check engine ISUZU TF SERIES 2004 Workshop Manual

DIAGNOSIS (JR405E) 7A2-77
Step Action Yes No
6 Is the quantity of ATF correct?
Go to Step 7
Correct the quantity of
ATF.
Go to Step 9
7 Connect the Tech 2 and test the solenoids of respective
solenoids for low & reverse brake, 2-4 brake, high clutch and
low clutch. Is operation sound heard from each solenoid?
Go to Step 8
Replace the solenoid
that does not generate
the operation sound.
Go to Step 9
8 Check the line pressure during the idling and at the engine stall
speed. Is the line pressure correct?
Go to Step 10
Either control valve, oil
pump or power train
parts (clutch, brake)
will be faulty. Replace
or overhaul the
transmission unit.
Go to step 10
9 Run the vehicle, and is the gear shifted from 1st to 4th
correctly?
Go to Step 10
Either control valve, oil
pump or power train
parts (clutch, brake)
will be faulty. Replace
or overhaul the
transmission unit.
Go to step 10
10 Clear the DTC from the memory and perform the work after
repair. Is the same DTC code outputted again in the
subsequent DTC check?
Replace the TCM Go to Step 11
11 Are the other DTCs outputted?
Go to Other DTC
Section Action is completed

DIAGNOSIS (JR405E) 7A2-79

Step Action Yes No
1 Turn the key switch on and check the DTC. Is only the DTC for
low & reverse brake fail-safe valve failure outputted?
Go to Step 2
Go to Other DTC
Section
2 Clear the DTC from the memory. Turn the key switch off once,
and then start the engine. Does the CHECK TRANS blink
when the D range is selected and about 10 seconds elapsed?
Go to Other DTC
Section Go to Step 3
3 Run the vehicle, shift the gear from 1st to 4th, stop the vehicle,
and again shift the gear from 1st to 4th. Does the CHECK
TRANS blink at this time?
Go to Step 4
The low & reverse
brake fail-safe valve
may be faulty
temporarily.
Go to step 5
4 Turn the key switch on and check the DTC. Is only the DTC for
the low & reverse brake fail-safe valve failure outputted?
Repair or replace the
control valve.
Go to Step 5
Go to Other DTC
Section
5 Clear the DTC from the memory and perform the work after
repair. Is the same DTC code outputted again in the
subsequent DTC check?
Replace the TCM Go to Step 6
6 Are the other DTCs outputted?
Go to Other DTC
Section Action is completed

DIAGNOSIS (JR405E) 7A2-81

Step Action Yes No
1 Turn the key switch on and check the DTC. Is only the DTC for
2-4 brake fail-safe valve failure outputted?
Go to Step 2
Go to Other DTC
Section
2 Clear the DTC from the memory. Turn the key switch off once,
and then start the engine. Does the CHECK TRANS blink when
the D range is selected and about 10 seconds elapsed?
Go to Other DTC
Section Go to Step 3
3 Run the vehicle, shift the gear from 1st to 4th, stop the vehicle,
and again shift the gear from 1st to 4th. Does the CHECK
TRANS blink at this time?
Go to Step 4
The 2-4 brake fail-safe
valve may be faulty
temporarily.
Go to step 5
4 Turn the key switch on and check the DTC. Is only the DTC for
the 2-4 brake fail-safe valve failure outputted?
Repair or replace the
control valve.
Go to Step 5
Go to Other DTC
Section
5 Clear the DTC from the memory and perform the work after
repair. Is the same DTC code outputted again in the
subsequent DTC check?
Replace the TCM Go to Step 6
6 Are the other DTCs outputted?
Go to Other DTC
Section Action is completed

DIAGNOSIS (JR405E) 7A2-93
No. A1: Vehicle Does Not Run in D, 3, 2, L and R Range

Description:

Vehicle does not run though the accelerator pedal is stepped on.

Diagnosis Hints:

Some trouble in the AT main unit is supposed (since the vehicle can run even if the TCM is defective). However,
since the trouble of the main unit may be originated from the sensor system or output system, these systems
should be also checked to prevent reproduce of the trouble.

Possible Cause:

Slip of clutch (low clutch, low one-way clutch, reverse clutch, low & reverse brake).
If slip of clutch is caused, a DTC (gear ratio error) is stored.

Shortage or faulty quality of ATF.

Dropped line pressure.

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

Disordered select cable (select indicator light indicates D, 3, 2, L or R but the hydraulic system is not in the D, 3,
2, L, or R range).

Faulty torque generated.

Trouble in the torque converter (faulty operation, sticking), insufficient engine output.

Malfunction of parking mechanism.

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 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 Is the stall revolution correct in all range? Refer the STALL
TEST section in this manual.
Go to Step 5
Repair the defect or
replace.
5 Is the line pressure correct? Refer the LINE PRESSURE
TEST section in this manual. Trouble in the AT
assembly or control
valve.
Repair the defect or
replace.

7A2-94 DIAGNOSIS (JR405E)
No. A2: Vehicle Does Not Run in R Range

Description:

Vehicle does not run in R range only.

It runs correctly in D, 3, 2, and L ranges.

Diagnosis Hints:

Some trouble in the AT main unit is supposed (since the vehicle can run even if the TCM is defective). However,
since the trouble of the main unit may be originated from the sensor system or output system, these systems
should be also checked to prevent reproduce of the trouble.

Possible Cause:

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

Shortage or faulty quality of ATF.

Dropped line pressure.

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

Disordered select cable (select indicator light indicates R but the hydraulic system is not in the R range).

Faulty torque generated.

Trouble in the torque converter (faulty operation, sticking), insufficient engine output.

Malfunction of parking mechanism.

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 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 Is the stall revolution correct in R range? Refer the STALL
TEST section in this manual.
Go to Step 5
Repair the defect or
replace.
5 Is the line pressure correct? Refer the LINE PRESSURE
TEST section in this manual. Trouble in the AT
assembly or control
valve.
Repair the defect or
replace.

DIAGNOSIS (JR405E) 7A2-95
No. A3: Vehicle Does Not Run in D, 3, 2 and L Range

Description:

Vehicle does not run in D, 3, 2 and L range only.

It runs correctly in R ranges.

Diagnosis Hints:

Some trouble in the AT main unit is supposed (since the vehicle can run even if the TCM is defective). However,
since the trouble of the main unit may be originated from the sensor system or output system, these systems
should be also checked to prevent reproduce of the trouble.

Possible Cause:

Slip of clutch (low clutch and low one-way clutch).
If slip of clutch is caused, a DTC (gear ratio error) is stored.

Shortage or faulty quality of ATF.

Dropped line pressure.

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

Disordered select cable (select indicator light indicates D, 3, 2 and L but the hydraulic system is not in the D, 3, 2
and L range).

Faulty torque generated.

Trouble in the torque converter (faulty operation, sticking), insufficient engine output.

Malfunction of parking mechanism.

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 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 Is the stall revolution correct in D, 3, 2 and L range? Refer
the STALL TEST section in this manual.
Go to Step 5
Repair the defect or
replace.
5 Is the line pressure correct? Refer the LINE PRESSURE
TEST section in this manual. Trouble in the AT
assembly or control
valve.
Repair the defect or
replace.

DIAGNOSIS (JR405E) 7A2-103
No. B4: Large Shock When Shift Lever is Changed to N to D
Range or N to R Range

Description:

Large shock is felt when selecting D or R range from N range during the idling after warming up.

Diagnosis Hints:

Check the entire condition of the vehicle for unusual other than AT including faulty engine mount, exhaust
hanger, etc.

When the fail-safe operation, select shock may grow worse. In such a case, check for the DTC. If no DTC is
issued, shock due to faulty operation of the control valve or burnt clutch is considered.

Possible Cause:

High engine idling.

Dislocated select lever, improper inhibitor switch adjusting point.

Faulty or insufficient tightening of engine mount, exhaust mount.

Play of suspension.

Burnt clutch.

Too low or high line pressure.

Faulty input signal system.

Faulty control valve. (faulty operation or sticking of accumulator)

7A2-104 DIAGNOSIS (JR405E)
No. B5: Engine Stalls When Selecting From N Range to
R, D, 3, 2 or L Range

Description:

The engine stalls when selecting from N or P range to a run range during the engine idling.

Diagnosis Hints:

As causes attributable to the engine, faulty idle up, insufficient engine output, etc. are considered.

As a cause of the AT system, faulty lockup piston system (lockup engine stall) is considered.

If the oil through resistance increases remarkably due to clogged oil cooler or some other reason, or if the ATF
level decreases, the lock-up piston works causing the engine stall.

Possible Cause:

Disordered idling speed, faulty idle up, faulty engine output, shortage output.

Insufficient ATF quantity (dropped level).

Clogged oil cooler (foreign substance mixed in).

Faulty lock-up piston (clogged oil passage of solenoid drive circuit, faulty operation).

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 Check of engine idle up speed
Does the idle speed increase when the air conditioning or other
electric load is turned on?
Go to Step 5
Repair the defect or
replace.

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) 7A2-133
No. G4: Large Noise During Idling with the Vehicle in Stop State

Description:

The transmission is noisy during the idling speed in all ranges.

Diagnosis Hints:

Causes such as solenoid operating sound or faulty oil pump are considered.

Distinguishing to some extent is possible by stopping the solenoid operation temporarily, checking the correlation
for the former case and, changing the line pressure and confirming the correlation with noise.

As a matter of course, noise may be generated around the engine, for instance, other than the AT and should be
checked carefully.
Note:
When the noise is generated only at the time of gear shift, it may be the sound of flowing ATF or gear
noise. If the sound varies depending on the gear speed to be shifted, it may be the gear noise generated
from the planetary gear and its related components. If the sound varies depending on the vehicle
speed, it may be the gear noise of the output system, and if varying depending on the engine speed, it
may be the gear noise of the input system or faulty torque converter.
In either case, sound may be "noise" depending on the origin and resonance object. When the object
generating the sound (resonance object) and the sound source (vibration source) are different,
investigation of the cause may be difficult.





No. H1: Judder Occurs at the Lock-up

Diagnosis Hints:

The vehicle body judders at lock-up.

Diagnosis Hints:

Slip due to burning of the lockup piston or insufficient fastening due to dropped working pressure are considered.
Trouble diagnosis flow is basically the same as "No. I1: No lock-up".
Note:
When the lock-up piston has burnt, foreign material mixed in the oil cooler is considered. In such a
case, inspect the oil cooler circuit for clogging of the oil cooler.





No. H2: Large Lock-up Shock
No. H3: Lock-up Point is High or Low

Description:

Large shock is felt at lock-up.

Lock-up point is excessive high or low.

Diagnosis Hints:

Out of properties of input sensor or faulty lock-up piston pressure system are considered.

Trouble diagnosis flow is basically the same as "No. I1: No lock-up".