2007 ISUZU KB P190 low oil pressure

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 position 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.

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ISUZU KB P190 2007

7A2-16 TRANSMISSION CONTROL SYSTEM (JR405E)
Transmission Fluid Passages (Main Unit)
Legend1. 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. High clutch pressure detection port
5. 2-4 brake pressure detection port
6. Oil cooler (inlet)
7. Oil cooler (outlet)
8. High clutch pressure detection passage
9. Oil pump passage (outlet)
10. Reverse clutch passage 11. High clutch passage 12. Front lubrication passage
13. 2-4 brake passage
14. Oil pump passage (inlet)
15. Torque converter passage (when not in lock up
control)
16. Torque converter passage (when in lock up control)
17. Oil cooler passage (inlet)
18. 2-4 brake pressure detection passage
19. Extension lubrication passage
20. Low clutch passage
21. Rear lubrication passage
22. Low & reverse brake passage
23. Low & reverse brake pressure detection passage

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ISUZU KB P190 2007

7A2-24 TRANSMISSION CONTROL SYSTEM (JR405E)
Scan Tool Data List
The Transmission Scan Tool Data List contains all
transmission related parameters that are available on
the scan tool. Use the Transmission Scan Tool Data
List only after the following is determined:
• The Transmission Controls - Diagnostic System Check is completed. • On-board diagnostics are functioning properly.
Scan tool values from a properly running engine may
be used for comparison with the transmission you are
diagnosing. The Transmission Scan Tool Data List
represents values that would be seen on a normal
running engine. Only the parameters listed below are
referenced in this service manual for use in diagnosis.
Scan Tool Parameter Units DisplayedTypical Data
Operating Conditions: Engine idle/ Engine coolant temperature is between 75 to 85 °C (167 to 185 °F)/ Accelerator pedal is not
pressed/ Park range/ Transfer case is 2H position/ Accessories OFF
Accelerator Pedal Position %0%
Engine Speed RPMNearly 700 RPM
AT Input Speed (Automatic Transmission) RPM600 to 700 RPM
TCC Slip Speed (Torque Converter Clutch) RPMLess than 100 RPM
AT Output Speed (Automatic Transmission) RPM0 RPM
Vehicle Speed km/h/ MPH0 km/h / MPH
Current Gear 1st/ 2nd/ 2nd L-Up/ 3rd/ 3rd
L-Up/ 4th/ 4th L-Up 1st
Estimated Gear Ratio : 132.77:1
Transmission Range (TR) Park/ Neutral/ Reverse/
Drive/ Drive 3/ Drive 2/ Drive 1 Park
TR Switch P (Transmission Range) On/ OffOn
TR Switch R (Transmission Range) On/ OffOff
TR Switch N (Transmission Range) On/ OffOff
TR Switch D (Transmission Range) On/ OffOff
TR Switch 3 (Transmission Range) On/ OffOff
TR Switch 2 (Transmission Range) On/ OffOff
TR Switch L (Transmission Range) On/ OffOff
PCS Command (Pressure Control Solenoid) On/ OffOn
Low & Reverse Brake Solenoid Command %100%
Low & Reverse Brake Pressure Switch On/ OffOff
2-4 Brake Solenoid Command %100%
2-4 Brake Pressure Switch On/ OffOff
High Clutch Solenoid Command %100%
High Clutch Pressure Switch On/ OffOff
Low Clutch Solenoid Command %0%
TCC Solenoid (Torque Converter Clutch) %5%
Transmission Fluid Temperature °C/ °F V arie s
Transmission Oil Temperature Lamp On/ OffOff
TCM Status Temp. (Temperature Transmission Control Module) Low/ HighLow
4 Wheel Drive Low On/ OffOff
TCM Status Transfer (Transmission Control Module) Low/ HighHigh
TCM Status Down Slope (Transmission Control Module) On/ OffOff

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ISUZU KB P190 2007

7A2-26 TRANSMISSION CONTROL SYSTEM (JR405E)
Low & Reverse Brake Pressure Switch
This parameter displays the input state of the low &
reverse brake transmission fluid pressure (TFP) switch
to the TCM. When the low & reverse brake fluid
pressure is generated, the scan tool displays On.
2-4 Brake Solenoid Command
This parameter displays the 2-4 brake solenoid valve
control duty ratio based on the command from the
TCM. The scan tool will display a lower percentage
when the 2-4 brake is controlled to engage (fluid
pressure is applied to the 2-4 brake hydraulic circuits).
The scan tool will display higher percentage when the
2-4 brake is controlled to disengage (fluid pressure is
drained from the 2-4 brake hydraulic circuits).
2-4 Brake Pressure Switch
This parameter displays the input state of the 2-4 brake
transmission fluid pressure (TFP) switch to the TCM.
When the 2-4 brake fluid pressure is generated, the
scan tool displays On.
High Clutch Solenoid Command
This parameter displays the high clutch solenoid valve
control duty ratio based on the command from the
TCM. The scan tool will display a lower percentage
when the high clutch is controlled to engage (fluid
pressure is applied to the high clutch hydraulic circuits).
The scan tool will display higher percentage when the
high clutch is controlled to disengage (fluid pressure is
drained from the high clutch hydraulic circuits).
High Clutch Pressure Switch
This parameter displays the input state of the high
clutch transmission fluid pressure (TFP) switch to the
TCM. When the high clutch fluid pressure is generated,
the scan tool displays On.
Low Clutch Solenoid Command
This parameter displays the low clutch solenoid valve
control duty ratio based on the command from the
TCM. The scan tool will display a lower percentage
when the low clutch is controlled to engage (fluid
pressure is applied to the low clutch hydraulic circuits).
The scan tool will display higher percentage when the
low clutch is controlled to disengage (fluid pressure is
drained from the low clutch hydraulic circuits).
TCC Solenoid (Torque Converter Clutch)
This parameter displays the torque converter clutch
(TCC) control duty ratio based on the command from
the TCM. The scan tool will display a lower percentage
when the TCC is controlled to disengage (fluid
pressure is drained from the TCC release hydraulic
circuits). The scan tool will display higher percentage
when the TCC is controlled to engage (fluid pressure is
applied to the TCC apply hydraulic circuits). Transmission Fluid Temperature
This parameter displays the temperature of the
automatic transmission fluid (ATF) temperature as
calculated by the TCM using the signal from the
transmission fluid temperature (TFT) sensor. The scan
tool will display a low temperature when the signal
voltage is high, and a high temperature when the signal
voltage is low.
Transmission Oil Temperature Lamp
This parameter displays the commanded state of the
transmission oil temperature lamp control circuit. The
lamp should be On when the scan tool indicates
command On.
TCM Status Temp. (Temperature Transmission
Control Module)
This parameter displays the commanded state of the
high temperature mode shift map. On indicates the
transmission fluid temperature is high and the high
temperature mode is selected to prevent an
overheating.
4 Wheel Drive Low
This parameter displays the input state of the 4WD low
gear signal from the transfer case control module
(TCCM). When the 4L mode is selected, the scan tool
displays On.
TCM Status Transfer (Transmission Control
Module)
This parameter displays the commanded state of the
shift map that is based on the transfer case position.
High indicates the high mode (2H or 4H) is inputted
from the transfer case control module (TCCM). Low
indicates the low mode (4L) is inputted from the TCCM.
TCM Status Down Slope (Transmission Control
Module)
This parameter displays the commanded state of the
down slope mode shift map. On indicates the down
slope mode is selected under certain driving conditions.
TCM Status Up Slope (Transmission Control
Module)
This parameter displays the commanded state of the
up slope mode shift map. On indicates the up slope
mode is selected under certin driving conditions.
3rd Start Switch
This parameter displays the input state of the 3rd start
switch to the TCM. When the switch is pressed, the
scan tool displays On.
3rd Start Lamp
This parameter displays the commanded state of the
3rd start lamp control circuit. The lamp should be On
when the scan tool indicates command On.

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TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-27
Power Drive Switch
This parameter displays the input state of the power
drive switch to the TCM. When the switch is pressed,
the scan tool displays On.
Power Drive Lamp
This parameter displays the commanded state of the
power drive lamp control circuit. The lamp should be
On when the scan tool indicates command On.
Brake Pedal Switch
This parameter displays the input state of the brake
pedal switch to the TCM. When the pedal is depressed,
scan tool displays On. Diagnostic Switch
This parameter displays the input state of the
diagnostic request switch to the TCM. When the data
link connector (DLC) terminal 11 is pulled low, the
check trans lamp blinks to indicate flash code.
Check Trans Lamp
This parameter displays the commanded state of the
check trans lamp control circuit. The lamp should be
On when the scan tool indicates command On.
Scan Tool Output Controls
Scan Tool
Output Control Descriptions
Lamp control Power Lamp Te s tThe purpose of this test is for checking whether the power drive lamp is operating when
commanded ON. Faulty circuit(s) or an open circuit could be considered when not
operating when commanded ON.
Lamp control 3rd Start Lamp Te s t The purpose of this test is for checking whether the 3rd start lamp is operating when
commanded ON. Faulty circuit(s) or an open circuit could be considered when not
operating when commanded ON.
Lamp control AT Oil Temperature
Lamp Test The purpose of this test is for checking whether the AT oil temperature lamp is operating
when commanded ON. Faulty circuit(s) or an open circuit could be considered when not
operating when commanded ON.
Lamp control Check Light Te s t The purpose of this test is for checking whether the check trans lamp is operating when
commanded ON. Faulty circuit(s) or an open circuit could be considered when not
operating when commanded ON.
Solenoid valve control Low & Reverse
Brake Solenoid The purpose of this test is for checking whether the low & reverse brake solenoid valve is
operating when commanded ON. Faulty circuit(s) or a faulty solenoid valve could be
considered if not energizing when commanded ON.
Solenoid valve control 2-4 Brake
Solenoid Test The purpose of this test is for checking whether the 2-4 brake solenoid valve is operating
when commanded ON. Faulty circuit(s) or a faulty solenoid valve could be considered if
not energizing when commanded ON.
Solenoid valve control High Clutch
Solenoid Test The purpose of this test is for checking whether the high clutch solenoid valve is operating
when commanded ON. Faulty circuit(s) or a faulty solenoid valve could be considered if
not energizing when commanded ON.
Solenoid valve control Low Clutch
Solenoid Test The purpose of this test is for checking whether the low clutch solenoid valve is operating
when commanded ON. Faulty circuit(s) or a faulty solenoid valve could be considered if
not energizing when commanded ON.
Solenoid valve control Pressure
Control
Solenoid (PCS) The purpose of this test is for checking whether the pressure control (PC) solenoid valve is
operating when commanded ON. Faulty circuit(s) or a faulty solenoid valve could be
considered if not energizing when commanded ON.
Solenoid valve control TCC Solenoid
Te s t The purpose of this test is for checking whether the torque converter clutch (TCC) solenoid
valve is operating when commanded ON. Faulty circuit(s) or a faulty solenoid valve could
be considered if not energizing when commanded ON.

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7A2-52 TRANSMISSION CONTROL SYSTEM (JR405E)
DTC P0731, P0732, P0733 or P0734 (Flash Code 41, 42, 43 or 44)
Circuit Description
The TCM calculates the gear ratio based on the input
shaft speed signal from the input shaft speed (ISS)
sensor and the output speed signal from the output
shaft speed (OSS) sensor. The TCM compares the
known transmission gear ratio to the calculated ratio for
the selected gear ranges. If the TCM detects an
unknown transmission gear ratio two consecutive
driving cycles, this DTC will set.
Condition for Running the DTC • Other than DTCs P0731, P0732, P0733 and P0734 are not set.
• The ignition switch is ON.
• The transmission fluid temperature is more than 60 °C (140 °F).
• The input shaft speed is more than 1000 RPM.
• The vehicle speed is more than 10 km/h (6 MPH).
• The selector lever is forward range for longer than 2 seconds.
• The TCM is not under gearshift control.
Condition for Setting the DTC • The TCM detects that the output shaft speed is more than 500 RPM over the calculated speed
(based on the input shaft speed and the gear ratio)
for 7 seconds after each gearshift has completed.
Action Taken When the DTC Sets • The TCM blinks the Check Trans lamp on the second consecutive driving cycle when the
diagnostic runs and fails.
Condition for Clearing the DTC • The TCM turns OFF the Check Trans lamp when the diagnostic runs and does not fail. • A current DTC clears when the diagnostic runs and
does not fail.
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
• Electromagnetic interference in the ISS sensor or OSS sensor circuits may set this DTC.
• An intermittent ISS sensor or OSS sensor signal pulse may set this DTC.
• Ensure the ISS sensor and OSS sensor is tight.
• Use the Clutch, Brake, Solenoid and Pressure Switch Logic table to verify each component works
properly within the selected gear range.
• A transmission mechanical problem will cause this DTC to set.
• Sticking or contamination of shift valves may cause intermittent incorrect gear ratios.
• If multiple incorrect gear ratio codes are set, problem in fluid pressure, low ATF level, plugged
filter or oil pump problem may exist.
Notice: • Each DTC agrees with the following gear positions.
- P0731: 1st gear
- P0732: 2nd gear
- P0733: 3rd gear
- P0734: 4th gear
Schematic Reference: Transmission Controls
Schematics
Connector End View Reference: Transmission
Controls Connector End Views or TCM Connector End
Views
Circuit/ System Testing DTC P0731, P0732, P0733 or P0734
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Transmission Controls? —
Go to Step 2 Go to Diagnostic
System Check - Transmission Controls
2 Perform the ATF level check. Refer to repair
instructions (On-Vehicle Service).
Did you perform the ATF level check? —
Go to Step 3 Go to Transmission
Fluid Checking Procedure
3 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Drive the vehicle while observing the DTC Information with a scan tool.
Is there any DTCs set other than P0731, P0732,
P0733 or P0734? —
Refer to Applicable DTC Go to Step 4

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7A2-72 TRANSMISSION CONTROL SYSTEM (JR405E)
41. Remove the transmission oil pan. Refer to
repair instructions (On-Vehicle Service).
2. Inspect the low & reverse brake solenoid valve and transmission fluid pressure (TFP) switch
for the following conditions:
• Physical damage
• Loose or improper installation
3. Test the signal circuit between the low & reverse brake TFP switch and the in-line
harness connector (pin 12 of E-54 male side)
for a short to ground.
4. Repair the circuit(s) or replace as necessary.
Did you find and correct the condition? —
Go to Step 7 Go to Step 5
5 1. Remove the low & reverse brake solenoid
valve and TFP switch from the valve body
assembly and perform function check. Refer
to repair instructions (On-Vehicle Service).
2. Repair or replace as necessary.
Did you find and correct the condition? —
Go to Step 7 Go to Step 6
6 Repair or replace the valve body assembly. Refer
to repair instructions (On-Vehicle Service or Unit
Repair).
Did you complete the repair or replacement? —
Go to Step 7 —
7 1. Reconnect all previously disconnected
components or harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Drive the vehicle while observing the DTC Information with a scan tool.
Did the DTC fail this ignition? —
Go to Step 2 Go to Step 8
8 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No

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7A2-74 TRANSMISSION CONTROL SYSTEM (JR405E)
41. Remove the transmission oil pan. Refer to
repair instructions (On-Vehicle Service).
2. Inspect the 2-4 brake solenoid valve and transmission fluid pressure (TFP) switch for
the following conditions:
• Physical damage
• Loose or improper installation
3. Test the signal circuit between the 2-4 brake TFP switch and the in-line harness connector
(pin 7 of E-54 male side) for a short to ground
4. Repair the circuit(s) or replace as necessary.
Did you find and correct the condition? —
Go to Step 7 Go to Step 5
5 1. Remove the 2-4 brake solenoid valve and TFP
switch from the valve body assembly and
perform function check. Refer to repair
instructions (On-Vehicle Service).
2. Repair or replace as necessary.
Did you find and correct the condition? —
Go to Step 7 Go to Step 6
6 Repair or replace the valve body assembly. Refer
to repair instructions (On-Vehicle Service or Unit
Repair).
Did you complete the repair or replacement? —
Go to Step 7 —
7 1. Reconnect all previously disconnected
components or harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Drive the vehicle while observing the DTC Information with a scan tool.
Did the DTC fail this ignition? —
Go to Step 2 Go to Step 8
8 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No

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ISUZU KB P190 2007