Tcm ISUZU TF SERIES 2004 Workshop Manual

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

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

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

7A2-72 DIAGNOSIS (JR405E)
DTC P1863 (Flash Code 28) High Clutch 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) 7A2-73

Setting Condition:

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

Fail Safe:

No fail safe function

Possible Cause:

High clutch duty solenoid malfunction.

High clutch pressure switch open circuit or short circuit.

Open circuit, short circuit to battery or short circuit to ground of the harness between high clutch pressure switch
terminal 1 and TCM terminal B20 (C95).

High clutch hydraulic circuit malfunction in the control valve.

Poor connection of each connector.

Reference:
When the high clutch pressure switch is operated, following signal is outputted.
Measurement terminal: B20 (C95) and B22 (C95)
-At other than 3rd or 4th gear: More than 10V
-At 3rd or 4th gear: Less than 1V

DIAGNOSIS (JR405E) 7A2-75
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 1 and high clutch pressure switch connector?

1
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 high clutch
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

7A2-76 DIAGNOSIS (JR405E)
DTC P0731 (Flash Code 41) 1st Gear Ratio Error
DTC P0732 (Flash Code 42) 2nd Gear Ratio Error
DTC P0733 (Flash Code 43) 3rd Gear Ratio Error
DTC P0734 (Flash Code 44) 4th Gear Ratio Error

Pre-setting Condition:

No other DTCs.

2 seconds elapsed after D, 3, 2, or 1 range was selected.

Vehicle is running at the vehicle speed over 10 km/h with the turbine speed over 1000 rpm.

Except at the gear shifting.

ATF temperature more than 60C.

No fail safe valve malfunction.

Setting Condition:
In the case pre-setting conditions are met, the TCM calculates the turbine speed that corresponds to the gear ratio
of the outputted solenoid pattern in about 7 seconds after each gear shift has completed, and when the output shaft
speed against the turbine speed exceeds 500 rpm.

Fail Safe:

No fail safe function

Possible Cause:

Turbine sensor or speed sensor malfunction.

Shift solenoid malfunction.

Clutch slipping.

Step Action Yes No
1 Turn the key switch on and check the DTC. Are the DTC other
than gear ratio error outputted? Go to Other DTC
Section Go to Step 2
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 gear shift is repeated 3 times from 1st to 4th in the D
range? Go to Other DTC
Section Go to Step 3
3 Check again the DTC. Are all codes indicating gear ratio error
outputted?

Even if one of DTC
indicating gear ratio
error is outputted
Go to step 5

Go to Step 4
DTC indicating gear
ratio error are not
outputted at all.
Go to step 9
4 Check the turbine sensor and the speed sensor for function. Is
the result OK?
Go to Step 9
Replace turbine speed
sensor.
Go to Step 9
5 Are the color and smell of ATF normal? Go to Step 6 Go to Step 9