Isuzu KB P190. Manual - part 994

7A2-10  TRANSMISSION CONTROL SYSTEM (AW30–40LE) 

CHECK ITEM 

PIN No. 

VALUE 

NOTE 

Shift Solenoid B (S2) 

C-94: 15–1 

P 

0V 

Engine run. 

 

 

R 

0V 

Engine run. (Without the 
Reverse position lock out) 

 

 

N 0V 

Engine 

run. 

 

 

D–1 0V 

 

 

 

D–2 VIGN 

 

 

 

D–3 VIGN 

 

 

 

D–4 0V 

 

Lock-up Solenoid 

C-94: 5–1 

“ON” 

VIGN 

(ex.) It is “ON” when the 
vehicle speed is more than 
65km/h. 

 

 

“OFF” 0V 

 

Check Trans Lamp 

C-95: 3–C-94: 1 

“ON” 

0V 

Key “ON” 

(The lamp is “ON” for 3 
second after key “ON”) 

 

 

“OFF” VIGN 

 

AT Oil Temperature Lamp 

C-95: 11–C-94: 1 

“ON” 

0V 

Key “ON” 

(The lamp is “ON” for 3 
second after key “ON”) 

 

 

“OFF” VIGN 

 

Power Lamp 

C-95: 2–C-94: 1 

“ON” 

0V 

Key “ON” 

(The lamp is “ON” when the 
Power switch is “ON”) 

 

 

“OFF” VIGN 

 

3rd Start Lamp 

C-95: 10–C-94: 1 

“ON” 

0V 

Key “ON” 

(The lamp is “ON” when the 
3rd Start switch is “ON”) 

 

 

“OFF” VIGN 

 

AT Oil Temp Sensor 
Resistance 

C-94: 11–C-94: 12

20

°C/68°F 

12k

Ω 

Key “OFF” 

 

 

50

°C/122°F 1.5k

Ω

 

 

 

 

155

°C/311°F 293

Ω 

 

Pressure Control Solenoid 
Resistance 

C-94: 11–C-942 

About  

4–7

Ω

(20

°C/68°F) 

 

Key “OFF” 

Speed Sensor Resistance 

C-95: 5–C-95: 14 

About 560

Ω

– 

120

Ω

(20

°C/68°F) 

 

Key “OFF” 

Input Revolution Sensor 
Resistance 

C-95: 6–C-95: 16 

About 560

Ω

– 

120

Ω

(20

°C/68°F) 

 

Key “OFF” 

Lock-up Solenoid 
Resistance 

C-94: 5–C-94: 1 

About 10

Ω

– 

15

Ω

(20

°C/68°F) 

 

Key “OFF” 

Shift Solenoid A (S1) 
Resistance 

C-94: 16–C-94: 1 

About 10

Ω

– 

15

Ω

(20

°C/68°F) 

 

Key “OFF” 

Shift Solenoid B (S2) 
Resistance 

C-94: 15–C-94: 1 

About 10

Ω

– 

15

Ω

(20

°C/68°F) 

 

Key “OFF” 

TRANSMISSION CONTROL SYSTEM (AW30–40LE)  7A2-11 

Control System Diagram 

 

 

 

RTW77AXF000301 

7A2-12  TRANSMISSION CONTROL SYSTEM (AW30–40LE) 

Control and Functions 

 

Item Description 

Shift and lock-up control 

Shift and lock-up points can be controlled in accordance with output of S1, S2, and 
SL solenoids based on "Shift-map" made up of vehicle speed and the opening. 

Overdrive off cut control 

When the select lever is operated from D to 3, if the vehicle speed is more than 
142km/h (89mph), TCM enables to remain overdrive in order to prevent over rev. 

Lock-up cut control 

Lock-up is inhibited with following condition in order to improve the shift feeling. 

• 1st 

gear 

• Idling 
•  Operating brake switch 
• L 

position 

•  During shift change 

Driveng mode select control 

•  The TCM selects a suitable driving mode from the ten kinds for the variety

driving condition. 

1) Normal mode 

2) Power mode 

3)  3rd start mode 

4) HOT mode 

5) L4 mode 

6)  Up slope1 mode 

7)  Up slope2 mode 

8)  Down slope mode 

9)  Auto cruise mode 

10) Warm up mode 

•  The priority of driving mode 

Normal < Power < Up slope1 < Up slope2 < Down slope < L4 < Warm up < Auto 
cruise < 3rd start < HOT 

Oil temperature compensation 
control 

If the ATF temperature exceeds 130

°C (266°F), the TCM selects the HOT mode 

shift pattern for lock-up, thus preventing the oil temperature from rising. (The HOT 
mode is released, if the ATF temperature is less than 115

°C /239°F.) 

3rd start mode control 

By selecting 3rd start mode, the vehicle starting can be controls smoothly on low 
frictional road like a snowy or muddy. 

1. Enable 

condition 

a)  The gear select position is "D" only. 

b)  Vehicle speed is less than 11km/h (7mph). 

c)  Transmission oil temperature is less than 120

°C (248°F). 

d)  Accelerator opening is less than 8%. 

e)  Except 3rd start mode. 

2. Disable condition 

a)  Turning off the 3rd start mode switch 

b)  Shifting select position to "3", "2", or "L"(3rd start mode is not canceled by

selecting "N", "R", or "P") 

c)  Ignition key is turned off. 

d)  Vehicle speed is more than 35km/h (22mph). 

L4 mode control 

The TCM detects whether the transfer is engaged in high or low based on L4 switch 
signal, and selects the "Shift-map". 

TRANSMISSION CONTROL SYSTEM (AW30–40LE)  7A2-13 

Item Description 

Reverse lock out control 

If the select lever is moved to "R" position during forward driving, the TCM prohibits 
reverse driving by turn off the S1 and turn on the S2 for prevention of danger and 
protection of the automatic transmission. 

1. Enable condition 

a)  Vehicle speed is more than 11km/h (7mph). 

2. Disable condition 

a)  Vehicle speed is less than 9km/h (6mph). 

b)  When except "R" position is detected. 

Auto cruise mode control 

If the auto cruise control can’t keep the setting speed like a uphill driving, the TCM 
selects the auto cruise mode shift pattern for downshifting, thus keeping the vehicle 
speed. 

Warm-up 

mode 

control 

TCM selects the warm-up mode shift pattern in engine cold condition for 
improvement of drivability and facilitation of warm-up. 

Squat control 

When the TCM detects N→D garage shift, the TCM controls 1-3-1 shift by setting 
timer, in order to improve the shift feel at N→D. 

Coast down control 

The TCM switches to the coast down control at the coasting, in order to reduce the 
roughness of shifting. 

Uphill control 

When the TCM detected uphill, the TCM automatically switches to the uphill mode 
in two-stage in proportion to inclination pitch to prevent the busy shifting and to 
obtain an enough torque. 

Downhill control 

When the TCM detected downhill, the TCM automatically switches to the downhill 
mode, and shifts to the 3rd or keeps in the 3rd in order to prevent the vehicle 
acceleration. Then, the brake load is reduced by a moderate engine brake and fuel 
consumption is improved by the fuel cut.  

Line pressure control 

The TCM controls the impressed current of the pressure control solenoid based on 
the throttle opening, and regulates suitable throttle pressure. 

Engine truque management 
control 

The TCM controls engine torque for improvement of shift quality or durability under 
the following conditions. 

•  Upshift and downshift 
• Garageshift 

Indicate driving mode function  The TCM indicates the following driving mode on instrument panel. 

•  Power mode 
•  3rd start mode 

Indicate oil temperature 
warning function 

If the transmission oil temperature sensor senses that transmission oil temperature 
is greater than 146

°C (295°F), the TCM turns on ATF warning lamp. (The warning 

lamp is turned off, if oil temperature is less than 126

°C/259°F.) 

Fail-safe function 

When trouble occurs to vehicle sensor and each solenoid, TCM automatically exerts 
fail-safe control not to spoil driveability. 

•  This control is exerted when sensor or actuator is in trouble, while TCM works 

normally. 

•  The "CHECK TRANS" light flashes to alert the driver, and the transmission 

must be manually shifted as follows. 

 

Select lever position 

Gear position 

D 4 

(Fourth) 

3 4 

(Fourth) 

2 3 

(Third) 

L 3 

(Third) 

R Reverse 

 

 

Shift are firmer to prevent clutch slip and consequent wear. The fault should be 
corrected as soon as possible.