2004 ISUZU TF SERIES low oil pressure

7A2-10 TRANSMISSION CONTROL SYSTEM (AW30 –40LE) (V6 3.5L)

Control and Functions
Shift Control
The transmission gear is shifted according to the shift
pattern selected by the driver. In shifting gears, the
gear ratio is controlled by the ON/ OFF signal using the
shift solenoid S1 and the shift solenoid S2.
Band Apply Control
The band apply is controlled when in the 3 –2 downshift
(engine overrun prevention) and the garage shift (shock
control).
The band apply solenoid is controlled by the signal from
the Pulse Width Modulation (PWM) to regulate the flow
of the oil.
Torque Converter Clutch Control
The clutch ON/OFF is controlled by moving the
converter clutch valve through shifting Torque
Converter Clutch (TCC) solenoid using the ON/OFF
signal.
Line Pressure Control
The throttle signal allows the current signal to be sent
to the force motor. After receiving the current signal,
the force motor activates the pressure regulator valve
to regulate the line pressure.
On –Board Diagnostic System
Several malfunction displays can be stored in the
Transmission Control Module (TCM) memory, and read
out of it afterward.
The serial data lines, which are required for the testing
of the final assembly and the coupling to othe
r
electronic modules, can be regulated by this function.
Fail –Safe Mechanism
If there is a problem in the transmission system, the
TCM will go into a “backup" mode.
The vehicle can still be driven, but the driver must use
the select lever to shift gears.
Torque Management Control
The transmission control side sends the absolute spark
advance signal to the engine control side while the
transmission is being shifted. This controls the engine
spark timing in compliance with the vehicle running
condition to reduce the shocks caused by the change o
f
speed.
ATF Warning Control
The oil temperature sensor detects the ATF oil
temperature to control the oil temperature warning,
TCC, and the 3rd start mode.
Reverse Lock Out Control
With the selector lever in reverse position, the TCM will
not close the PWM solenoid until the vehicle is below
15 km/h (9.3 mph), thus preventing reverse
engagement above this speed.

Downhill Control
This mode is automatically activated from NORMAL
mode only when downhill conditions are recognized.
The shift pattern is identical to NORMAL mode except
3-4 and 4-3 shift lines at low throttle modified to get
engine braking on a larger speed range.
Uphill Control
When uphill condition are recognized the 2-3 and 3-4
shift and TCC apply are down only when the engine
torque is sufficient in order to avoid shift hunting.
Gear Shift Control 3rd start


SELECT LEVER RANGE SHIFT PATTERN
D(Drive) 1


2TCC

3TCC

4TCC
3(Third) 1

2TCC

3TCC
2(Second) 1

2(
3)
L(First) 1(
2)
TCC: Torque Converter Clutch
(Notice1): “( )" means over-revving prevention control.
Mode Type


Mode Type Select lever position
Normal drive mode
(NOR) Entire range (excluding “R")
Power drive mode
(PWR) Entire range (excluding “R")

Mode Selection



SWITCH(SW) LAMP
Mode Type PWR/N
OR.S 3RD
START SW POWER
DRIVE LAMP 3RD
START LAMP
Normal
drive mode
(NOR) OFF OFF OFF OFF
Power
drive mod
(PWR) ON OFF ON OFF
3rd Start
mode OFF ON OFF ON
However, the 3rd start switch prevails over the
PWR/NOR switch.
The mode become normal drive mode when the 3rd
start switch is operated from ON to OFF.

7A2-12 TRANSMISSION CONTROL SYSTEM (AW30 –40LE) (V6 3.5L)

Functions of Input / Output Components
Component Function
Transfer low signal Detects the transfer High/Low position.
OD Cancel signal Detects whether the cruise control unit is judged OD cancel mode.
Output revolution sensor
(Transmission) Detects the vehicle speed.
Input revolution sensor
(Transmission) Detects the input revolution (OD direct clutch drum revolution).
Engine revolution sensor Detects the engine revolution with CAN.
Throttle position signal Detects the throttle opening rate with CAN.
Neutral start switch Detects the select lever position.
Pattern select switch Detects whether the driver has selected "NORMAL" or "POWER" mode.
Brake lamp switch Detects whether the driver has pressed the brake pedal or not.
Oil temperature sensor Detects the oil temperature.




I
n
p
u t
Diagnostic start switch Starts self-diagnosis and displays a code for faulty part if any.
I
n
p
u t
/
O
u t
p
u t Data link connector When connected with Tech2 or tester, can communicate the data for function
check, etc.
Shift solenoid S1, S2 Selects shift point and gear position suited to the vehicle running condition on the
basis of TCM output.
Lock-up control solenoid SL Control the lock-up clutch suited to the vehicle running condition on the basis of TCM output.
Pressure control solenoid
STH Adjusts throttle pressure by energizing current of linear pressure control solenoid
to prevent the shift shock and to obtain shift smoothly.
"CHECK TRANS" lamp When trouble has occurred to throttle position sensor, vehicle speed sensor, or
solenoid, "CHECK TRANS" lamp is blinked to warn the driver. If also displays the
trouble code.
A/T OIL TEMP warning
lamp Lights when ATF oil temperature rises. (Turned on at greater than 146


C
(295

F). Turned off at less than 132

C (270

F).
POWER lamp Lights when POWER MODE detected.



O
u
t
p
u
t
3rd Start lamp Lights when 3rd Start MODE detected.
C
o
m
p
u t
e r Transmission Control
Module (TCM) Based on the signal from each switch and sensors, judges necessary shift point
and lock-up operation, and send signal to each solenoid.

7A2-20 TRANSMISSION CONTROL SYSTEM (AW30 –40LE) (V6 3.5L)




RTW37ALH000101

Once the test vehicle has been identified an
“ Application (Powertrain) Menu" screen appears.
Please select the appropriate application.
The following table shows, which functions are used fo
r
the available equipment versions.



F0: Diagnostic Trouble Codes

F0: Read DTC Info As stored By ECU

F1: Clear DTC Information

F2: DTC Information
F1: Data Display
F2: Snap Shot
F3: Miscllaneous Tests

F0: Lamps

F0: Power Lamp Test
F1: 3rd start Lamp Test
F2: AT Oil Temperature Lamp
F3: Check Light
F1: Solenoids

F0: Shift solenoid A (S1)
F1: Shift Solenoid B (S2)
F2: Pressure Control Solenoid (PCS)

7A2-22 TRANSMISSION CONTROL SYSTEM (AW30 –40LE) (V6 3.5L)

TRANSMISSION DATA
ITEM UNIT ENGIN RUNNING AT IDLE
Current Gear 1 st/2 nd/3 rd/4 th 1 st
Target Gear 1 st/2 nd/3 rd/4 th 1 st
Vehicle Speed km/h 0 km/h
AT Output Speed (Automatic Transmission) RPM 0 RPM
AT Input Speed (Automatic Transmission) RPM 675725 RPM
Engine Speed RPM 675725 RPM
Throttle Position Sensor Signal % 0.007.00%
AT Oil Temperature (Automatic Transmission) C Depends on conditions
TCM Status Transfer Low /Transfer High Transfer HI
Desired PC Solenoid Pressure (STH) kPa 34.397.0 kPa
Desired PC Solenoid Current (STH) mA 8351020 mA
PC Solenoid Actual Current (STH) mA 8351020 mA
Gear Ratio : 1 Depends on uper hood
TCC Slip Speed RPM 0 RPM
Shift Position Actual P/R/N/L/2/3 P
Inhibitor Switch P/R/N/L/2/3 P
Transmission Check Light On/Off Off
AT Oil Temperature Lamp (Automatic
Transmission) On/Off Off
3 rd Start Lamp On/Off Off
Power Lamp On/Off Off
Shift Solenoid S1 On/Off On
Shift Solenoid S2 On/Off On
Shift Solenoid S3 On/Off Off
Diag Switch Condition On/Off Off
Power Switch On/Off Off
Brake Switch On/Off Off
Cruise Switch On/Off Off
4L Signal On/Off Off
3 rd Start Switch On/Off Off
Coolant Temperature C Depends on conditions
Torque Request (timing Retard) CA 0 CA
Garage Shift Mode On/Off Off
CAN TPS % 0.00%
CAN Signal Valid Counter (ECM)
— 0  255
CAN Signal Valid Counter (TCM) — 0  255

7A2-34 TRANSMISSION CONTROL SYSTEM (AW30 –40LE) (V6 3.5L)

TCM Diagnostic Trouble Codes
The following table lists the diagnostic trouble codes supported by this vehicle application. If any DTCs not listed here
are displayed by a scan tool, the scan tool data may by faulty; notify the scan tool manufacture of any DTCs
displayed that are not included in the following table.
DTC
NUMBER FLASH
CODE DTC NAME
“CHECK
TRANS"
P0560 25 System Voltage Error —
P0602 63 Transmission Control Module (TCM) Programming Error —
P0705 17 Transmission Range Sensor Circuit Malfunction ON
P0712 15 Transmission Oil Temperature Sensor Circuit Low Input ON
P0713 16 Transmission Oil Temperature Sensor Circuit Hight Input ON
P0717 14 Input Speed Sensor Signal Error ON
P0722 11 Output Speed Sensor Signal Error ON
P0743 33 Torque Converter Clutch Electrical ON
P0748 35 Pressure Control Solenoid Electrical ON
P0753 31 Shift Solenoid S1 Electrical ON
P0758 32 Shift Solenoid S2 Electrical ON
P1767 67 ECM CAN (Control Area Network) Invalid ON
P1790 61 Transmission Control Module ROM Checksum Error ON
P1791 62 Transmission Control Module RAM Error ON
U2104 65 CAN (Control Area Network) BUSS OFF ON

7A3-14 ON-VEHICLE SERVICE (AW30 –40LE)

Measure Time Lag
1. Fully apply the parking brake.
2. Start the engine. Check idling speed (A/C OFF).
3. Shift the shift lever from “N" to “D" range. Using a
stopwatch, measure the time it takes from shifting
the lever until the shock is felt.
Time lag: Less than 0.7 seconds
4. In same manner, measure the time lag for “N"


“R".
Time lag: Less than 1.2 seconds
Evaluation
1. If “N" 
“ D" time lag is longer than specified:

Line pressure too low
 Forward clutch malfunction
 No.2 one-way clutch not operating properly
2. If “N" 
“ R" time lag is longer than specified:

Line pressure too low
 Direct clutch malfunction
 No.3 brake malfunction
3. If both time lag is longer than specified:

Line pressure too low

Hydraulic Test



RUW37ALH000201
Preparation

1. Warm up the transmission fluid.
2. Remove the transmission case test plug and mount the hydraulic pressure gauge.
Oil pressure gauge: J –29770 –A
NOTE: Perform the test at normal operation fluid
temperature (50 – 80 
C or 122 – 176 
F).

ON-VEHICLE SERVICE (AW30 –40LE) 7A3-15

Measure Line Pressure
1. Fully apply the parking brake and chock the four
wheels.
2. Start the engine and check idling rpm.
3. Shift into “D" range, step down strongly on the brake
pedal with your left foot and, while manipulating the
accelerator pedal with the right foot, measure the
line pressures at the engine speeds specified in the
table.
4. In the same manner, perform the test in “R" range.


Line pressure kPa (kg/cm2/psi) Engine
speed “D" range “R" range
Idling 323 – 382
(3.3 – 3.9/47 – 55) 500 – 598
(5.1 – 6.1/73 – 87)
Stall 1,137 – 1,274 (11.6–13.0/165–185) 1,499 – 1,833
(15.3–18.7/218–266)
Evaluation
1. If the measured values at all ranges are higher than
specified:

Pressure control solenoid defective
 Primary regulator valve defective
2. If the measured values at all ranges are lower than
specified:

Primary regulator valve defective
 Oil pump defective
 Pressure control solenoid defective
3. If pressure is low in “D" range only:

“ D" range circuit fluid leakage
4. If pressure is low in “R" range only:

“ R" range circuit fluid leakage
Road Test
NOTE: Perform the test at normal operation fluid
temperature (50 – 80 
C or 122 – 176 
F).
“D" Range Test in “NORMAL", and
“POWER" Pattern Ranges
Shift into the “D" range and hold the accelerator pedal
constant at the 50% and 100% throttle valve opening
positions.
Push in one of the pattern selector buttons and check
the following:

1. 1 –2, 2 –3, 3 –OD and lock-up, up-shifts should take
place, and shift points should conform to those
shown in the automatic shift diagram.


RUA370MH000101




RUA37ASH000101

7A3-26 ON-VEHICLE SERVICE (AW30 –40LE)

Solenoid
Inspection

1. Resistance check

Using an ohmmeter, check the resistance
between each terminals (S1/S2/SL) and body.
Solenoid S1, S2 and lock-up solenoid SL
resistance:
11 – 15






(at 20
 
C)
(Reference) 12 – 16






(at 40
 
C)

Using an ohmmeter, check the resistance
between each terminals (STH) and (STHG).
Pressure control solenoid resistance:
5 – 5.6






(at 20
 
C)
(Reference) 5.4 – 6.1






(at 40
 
C)



220L100001
NOTE: If the pressure control solenoid resistance is not
within speciation, replace the valve body assembly.



2. Operation check
Check the solenoid operation by blowing into an oil
hole as shown in the figure.
Solenoid S1 and S2 (Normal close type)


When battery terminal is disconnected No air leaks
When battery terminal is
connected Air passes through

Lock-up solenoid SL (Normal open type)



When battery terminal is disconnected Air passes through
When battery terminal is
connected No air leaks





244RX00001




244RY00005