR (=CKP SENSOR)
• The engine speed sensor converts the crankshaft from the Crankshaft Position (CKP) sensor rotation to a
pulse signal which is transmitted from ECM to TCM.








Pin
No. W ire Color
Pin Function
1 YEL Sensor Signal
2 BLU Sensor Low Reference
3 GRN Sensor +5V Feed
Figure 43. Crankshaft Position (CKP) Sensor Figure 44. Pin Assignment



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7A1-24 CONSTRUCTION AND FUNCTION
BRAKE SWITCH
• The brake switch (1) is installed to the brake pedal (2). When the driver steps on the brake pedal, an
electric signal is sent to the TCM.







TCM A3 +12V
RTW 77ASH000601
Figure 45. Brake Switch
Figure 46. Pin Assignment


MODE SELECT SWITCH
• The mode select switch (2) is installed beside the select lever (1). When the driver selects the PWR or
3rd, an electric signal is sent. It turns ON the indicator lamp in the meter.
• The 3rd START mode can only be used in the D position.












Power 3rd Illumination
Lamp
1 (Illumination)
2 (Ground)
3 (TCM A24)
4 (No Connection)
5 (TCM A11)
6 (Ground)

21
65 4 3
RTW 77ASH000701
Figure 47. Mode Select Switch
Figure 48. Pin Assignment



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CONSTRUCTION AND FUNCTION 7A1-25
TRANSMISSION CONTROL MODULE (TCM)
• The TCM is fitted on the side of the brake pedal via two stud bolts.
• The TCM judges the line pressure, gear shifting point and lock-up operation based on electrical signals
from switches and sensors, and sends the appropriate signals to solenoids.





B9 B8 B7 B6 B5 B4 B3 B2 B1 A9 A8 A7 A6 A5 A4 A3 A2 A1
B18 B17 B16 B15 B14 B13 B12 B11 B10 A18 A17 A16 A15 A14 A13 A12 A11 A10
B24 B23 B22 B21 B20 B19 A24 A23 A22 A21 A20 A19
Connect to White Connector Connect to Grey Connector


Figure 49. Pin Assignment

Pin No. Pin Assignment Pin No.Pin Assignment
B1 2-4 Brake Oil Pressure Switch A1 V BATT (Battery Back-up Power Supply)
B2 2 Position Switch A2 P Position Switch
B3 Turbine Sensor A3 Brake Switch
B4 ATF Thermo Sensor A4 3rd Start Indicator Lamp
B5 Ground A5 K-Line Signal (Tech 2 Serial Communication)
B6 Low & Reverse Brake Duty Solenoid A6 No Connection
B7 2-4 Brake Duty Solenoid A7 Engine Speed Sensor
B8 High Clutch Duty Solenoid A8 No Connection
B9 Low Clutch Duty Solenoid A9 No Connection
B10 N Position Switch A10 Vehicle Speed Sensor Out (2W D Only)
B11 D Position Switch A11 3rd START Select Switch
B12 Low & Reverse Brake Oil Pressure Switch A12 4L Mode Switch (4W D Only)
B13 Vehicle Speed Sensor A13 No Connection
B14 ATF Thermo Sensor Ground A14 No Connection
B15 No Connection A15 No Connection
B16 No Connection A16 Accelerator Pedal Position Sensor
B17 Lock-up Duty Solenoid A17 3 Position Switch
B18 Vign (Ignition Power Supply) A18 DIAG Switch (Test Switch)
B19 R Position Switch A19 A/T OIL TEMP Indicator Lamp
B20 High Clutch Oil Pressure Switch A20 CHECK TRANS Indicator Lamp
B21 L Position Switch A21 POW ER DRIVE Indicator Lamp
B22 Ground (Shift Solenoid) A22 No Connection
B23 Line Pressure Solenoid A23 No Connection
B24 Vign (Ignition Power Supply) A24 POW ER DRIVE Select Switch

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7A1-26 CONSTRUCTION AND FUNCTION
CONTROL MECHANISM
CONTENT OF FUNCTION AND CONTROL
Item Description
Line pressure control TCM issues a signal according to vehicle travel, engine load and other conditions, which
drives the ON/OFF type line pressure solenoid to switch the line pressure to high or low
pressure.
The line pressure solenoid is switched to the low pressure side when the solenoid is turned
ON (power supplied) and to the high pressure side when turned OFF (no power supplied).
In the forward travel position (D, 3, 2, L position), the line pressure decreases lower than
that in the P, N, and R position through the oil pressure circuit.


Gear shift control The TCM issues a shift solenoid drive signal based on the traveling mode switch, inhibitor
switch, the vehicle speed, the APP opening and other input signals, to control the optimum
gear position automatically.
Shift features have been set up to the TCM; the normal mode is suited to normal travel, and
the power mode is used when the vehicle is loaded or the speed accelerated.
In addition, shift features used only for high oil temperature, hill climbing, and downward
travel have been set up to the TCM. These are automatically switched depending on the
travel conditions.
W hen the oil temperature is low (10°C or less), shifting up from the third speed to the fourth
speed is prohibited by the gear shift control.


Shift pattern selection
control
The TCM selects the following shift pattern according to a vehicle condition.

Selection
Priority Shift Pattern 3rd Start
Lamp Power Drive
Lamp
High High Temperature OFF OFF
3rd Start ON
4L
Power SW Off
OFF
Down Slope
Power SW On
Power ON

Up Slope
Low Normal



OFF
OFF
- High temperature mode -
High temperature mode setting condition
ATF temperature: 122 °C or more
Above condition is met for 10.16 seconds.
High temperature mode cancel condition
ATF temperature: 115 °C or less
Above condition is met for 10.16 seconds.

-NOTE-
High temperature mode may be activated with driving conditions other than the setting
conditions stated, in order to protect Automatic Transmission from thermal damage.

- 3rd start mode -
3rd start mode setting condition
3rd start switch: On → Off (Pushed)
Vehicle speed: 11km/h or less.
ATF temperature: 115 °C or less.
APP position: 8% or less.
Select lever position: D position
Above conditions are all met at the same time.




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CONSTRUCTION AND FUNCTION 7A1-27
Item Description
3rd start mode reset condition
3rd start switch: On → Off again(Pushed again)
Vehicle speed: 34km/h or more
Select lever position: Other than D position
At least, one of above conditions is met.

- 4L mode -
4L mode setting condition
4L switch: On
Vehicle speed: 5km/h or more
Above conditions are all met at the same time.
4L mode reset condition
4L switch: Off
Vehicle speed: Less than 5km/h
Above conditions are all met at the same time.

- Down slope mode -
Down slope mode setting condition
Brake switch: On
Accelerator pedal condition: Released for 2 seconds or more.
Select lever position: D or 3 position
Vehicle speed: More than 60km/h
Increment of vehicle speed: More than 1km/h per second
Above conditions are all met at the same time.
Down slope mode reset condition
Accelerator pedal condition: Depressed
Select lever position: Other than D or 3 position
At least, one of above conditions is met.

- Power Mode -
W hen the power drive switch is On the shift pattern 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 APP angle and the average
acceleration. Otherwise, up-slope reasoning value is calculated from the vehicle speed.
TCM chooses up-slope mode when the former is bigger than the latter.


Lock-up control The lock-up solenoid adjusts the pressure to control the lock-up according to the signal
from the TCM. This signal is based on the vehicle speed, APP opening and other input
signals based on the pre-set lock-up point.
Smooth lock-up control engages and disengages the clutch smoothly at the time of lock-up.
W hen the oil temperature is low (20°C or less), lock-up is prohibited even when the vehicle
is at a lock-up speed.
The lock-up is also disengaged when the APP 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 suit 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, which controls the disengagement or engagement of the
clutch and brake directly and finely.

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7A1-28 CONSTRUCTION AND FUNCTION
Item Description
Learning function The learning function is provided 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 shift time closer to
the value pre-set to the TCM.
Fail-safe function In the case of a malfunction of the vehicle speed sensor, APP sensor, all solenoids or the
inhibitor switch, TCM automatically begins fail-safe control to minimize effects on driving.
The gear is fixed in 3rd gear and the power supply to the solenoid is shut off so that the
solenoid does not work. Lock up clutch is disengaged in this mode.
Self-diagnosis function Parts required for controlling the automatic transmission are provided with a self-diagnosis
function. W hen any trouble occurs, the check trans indicator lamp blinks to warn the driver.
The trouble code is memorized in the TCM.

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

Control item

Item

Line
pressure control
Gear shift
control
Shift
pattern
selection
Lock-up control Direct
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 (4W D Only)

ATF thermo sensor
High clutch oil pressure switch

2-4 brake oil pressure switch
Low & Reverse brake oil pressure
switch
Input
Accelerator Pedal 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



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7A1-30 CONSTRUCTION AND FUNCTION
LINE PRESSURE CONTROL
• The TCM drives the ON/OFF type line pressure solenoid based on the APP opening, vehicle speed,
turbine rotational speed, ATF temperature and shift position signal. The ON/OFF type line pressure
solenoid is actuated, and switches the line pressure to a high or low pressure number appropriate to the
situation.
• 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 position D, 3, 2 and L, the line pressure through the oil pressure circuit acts onto the point B of the
pressure regulator valve. 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 position 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, APP 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 on
or off.
• When the oil temperature is low (20°C or less), lock-up is disengaged even though the vehicle is at the
lock-up speed.
• The lock-up is disengaged also when the APP 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.

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CONSTRUCTION AND FUNCTION 7A1-31
As a result, the lock-up piston is fitted slowly to the converter cover under pressure securing smooth lock-
up engagement.


Figure 51. Lock-up Control

DIRECT ELECTRIC SHIFT CONTROL (DESC)
Feature
• Based on each switch signal (low & reverse brake pressure, 2-4 brake pressure & high clutch pressure)
and each sensor signal (turbine sensor, speed sensor, engine speed signal & APP position signal), the
duty cycle type solenoid adjusts the clutch pressure to match the engine load and vehicle travel
conditions. Controlling the engagement and disengagement of the clutch and brake pressure is directly
and accurately controlled via TCM, which is different to the previous accumulator type.
Operation
• Instead of the previous system (on/off type of shift solenoid and shift valve), the combination of the duty
cycle type solenoid and the amplifier (Amp) valve are used to adjust the clutch pressure to match the
engine load and vehicle travel conditions, based on the signal from the TCM. Also, the pressure switch
provided in the oil passage of the control valve transmits the oil pressure condition (at that time) to TCM,
enabling the engagement and disengagement control of the clutch and brake to be directly and finely
carried out.
• 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
pressures on the engagement side and disengagement side are simultaneously controlled.
As a result, engine racing or clutch drag is prevented which enables a smooth and quick shift response.


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