brake ISUZU TF SERIES 2004 Workshop Manual

DIAGNOSIS (JR405E) 7A2-57
DTC P0768 (Flash Code 34) Low Clutch Duty Solenoid Failure



C ontrol Valve

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

Term inal
Assembly
BLK/YEL
RED
2-4 Brake Solenoid

High Clutch Solenoid

Low Clutch Solenoid

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

7A2-58 DIAGNOSIS (JR405E)
Gear Position & Shift Solenoid Operation


Range TCM terminal

Gear B8
(High clutch
solenoid) B9
(Low clutch
solenoid) B7
(2-4 brake
solenoid) B6
(Low & reverse
brake solenoid)
P 

R Reverse


N 

D, 3, 2 1st

2nd


3rd


4th


L 1st


2nd


3rd


4th


: On (Operated)

: Off (Not operated)

Setting Condition:

The low clutch duty solenoid signal is open circuit or short circuit.
(The voltage different from the output ON/OFF signals was detected while the TCM monitors the solenoid output
voltage.)

Fail Safe:

When the vehicle is running, the operation of the low clutch duty solenoid and the lock-up solenoid is stopped
(OFF), the gear position selected at the trouble detection is held, and the lock-up is inhibited.

After the vehicle stopped, all solenoid operations stop (OFF) and the gear is fixed to the 3rd.

Possible Cause:

Low clutch duty solenoid malfunction.

Open (Off) circuit or short (On) circuit harness of the low clutch duty solenoid.

Open circuit, short circuit to battery or short circuit to ground between low clutch duty solenoid terminal 3 and
TCM terminal B9 (C95).

Insufficient ground condition of the low clutch duty solenoid.

Poor connection of each connector.

7A2 -64 DIAGNOSIS (JR405E)
DTC P1853 (Flash Code 26) Low & Reverse Brake Pressure Switch Failure



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)



Pre-setting Condition:

No gear shifting.

No Check Trans indicator lamp.

No system voltage failure.

No inhibitor switch failure.

Low & reverse brake duty solenoid 0 or 100 %.

ATF temperature more than 60 C.

ATF input voltage more than 0.1V.

Engine speed more than 500 rpm.

DIAGNOSIS (JR405E) 7A2-65

Setting Condition:

During the running, the low & reverse brake pressure switch does not turn on though hydraulic pressure is
supposed to be generated in the low & reverse brake.
(All pre-setting conditions are met for 2.5 seconds, Low & reverse brake duty solenoid 0% and low & reverse
brake pressure switch off in R range)
Or

During the running, the low & reverse brake switch does not turn off though no hydraulic pressure is supposed to
be generated in the low & reverse brake.
(All pre-setting conditions are met for 2.5 seconds, 4th gear, all pressure switch on and gear ratio 0.652 - 0.735
in D range.)

Fail Safe:

No fail safe function

Possible Cause:

Low & reverse brake duty solenoid malfunction.

Low & reverse brake pressure switch wire open circuit or short circuit.

Open circuit, short circuit to battery or short circuit to ground between low & reverse brake pressure switch
terminal 12 and TCM terminal B12 (C95).

Low & reverse brake hydraulic circuit malfunction in the control valve.

Poor connection of each connector.

Reference:
When the low & reverse brake pressure switch is operated, following signal is outputted.
Measurement terminal: B12 (C95) and B22 (C95)
-At other than R rage or L range in 1st gear: More than 10V
-At R range or L range in 1 st gear: Less than 1V

7A2-66 DIAGNOSIS (JR405E)
Step Action Yes No
1 Clear the DTC from the memory once.
Was the action complete?


Go to Step 2
Refer DTC clear
method in this
manual.
2 Turn the ignition switch off once, then restart the engine and shift to
4th gear in the D range. When about 10 seconds elapsed, does the
CHECK TRANS lamp blink?
Go to Step 3 Go to Step 7
3 Is the DTC P0753 (31) Low & Reverse Brake Duty Solenoid Failure
stored? Go to P0753 (31)
Section Go to Step 4
4 Connect the Tech 2 and select the item for low & reverse brake
pressure switch. Is the indication of low & reverse brake pressure
switch turned off when the terminal assembly connector is
disconnected?
Go to Step 5
Repair the harness
or connector.
Go to Step 12
5 Turn the key switch off and disconnect the terminal assembly
connector. Are the pins correct?
Go to Step 6
Repair the
connector or pin.
Go to Step 12
6 Remove the oil pan. Is the continuity correct between terminal
assembly terminal 12 and low & reverse brake pressure switch
connector?

12

Repair the harness
or connector.
Go to Step 12
Replace pressure
switch.
Go to Step 12
7 Start the engine and select the R range. When about 10 seconds
elapsed, does the CHECK TRANS lamp blink?
Go to Step 8
Go to P0753 (31)
Section
8 Connect the Tech 2, and with the key switch in OFF position, short
the terminals 11 and 12 on the vehicle harness side. Does the
indication of the low & reverse brake pressure switch on the Tech 2
becomes on when the key switch is turned on?
Go to Step 9
Repair the harness
or connector.
Go to Step 12

DIAGNOSIS (JR405E) 7A2-67
Step Action Yes No
9 Check if the trouble is caused by a poor connection of terminal
assembly connector.
With the key switch in OFF position, is the connection condition of
the connector and harness correct?
Go to Step 10
Repair the harness
or connector.
Go to Step 12
10 Remove the oil pan. Is the continuity correct between terminal
assembly terminal 12 and low & reverse brake pressure switch
connector?

12
Go to Step 11
Repair the harness
or connector.
Go to Step 12
11 Is the result OK when the oil pan is removed and the low & reverse
brake pressure switch is checked? Refer the ON VEHICLE
SERVICE SECTION in this manual for the procedure. Repair the control
valve.
Go to Step 12
Replace pressure
switch.
Go to Step 12
12 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 13
13 Are the other DTCs outputted? Go to Other DTC
Section Action is completed

7A2-68 DIAGNOSIS (JR405E)
DTC P1858 (Flash Code 27) 2-4 Brake Pressure Switch Failure



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)




Pre-setting Condition:

No gear shifting.

No Check Trans indicator lamp.

No system voltage failure.

No inhibitor switch failure.

2-4 brake duty solenoid 0 or 100 %.

ATF temperature more than 60 C.

ATF input voltage more than 0.1V.

Engine speed more than 500 rpm.

DIAGNOSIS (JR405E) 7A2-69

Setting Condition:

During the running, the 2-4 brake pressure switch does not turn on though hydraulic pressure is supposed to be
generated in 2-4 brake.
(All pre-setting conditions are met for 2.5 seconds, 2-4 brake pressure switch off, high clutch pressure switch on
and gear ratio more than 0.65 or less than 0.74 with 4th gear in D range.)
Or

During the running, the 2-4 brake switch does not turn off though no hydraulic pressure is supposed to be
generated in the 2-4 brake.
(All pre-setting conditions are met for 2.5 seconds, 2-4 brake pressure switch on in D or N range.)

Fail Safe:

No fail safe function

Possible Cause:

2-4 brake duty solenoid malfunction.

2-4 brake pressure switch wire open circuit or short circuit.

Open circuit, short circuit to battery or short circuit to ground between 2-4 brake pressure switch terminal 7 and
TCM terminal B1 (C95).

2-4 brake hydraulic circuit malfunction in the control valve.

Poor connection of each connector.

Reference:
When the 2-4 brake pressure switch is operated, following signal is outputted.
Measurement terminal: B1 (C95) and B22 (C95)
-At other than 2nd or 4th gear: More than 10V
-At 2nd or 4th gear: Less than 1V

7A2-70 DIAGNOSIS (JR405E)
Step Action Yes No
1 Clear the DTC from the memory once.
Was the action complete?
Go to Step 2
Refer DTC clear
method in this
manual.
2 Turn the ignition switch off once, then restart the engine and in D
range. When about 10 seconds elapsed, does the CHECK TRANS
lamp blink?
Go to Step 3 Go to Step 7
3 Is the DTC P0758 (32) 2-4 Brake Duty Solenoid Failure stored?
Go to P0758 (32)
Section Go to Step 4
4 Connect the Tech 2 and select the item for 2-4 brake pressure
switch. Is the indication of 2-4 brake pressure switch turned off when
the terminal assembly connector is disconnected?
Go to Step 5
Repair the harness
or connector.
Go to Step 12
5 Turn the key switch off and disconnect the terminal assembly
connector. Are the pins correct?
Go to Step 6
Repair the
connector or pin.
Go to Step 12
6 Remove the oil pan. Is the continuity correct between terminal
assembly terminal 7 and 2-4 brake pressure switch connector?

7

Repair the harness
or connector.
Go to Step 12
Replace pressure
switch.
Go to Step 12
7 Start the engine and shift to 4th gear in the D range. When about 10
seconds elapsed, does the CHECK TRANS lamp blink?
Go to Step 8
Go to P0758 (32)
Section
8 Connect the Tech 2, and with the key switch in OFF position, short
the terminals 11 and 7 on the vehicle harness side. Does the
indication of the 2-4 brake pressure switch on the Tech 2 becomes
on when the key switch is turned on?
Go to Step 9
Repair the harness
or connector.
Go to Step 12

DIAGNOSIS (JR405E) 7A2-71
Step Action Yes No
9 Check if the trouble is caused by a poor connection of terminal
assembly connector.
With the key switch in OFF position, is the connection condition of
the connector and harness correct?
Go to Step 10
Repair the harness
or connector.
Go to Step 12
10 Remove the oil pan. Is the continuity correct between terminal
assembly terminal 7 and 2-4 brake pressure switch connector?

7
Go to Step 11
Repair the harness
or connector.
Go to Step 12
11 Is the result OK when the oil pan is removed and the 2-4 brake
pressure switch is checked? Repair the control
valve.
Go to Step 12
Replace pressure
switch.
Go to Step 12
12 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 13
13 Are the other DTCs outputted?
Go to Other DTC
Section Action is completed