Isuzu KB P190. Manual — part 1101

7A2-120 TRANSMISSION CONTROL SYSTEM (JR405E)

Z7: Shift Indicator is Faulty

Z8: Transmission Fluid is Splashed During Running

Z9: Abnormal Smell

Z10: Transmission Fluid Quantity is Low or High

Z11: Abnormal Transmission Fluid Pressure

Checks

Action

Definition:
Shift indicator does not change even though the selector lever is moved.

Diagnosis

Hints

Inspect the transmission range switch and selector lever cable for
misadjusting or disordering. Refer to On-Vehicle Service section.

Checks

Action

Definition:
Transmission Fluid is splashed during running.

Diagnosis Hints

Transmission fluid quantity is excessively high.

Checks

Action

Definition:
Abnormal smell.

Diagnosis Hints

A trouble in the transmission main unit.

Checks

Action

Definition:
Transmission fluid quantity is low or high.

Diagnosis Hints

• If the fluid level is high, level check might be performed at low

temperature.

• If the fluid level is low, fluid leak is suspected.

Checks

Action

Definition:
Transmission fluid pressure (TFP) is low or high.

Diagnosis Hints

• Faulty pressure control (PC) solenoid valve or hydraulic circuits.

• If pressure is low, faulty oil pump is suspected.

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-121

Test Instructions

Line Pressure Test

Legend

1. Oil cooler (outlet)
2. Low & reverse brake pressure detection port (R range

line pressure detection port)

3. Low clutch pressure detection port (D, 3, 2, L range

line pressure detection port)

4. Oil cooler (inlet)

Line Pressure Test Procedure

1. Fully apply the parking brake and chock all wheels.

2. Check the level of the engine oil, coolant and

transmission fluid. Replenish as necessary.

3. Remove the plug from either of the line pressure

detection port (low & reverse brake pressure
detection port or low clutch pressure detection
port).

4. Install a pressure gauge to the line pressure

detection port.

5. Start the engine and warm up (allow engine

coolant temperature to reach at least 70

°C

[158

°F]).

Important: Keep the brakes applied at all times in
order to prevent unexpected vehicle motion. Personal
injury may result if the vehicle moves unexpectedly.

6. Let idle and record the line pressure when the

selector lever is positioned R or D, 3, 2 and L
range.

Important: Line pressure test at the stall speed must
be finished within 5 seconds. Prolonged test time may
break the transmission.

7. Fully depress the brake pedal with your left foot.

8. Move the selector lever to the R or D range and

fully depress the accelerator pedal. Record the line
pressure as soon as the stall speed.

9. Move the selector lever to the N range and let idle

for at least 1 minute.

10. If the pressure gauge is connected to the low

clutch pressure detection port, repeat the line
pressure test (step 7 to 9) at the stall speed in 3, 2
and L range.

11. Turn OFF the ignition.

12. Disconnect a pressure gauge from the line

pressure detection port.

13. Tighten the plug.

1

2

3

4

7A2-122 TRANSMISSION CONTROL SYSTEM (JR405E)

Standard Value

Diagnosis

1. If the line pressure is lower than the standard value

at idle in all ranges.

• Abraded oil pump.

• Faulty operation of each solenoid valve.

• Sticking of pressure regulator spool valve or pilot

spool valve.

• Fatigued pressure regulator spool valve spring or

pilot spool valve spring.

• Transmission fluid leaking from the oil strainer, oil

pump, pressure regulator spool valve, torque
converter relief spool valve or pressure relief valve.

2. If the line pressure is lower than the standard value

at idle in D, 3, 2 and L range.

• Transmission fluid leaking from the low clutch

hydraulic circuit.

3. If the line pressure is lower than the standard value

at idle in R range.

• Transmission fluid leaking from the reverse clutch

hydraulic circuit.

• Transmission fluid leaking from the low & reverse

brake hydraulic circuit.

4. If the line pressure is lower that the standard value

at idle in L or R range.

• Transmission fluid leaking from the low & reverse

brake hydraulic circuit.

5. If the line pressure is higher than the standard

value at idle in all ranges.

• Faulty accelerator pedal position signal.

• Faulty transmission fluid temperature (TFT)

sensor.

• Faulty operation of low clutch solenoid valve.

• Sticking pilot spool valve.

• Sticking pressure regulator spool valve or plug.

6. If the line pressure is lower than the standard value

at stall speed in all ranges.

• Faulty accelerator pedal position signal.

• Faulty operation of pressure control (PC) solenoid

valve.

• Faulty operation of low clutch solenoid valve.

• Sticking pilot spool valve.

• Sticking pressure regulator spool valve or plug.

Selector lever

position

Engine

speed

Line pressure (kPa/ psi)

D, 3, 2 or D

Idle

350 - 480 / 51 - 70

R

Stall

1050 - 1250 / 152 - 182

Idle

450 - 650 / 65 - 95

Stall

1400 - 1630 / 203 - 237

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-123

Stall Test

Stall Test Procedure

1. Fully apply the parking brake and chock all wheels.

2. Check the level of the engine oil, coolant and

transmission fluid. Replenish as necessary.

3. Start the engine and warm up (allow engine

coolant temperature to reach at least 70

°C

[158

°F]).

Important: Stall test must be finished within 5 seconds.
Prolonged test time may break the transmission.

4. Fully depress the brake pedal with your left foot.

5. Move the selector lever to the D range and fully

depress the accelerator pedal. Record the engine
speed as soon as the stall speed.

6. Move the selector lever to the N range and let idle

for at least 1 minute.

7. Repeat the stall test (step 4 to 6) in R, 3, 2 and L

range.

Standard Value

Diagnosis

1. If the stall speed is higher than the standard value

in all ranges.

• Low line pressure.

• Abraded oil pump.

• Faulty operation of low clutch.

• Faulty transmission range switch.

• Transmission fluid leaking from the oil pump, valve

body or transmission case.

• Sticking of pressure regulator spool valve or pilot

spool valve.

2. If the stall speed is higher than the standard value

in D, 3, 2 and L ranges.

• Slipping of low clutch

• Slipping of low one-way clutch

3. If the stall speed is higher than the standard value

in R range.

• Slipping of low & reverse brake

• Slipping of reverse clutch

4. If the stall speed is lower than the standard value is

all ranges.

• Slipping of torque converter one-way clutch

• Problem in engine

Stall speed

Pre condition

2050

± 150 RPM

Ambient temperature between 10

and 40

°C [50 and 104°F]