2004 ISUZU TF SERIES engine
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7A2-106 DIAGNOSIS (JR405E)
No. B6: Engine Starter Does Not Run in P or N Range
No. B7: Engine Starter Runs Except in P or N Range
Description:
The engine starter does not run though the P or N range is selected.
The engine starter runs though the R or D, 3, 2or L range is selected.
Possible Cause:
Disordered select cable.
Disordered Inhibitor switch, disconnection or short-circuit of inhibitor switch.
No. B8: Extended Time Lag When Shift Lever is Changed to N to D
Description:
The shift time lag is longer than standard value when shift lever is changed to N to D.
Possible Cause:
Forward range line pressure is low.
Slip of low & reverse clutch.
Slip of low one-way clutch.
Trouble in control valve body (faulty operation, sticking, clogged oil passage).
Faulty low clutch duty solenoid operation.
Shortage or faulty quality of ATF.
No. B9: Extended Time Lag When Shift Lever is Changed to N to R
Description:
The shift time lag is longer than standard value when shift lever is changed to N to R.
Possible Cause:
Reverse range line pressure is low.
Slip of low & reverse brake.
Slip of reverse clutch.
Trouble in control valve body (faulty operation, sticking, clogged oil passage).
Faulty low & reverse brake duty solenoid operation.
Shortage or faulty quality of ATF.
Page 4100 of 4264
7A2-108 DIAGNOSIS (JR405E)
No. C1: Engine Race Up (Slip) When Gear is Shifted Up to 1st to
2nd
No. C2: Engine Race Up (Slip) When Gear is Shifted Up to 2nd to
3rd
No. C3: Engine Race Up (slip) When Gear is Shifted Up to 3rd to
4th
No. C4: Engine Race Up (Slip) When Gear is Shift Down or Kick-
down to 4th to 3rd
No. C5: Engine Race Up (Slip) When Gear is Shift Down or Kick-
down to 4th to 2nd
No. C6: Engine Race Up (Slip) When Gear is Shift Down or Kick-
down to 3rd to 2nd
No. C7: Engine Race Up (Slip) When Gear is Shift Down or Kick-
down to 4th or 3rd to 1st
No. C8: Engine Race Up (Slip) Others
Description:
The engine speed up when the accelerator pedal is stepped on for acceleration and the gear is shifted up.
The engine speed up when the accelerator pedal is stepped on for acceleration and the gear is shifted down or
for kick-down during steady run.
The engine speed up when the accelerator pedal is stepped on for acceleration and the gear is shifted down or
for kick-down during steady run.
Diagnosis Hints:
Possibility of slip of clutch is supposed. If slip of clutch has occurred, a DTC of "Gear ratio error" is stored.
Possible Cause:
Slip of clutch.
If slip of clutch is caused, a DTC (gear ratio error) is stored.
Dropped line pressure.
Trouble in control valve body (faulty operation, sticking, clogged oil passage).
Page 4101 of 4264
DIAGNOSIS (JR405E) 7A2-109
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
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 SWH22
(8)
Range TCM terminal
GearB20
(High clutch
pressure SW)B1
(2-4 brake pressure
SW)B12 (Low & reverse
brake pressu re 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
Go to Step 6
Repair the defect or
replace.
Page 4104 of 4264
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.
Page 4106 of 4264
7A2-114 DIAGNOSIS (JR405E)
No. C12: Large Shock When Gear is Shifted to 1st to 2nd or 2nd
to 1st
No. C13: Large Shock When Gear is Shifted to 2nd to 3rd or 3rd to
2nd
No. C14: Large Shock When Gear is Shifted to 3rd to 4th or 4th to
3rd
No. C15: Large Shock When Kick-down
No. C16: Large Shock When No Acceleration
No. C17: Large Shock When Gear is Shifted Down to 2nd to 1st in
L Range
No. C18: Large Shock (Other)
No. C19: Large Shock When Vehicle Speed is Downed by No
Accelerator Pedal or Vehicle is Stopped
Description:
Large shock is felt when the accelerator pedal is stepped on for acceleration and the gear is shifted up or down.
Large shock is felt when the accelerator pedal is stepped on for kick-down.
Large shock is felt when the accelerator pedal is not stepped on.
Large shock is felt when the shift lever is selected in L range.
Diagnosis Hints:
Basically same causes as "No. C1 - C8: Engine races up (slip)" are considered.
No. C20: Large lock-up shock
Description:
Large shock is felt at lock-up.
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".
No. C21: Shift Down or Engine Over-run When The Accelerator
Pedal is Stepped on in 4th Gear
Description:
Shift down or engine over-run above the kick-down area.
Diagnosis Hints:
Basically same causes as "No. C1 - C8: Engine races up (slip)" are considered.
Page 4107 of 4264
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.
Page 4112 of 4264
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".)
Page 4119 of 4264
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