2004 ISUZU TF SERIES Workshop Manual

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Page 4105 of 4264

ISUZU TF SERIES 2004 Workshop Manual DIAGNOSIS (JR405E) 7A2-113
Step Action Yes No
6 Inspect the output voltage and throttle opening signal of the
throttle position sensor using a Tech 2 or circuit tester.
Is a voltage value in propo

Page 4106 of 4264

ISUZU TF SERIES 2004 Workshop Manual 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 G

Page 4107 of 4264

ISUZU TF SERIES 2004 Workshop Manual 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:

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 4108 of 4264

ISUZU TF SERIES 2004 Workshop Manual 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.

Page 4109 of 4264

ISUZU TF SERIES 2004 Workshop Manual 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?

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.

Page 4110 of 4264

ISUZU TF SERIES 2004 Workshop Manual 7A2-118 DIAGNOSIS (JR405E)
Step Action Yes No
6 Inspection of inhibitor switch using a Tech 2 or circuit tester.
Inspect the output voltage and throttle opening signal of the
throttle position sen

Page 4111 of 4264

ISUZU TF SERIES 2004 Workshop Manual DIAGNOSIS (JR405E) 7A2-119
Step Action Yes No
8 Inspect the output signal of the speed sensor using a Tech 2 or
circuit tester.
Is the data display in the Tech 2 correct or output voltage correct

Page 4112 of 4264

ISUZU TF SERIES 2004 Workshop Manual 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.

Diag

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