2004 ISUZU TF SERIES Throttle Position Sensor

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 proportion to the throttle opening output?



TPSTCM
A16
C56
(28)C94
(16) RED/ WHT
C56
(49)
(38)
(57)
(69)ECM
A47 (GND)
A35 (Out put )
A26
A55 (+5V)
A69 (I dl e SW)
Go to Step 7
Repair the defect or
replace.
8 Check of power supply to and earth of TCM.
Are the power supply and earth proper?



TCM
A1 (+B)
B5
B15
H23
(15)C95
(5)
(15) BLK/YEL
BLK BLK Battery
C94
(1)
BLK
Go to Step 9
Check the power
source harness and
earth harness (bolt
tightening to the
body).
9 Is the stall revolution correct in D, 3, 2 and L range? Refer the
STALL TEST section in this manual.
Go to Step 10
Repair the defect or
replace.
10 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) 7A2-115
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.

7A2-118 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 sensor using a Tech 2 or circuit tester.

Inhibitor SW

TCM
A2 (P)
A17 (3)
B2 (2)
B10 (N)
B11 (D)
B19 (R)
B21 (L)
C95
(2 )
(10)
(11 )
(19)
(21) Y E L /V IO
RED/BLK
BLUBLK/GRN
Starter Relay
C94
(2 )
(3 )
BH22
(1)
(6)
(4)
(7)
(5)
(2) P
2
R
N
D
3
L
Start SW
PNK/BLU
E51
(2)
(4)
(8)
(5)
(1)
(9)
(6)
(3)
(10)
(7)
(38)
(15)
(3)
(37)
H4PNK/BLK
RED/YEL Y E L /V IO
BLK/GRN
PNK/BLK RED/BLK
BLU RED/YEL
PNK/BLU
BLK/WHT
BLK
BLK BLK/WHT Key Switch WHT
WHT
ICU (W/ Immobilis e r)
Ground (W/O Immobilis e r)
TCM terminal
RangeA2 B19 B10 B11 B17 B2 B21
P10 –
14.5V-- - - - -
R-10 –
14.5V-- ---
N--10 –
14.5V----
D - - - 10 –
14.5V---
3----10 –
14.5V--
2-----10 –
14.5V-
L------10 –
14.5V
Go to Step 7
Adjust the inhibitor
switch.
7 Is a voltage value in proportion to the throttle opening output?




TPSTCM
A16
C56
(28)C94
(16) RED/ WHT
C56
(49)
(38)
(57)
(69)ECM
A47 (GND)
A35 (Out put )
A26
A55 (+5V)
A69 (I dl e SW)
Go to Step 8
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) 7A2-121
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.

7A2-122 DIAGNOSIS (JR405E)
Step Action Yes No
4 Inspection of inhibitor switch using a Tech 2 or circuit tester.
When the select lever is operated, is the data display in the Tech
2 correct or voltage at each range correct?
Inhibitor SW

TCM
A2 (P)
A17 (3)
B2 (2)
B10 (N)
B11 (D)
B19 (R)
B21 (L)
C95
(2 )
(10)
(11 )
(19)
(21) Y E L /V IO
RED/BLK
BLUBLK/GRN
Starter Relay
C94
(2 )
(3 )
BH22
(1)
(6)
(4)
(7)
(5)
(2) P
2
R
N
D
3
L
Start SW
PNK/BLU
E51
(2)
(4)
(8)
(5)
(1)
(9)
(6)
(3)
(10)
(7)
(38)
(15)
(3)
(37)
H4PNK/BLK
RED/YEL Y E L /V IO
BLK/GRN
PNK/BLK RED/BLK
BLU RED/YEL
PNK/BLU
BLK/WHT
BLK
BLK BLK/WHT Key Switch WHT
WHT
ICU (W/ Immobilis e r)
Ground (W/O Immobilis e r)
TCM terminal
RangeA2 B19 B10 B11 B17 B2 B21
P10 –
14.5V-- - - - -
R-10 –
14.5V-- ---
N--10 –
14.5V----
D - - - 10 –
14.5V---
3----10 –
14.5V--
2-----10 –
14.5V-
L------10 –
14.5V
Go to Step 5
Adjust the inhibitor
switch.
5 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 proportion to the throttle opening output?



TPSTCM
A16
C56
(28)C94
(16) RED/ WHT
C56
(49)
(38)
(57)
(69)ECM
A47 (GND)
A35 (Out put )
A26
A55 (+5V)
A69 (I dl e SW)
Go to Step 6
Repair the defect or
replace.

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

DIAGNOSIS (JR405E) 7A2-129
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 proportion to the throttle opening output?




TPSTCM
A16
C56
(28)C94
(16) RED/ WHT
C56
(49)
(38)
(57)
(69)ECM
A47 (GND)
A35 (Out put )
A26
A55 (+5V)
A69 (I dl e SW)
Go to Step 7
Repair the defect or
replace.
7 Check of power supply to and earth of TCM.
Are the power supply and earth proper?




TCM
A1 (+B)
B5
B15
H23
(15)C95
(5)
(15) BLK/YEL
BLK BLK Battery
C94
(1)
BLK
Go to Step 8
Check the power
source harness and
earth harness (bolt
tightening to the
body).
8 Is the stall revolution correct in D, 3, 2 and L range? Refer the
STALL TEST section in this manual.
Go to Step 6
Repair the defect or
replace.
9 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.