2004 ISUZU TF SERIES clutch

7A2-112 DIAGNOSIS (JR405E)
Step Action Yes No
1
Gear ratio trouble diagnosis.
Travel in the following sequence for about 7 seconds or more in
each range: Start in the L range (1st) to 2 range (2nd) to 3 range
(3rd) to D range (4th) (to detect the gear ratio trouble exactly, this
process should be carried out)
Go to Step 2 Go to Step 2
2 Are any DTCs stored?
Go to DTC Chart Go to Step 3
3 Are the quantity, contamination and smell normal?
If the ATF level is
low, replenish up to
the specified level.

Go to Step 4
If ATF is extremely
black and
contaminated and
smells burnt, slip of
the clutch is
supposed.
Overhaul the AT
unit.
4 Are the engine speed and other engine system correct?
Go to Step 5
Repair the defect or
replace.
5 Inspection of electrical or mechanical fault
Is the signal from each pressure switch changed synchronously?
Control Valve

TCM
B1
B12
B20 RED/YEL
WHT/BLK 2-4 Brake Pressure SW
Te r m i n a l
Assembly
YEL
E54
(7)
(12)
(1)H23
(12)
(10)C95
(1)
(12)
(20) RED/YEL
YEL
WHT/BLK
L&R Brake Pressure SW
High Clutch Pressure SWH22
(8)
Range TCM terminal
GearB20
(High clutch
pressure SW)B1
(2-4 brake pressure
SW)B12 (Low & reverse
brake pressure SW)
P - More than 10V More than 10V More than 10VR Reverse More than 10V More than 10V -N - More than 10V More than 10V More than 10VD, 3, 2 1st More than 10V More than 10V More than 10V2nd More than 10V - More than 10V3rd - More than 10V More than 10V4th - - More than 10VL 1st More than 10V More than 10V -2nd More than 10V - More than 10V3rd - More than 10V More than 10V4th - - More than 10VGo to Step 6
Repair the defect or
replace.

DIAGNOSIS (JR405E) 7A2-115
No. D1: Faulty Gear Shifting (Different from Shift Pattern)

Description:

Gear is shifted, different from the specified shift pattern.

Diagnosis Hints:

When inspecting faulty gear shifting, it is important to distinguish between the fault of electric system and
mechanical system (AT main unit).

Fault of electric system.
Monitor the output signal (each solenoid driving signal) using with Tech 2. If a trouble signal is sent to the solenoid synchronously with the faulty gear shifting, the fault is originated in the electric system.
Monitor the input signal (signal from each sensor) using with Tech 2 and find an input signal by which the output signal (each solenoid driving signal) is subjected to fault.
Fault of the electric system may be derived from temperature or vibration. For instance, though the engine is normal while it is cold, fault may occur when the engine is warmed up or vehicle is running.

Fault of mechanical system.
If the gear is incorrectly shifted irrespective of operating signal (ON-OFF) of each solenoid, the faulty is originated from the machine system (AT).
If the clutch slips, ATF smells burnt, contaminated to be black or the stall speed increases.

Possible Cause:

Disordered select cable.

Disordered inhibitor switch.

Slip of clutch.
If slip of clutch is caused, a DTC (gear ratio error) is stored.

Fixing at 3rd position (fail-safe activated)
Since the gear is fixed at the 3rd position because of the fail-safe function, a trouble that "Faulty gear shifting" is resulted. In this case, the DTC is memorized.
When TCM stops operation because of faulty TCM ground, the gear is fixed at the 3rd position because
of a mechanical reason. In this case, no DTC is memorized.







Incorrect properties of throttle opening signal (serial communication) of throttle position sensor.
The throttle opening signal which is sent by serial communication from ECM and TCM is an important
signal for gear shifting. In case of ECM fault or when the throttle position sensor does not issue voltage
signal according to the throttle opening, the gear is not shifted by stepping over the accelerator.
If the output voltage of the throttle position sensor changes freely even though the throttle opening is
constant, the gear is shifted incorrectly.




Faulty speed sensor.

7A2-116 DIAGNOSIS (JR405E)
When signal from the speed sensor becomes out of order, it may be judged a result of changed vehicle
speed and faulty gear shifting may be the causes.







Trouble in control valve body (faulty operation, sticking, clogged oil passage)



Step Action Yes No
1 Dislocation or disordered of select lever.
Does the vehicle move when the brake is released in a position
other than the P range and the vehicle is pushed?
Go to Step 2
Adjust the select
cable.
2 Gear ratio trouble diagnosis.
Travel in the following sequence for about 7 seconds or more in
each range: Start in the L range (1st) to 2 range (2nd) to 3 range
(3rd) to D range (4th) (to detect the gear ratio trouble exactly, this
process should be carried out)
Go to Step 3 Go to Step 3
3 Are any DTCs stored?
Go to DTC Chart Go to Step 4
4 Are the quantity, contamination and smell normal?

If the ATF level is
low, replenish up to
the specified level.

Go to Step 5
If ATF is extremely
black and
contaminated and
smells burnt, slip of
the clutch is
supposed.

DIAGNOSIS (JR405E) 7A2-117
Step Action Yes No
5 Inspection of electrical or mechanical fault
Is signal to each solenoid and pressure switch changed
synchronously to the faulty gear shift?

Control Valve


TCM


B1





B12





B20 RED/YEL
WHT/BLK 2-4 Brake Pressure SW

Terminal
Assembly
YEL
E54

(7)





(12)





(1) H23

(12)





(10)C95

(1)





(12)





(20) RED/YEL
YEL
WHT/BLK
L&R Brake Pressure SW

High Clutch Pressure SW

H22

(8)
Control Valve

TCM
B6
B7
B8
B9
B22 (GND) BLU/BLK
WHT/BLU L&R Brake Solen oid

Te r m i n a l
Assembly
BLK/YEL
RED
2-4 Brake Solenoid

High Clutch Solenoid

Low Clu tch S olen oid

E54
(5)
(9)
(10)
(3)
(11)H23
(11)
(5)
(7)
(2)
(1)
GRY/REDC95
(6)
(7)
(8)
(9)
(22) BLU/BLK
BLK/YEL
RED
WHT/BLU
GRY/RED
Range TCM terminal
GearB20
(High clutch
pressure SW)B1
(2-4 brake pressure
SW)B12 (Low & reverse
brake pressure SW)P - More than 10V More than 10V More than 10VR Reverse More than 10V More than 10V -N - More than 10V More than 10V More than 10VD, 3, 2 1st More than 10V More than 10V More than 10V2nd More than 10V - More than 10V3rd - More than 10V More than 10V4th - - More than 10VL 1st More than 10V More than 10V -2nd More than 10V - More than 10V3rd - More than 10V More than 10V4th - - More than 10V
Range TCM terminal
GearB8
(High clutch
solenoid)B9
(Low clutch
solenoid)B7
(2 -4 b rake
solenoid)B6
(Lo w & reve rs e
brake solenoid)P - Approx. 6.8V
(AC range)- Approx. 6.8V
(AC range)Approx. 6.2V
(AC ra ng e)
R Reverse Approx. 6.8V
(AC range)- Approx. 6.8V
(AC range)-
N - Approx. 6.8V
(AC range)- Approx. 6.8V
(AC range)Approx. 6.8V
(AC ra ng e)
D, 3, 2 1st Approx. 6.8V
(AC range)- Approx. 6.8V
(AC range)Approx. 6.8V
(AC ra ng e)
2nd Approx. 6.8V
(AC range)- - Approx. 6.8V
(AC ra ng e)
3rd - - Approx. 6.8V
(AC range)Approx. 6.8V
(AC ra ng e)
4th - Approx. 6.8V
(AC range)- Approx. 6.8V
(AC ra ng e)
L 1st Approx. 6.8V
(AC range)- Approx. 6.8V
(AC range)-
2nd Approx. 6.8V
(AC range)- - Approx. 6.8V
(AC ra ng e)
3rd - - Approx. 6.8V
(AC range)Approx. 6.8V
(AC ra ng e)
4th - Approx. 6.8V
(AC range)- Approx. 6.8V
(AC ra ng e)
Go to Step 6
In case of fault in
the machine
system, repair that
portion or replace
the unit.
Slip of clutch or fault
of control valve.

7A2-120 DIAGNOSIS (JR405E)
No. D2: Gear is Shifted Frequently

Description:

Gear is shifted down immediately though the accelerator pedal is stepped on a little in D, 3, 2, or L range.

Diagnosis Hints:

Basically, the same cause as "No. D1: Faulty gear shifting" is considered. However, as possible cause, fault
input signal of throttle position sensor or speed sensor, fault input signal of inhibitor switch, or fault of TCM
power source, earth, ground return wire are considered first.

Then, slip of the clutch, fault of the control valve are considered.





No. D3: Gear Shift Point is Low or High at All Point
No. D4: Gear Shift Point is Low or High at Limited Point

Description:

Gear shift point is deviated from the shift diagram.

Gear is not shifted up properly though the vehicle is accelerated.

Gear is not shifted immediately and enough acceleration cannot be obtained though the accelerator pedal is
stepped on.

Diagnosis Hints:

If the cause is not faulty gear shift, throttle position sensor disordered or fault input of speed sensor is
considered. Output signal of the throttle position sensor is changed to linear one.
(Refer the paragraph about the faulty throttle position sensor of "No. D1: Faulty gear shifting".)





No. D5: No Kick-down

Description:

The engine speeds up but vehicle speed does not increase when the accelerator pedal is stepped on at the
starting.

Diagnosis Hints:

When the gear shift is normal only without kick-down, possibility of fault of the throttle position sensor. Check
that the throttle voltage increases linearly in proportion to the throttle opening.
(Refer the paragraph about the faulty throttle position sensor of "No. D1: Faulty gear shifting".)

DIAGNOSIS (JR405E) 7A2-121
No. E1: No Gear Shift

Description:

Range is fixed without shifting the gear of 1st to 2nd, 2nd to 3rd, and 3rd to 4th.

Gear may be shifted or may not be shifted.

Diagnosis Hints:

Fixing at some gear speed, signal error from throttle position sensor or trouble in the AT main unit are supposed.

Possible Cause:

Slip of clutch (low clutch, high clutch and 2-4 brake).
If slip of clutch is caused, a DTC (gear ratio error) is stored.

Dropped line pressure.

Fixing at 3rd position (fail-safe activated).
Since the gear is fixed at the 3rd position because of the fail-safe function, a trouble that "No gear shift"
is resulted. In this case, the DTC is memorized.
When TCM stops operation because of faulty TCM ground, the gear is fixed at the 3rd position because
of a mechanical reason. In this case, no DTC is memorized.





Incorrect properties of throttle opening signal (serial communication) of throttle position sensor.
Throttle opening signal (serial communication) of the throttle position sensor does not change in
proportion to the throttle opening. In this case, fixing at the high or low gear results in such a trouble
that "No Gear Shift".

Trouble in control valve body (faulty operation, sticking, clogged oil passage)

Step Action Yes No
1 Gear ratio trouble diagnosis.
Travel in the following sequence for about 7 seconds or more in
each range: Start in the L range (1st) to 2 range (2nd) to 3 range
(3rd) to D range (4th) (to detect the gear ratio trouble exactly, this
process should be carried out).
Go to Step 2 Go to Step 2
2 Are any DTCs stored?
Go to DTC Chart Go to Step 3
3 Are the quantity, contamination and smell normal?
If the ATF level is
low, replenish up to
the specified level.

Go to Step 4
If ATF is extremely
black and
contaminated and
smells burnt, slip of
the clutch is
supposed.
Overhaul the AT
unit.

7A2-124 DIAGNOSIS (JR405E)
No. E2: Only 4th gear (O/D) is Not Selectable

Description:

Gear is not shifted up from 3rd to 4th though the vehicle is accelerated.

Possible Cause:

Disordered select cable.

Disordered inhibitor switch.

ATF thermo sensor detects low oil temperature (4th gear is prohibited temperature less than 10C.).

Clogged oil passage of low clutch duty solenoid.

Trouble in control valve body (faulty operation, sticking, clogged oil passage).

Step Action Yes No
1 Dislocation or disordered of select lever.
Does the vehicle move when the brake is released in a position
other than the P range and the vehicle is pushed?
Go to Step 2
Adjust the select
cable.
2 Gear ratio trouble diagnosis.
Travel in the following sequence for about 7 seconds or more in
each range: Start in the L range (1st) to 2 range (2nd) to 3 range
(3rd) to D range (4th) (to detect the gear ratio trouble exactly, this
process should be carried out)
Go to Step 3 Go to Step 3
3 Are any DTCs stored?
Go to DTC Chart Go to Step 4
4 Are the quantity, contamination and smell normal?
If the ATF level is
low, replenish up to
the specified level.

Go to Step 5
If ATF is extremely
black and
contaminated and
smells burnt, slip of
the clutch is
supposed.
Overhaul the AT
unit.

DIAGNOSIS (JR405E) 7A2-127
No. F1: Low Maximum Speed or Poor Acceleration

Description:

Starting acceleration is poor.

Acceleration is slow though the accelerator pedal is stepped on during the running.

Diagnosis Hints:

In addition to the low engine output, faulty gear shifting of AT or fixing at the 3rd position may be possible.
Therefore, in case of such a trouble that "maximum speed is low, and acceleration is poor", it should be cleared
up whether the trouble is originated from the engine system of AT system by a running test, inspection of stall
revolution, etc.

Possible Cause:

Clogged air cleaner, out of injection timing, dropped compression pressure, etc.

Fixing at 3rd position (fail-safe activated).
Since the gear is fixed at the 3rd position because of the fail-safe function, a trouble that "Maximum
speed is low, and acceleration is poor" is resulted. In this case, the DTC is memorized.
When TCM stops operation because of faulty TCM ground, the gear is fixed at the 3rd position because
of a mechanical reason. In this case, no DTC is memorized.

Disordered inhibitor switch .

Incorrect properties of throttle opening signal (serial communication) of throttle position sensor.
Throttle opening signal (serial communication) of the throttle position sensor does not change in
proportion to the throttle opening. In this case, fixing at the high or low gear results in such a trouble
that "Maximum Speed is Low and Acceleration is Poor".

Slip of clutch (low clutch, high clutch).

If slip of clutch is caused, a DTC (gear ratio error) is stored.

Dropped line pressure.

Trouble in the torque converter system (faulty operation).

Step Action Yes No
1 Test Drive.
Is the gear smoothly shifted in the order of 1st to 2nd, 2nd to 3rd,
3rd to 4th gear and lock up?
Clogged air
cleaner, out of
injection timing,
dropped
compression
pressure, etc. Go to Step 2
2 Gear ratio trouble diagnosis.
Travel in the following sequence for about 7 seconds or more in
each range: Start in the L range (1st) to 2 range (2nd) to 3 range
(3rd) to D range (4th) (to detect the gear ratio trouble exactly, this
process should be carried out)
Go to Step 3 Go to Step 3
3 Are any DTCs stored?
Go to DTC Chart Go to Step 4