Isuzu KB P190. Manual - part 1086

 

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Isuzu KB P190. Manual - part 1086

 

 

7A2-60   TRANSMISSION CONTROL SYSTEM (JR405E)

10

1.

Remove the transmission oil pan. Refer to
repair instructions (On-Vehicle Service). 

2.

Inspect the low & reverse brake solenoid valve
for the following conditions:

• Physical damage of solenoid valve 

• Loose or improper installation of solenoid

valve

3.

Inspect for an intermittent and for a poor
connection at the harness connector of the
low & reverse brake solenoid valve or in-line
harness connector. 

4.

Inspect for an intermittent and for a poor
connection of ground wire. 

5.

Test the control circuit between the low &
reverse brake solenoid valve and the in-line
harness connector (pin 5 of E-54 male side)
for the following conditions:

• An open circuit

• A short to ground

• A short to the other solenoid valve circuit

• High resistance 

6.

Repair the connection(s) or circuit(s) as
necessary.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

11

Replace the low & reverse brake solenoid valve.
Refer to repair instructions (On-Vehicle Service). 

Did you complete the replacement?

Go to Step 13

12

Important: Replacement TCM must be
programmed.
Replace the TCM. Refer to TCM Replacement.

Did you complete the replacement?

Go to Step 13

13

1.

Reconnect all previously disconnected
components or harness connector(s).

2.

Clear the DTCs with a scan tool.

3.

Turn OFF the ignition for 30 seconds. 

4.

Start the engine.

5.

Lift the driving wheels or drive the vehicle
while observing the DTC Information with a
scan tool. 

Did the DTC fail this ignition?

Go to Step 4

Go to Step 14

14

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

Go to DTC List 

System OK

Step

Action

Value(s)

Yes

No

TRANSMISSION CONTROL SYSTEM (JR405E)   7A2-61

DTC P0758 (Flash Code 32)

Circuit Description

The 2-4 brake solenoid valve controls fluid acting on
spool valves in the 2-4 brake hydraulic circuits, which
then controls 2-4 brake apply and release. The
solenoid valve is installed to the lower part of the valve
body assembly. The TCM controls the solenoid valve
by a duty cycle (pulse width modulation [PWM]) signal
based on the commanded gear position. The solenoid
valve provides a smooth gearshift by operating on a
duty cycle percentage of ON time. The TCM monitors
the 2-4 brake solenoid valve operating status through
the feedback circuit. If the TCM detects an improper
voltage level on the control circuit, this DTC will set. 

Condition for Running the DTC

• The ignition switch is ON.

Condition for Setting the DTC

• The TCM detects an open circuit or short circuit on

the 2-4 brake solenoid valve control circuit.

 Action Taken When the DTC Sets

• The TCM blinks the Check Trans lamp when the

diagnostic runs and fails.

During the vehicle running;

• The TCM holds the last gear position when the

diagnostic runs and fails.

• The TCM stops 2-4 brake solenoid valve. 

• The TCM inhibits lock up control.

After the vehicle stopped;

• The TCM stops all shift solenoid valves and fixes

to the 3rd gear. If a fail-safe valve problem is
detected, the shift solenoid valves are not stopped
but gear is fixed to the 3rd gear.

• The TCM stops PC solenoid valve. 

Condition for Clearing the DTC

• The TCM turns OFF the Check Trans lamp when

the diagnostic runs and does not fail at next
ignition cycle.

• A current DTC clears when the diagnostic runs and

does not fail at next ignition cycle.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

• Use the Clutch, Brake, Solenoid and Pressure

Switch Logic table to verify each component works
properly within the selected gear range.

Schematic Reference: Transmission Controls
Schematics
Connector End View Reference: Transmission
Controls Connector End Views or TCM Connector End
Views

Circuit/ System Testing DTC P0758

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check -
Transmission Controls?

Go to Step 2

Go to Diagnostic 

System Check -

Transmission 

Controls

2

1.

Install a scan tool. 

2.

Turn OFF the ignition for 30 seconds. 

3.

Lift the driving wheels or drive the vehicle
while observing the DTC Information with a
scan tool.

Is DTC P1875 also set?

Go to DTC P1875

Go to Step 3

3

1.

Park the vehicle.

2.

Turn ON the ignition, with the engine OFF.

3.

Perform the 2-4 Brake Solenoid control with a
scan tool.

4.

Command the solenoid valve ON and OFF.

Does the 2-4 brake solenoid valve click with each
command?

Go to Diagnostic 

Aids

Go to Step 4

7A2-62   TRANSMISSION CONTROL SYSTEM (JR405E)

4

1.

Turn OFF the ignition. 

2.

Disconnect the in-line harness connector (E-
54) near the transmission range switch.

3.

Connect a test lamp between the control
circuit (pin 9 of E-54 female side) and a known
good ground. 

4.

Turn ON the ignition, with the engine OFF.

5.

Perform the 2-4 Brake Solenoid control with a
scan tool.

6.

Command the solenoid valve ON and OFF.

Does the test lamp turn ON and OFF with each
command?

Go to Step 9

Go to Step 5

5

Does the test lamp remain illuminated with each
command?

Go to Step 6

Go to Step 7

6

1.

Test the control circuit between the TCM (pin 7
of C-95) and the in-line harness connector (pin
9 of E-54 female side) for a short to battery or
ignition voltage. 

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

Go to Step 13

Go to Step 12

7

1.

Test the control circuit between the TCM (pin 7
of C-95) and the in-line harness connector (pin
9 of E-54 female side) for the following
conditions:

• An open circuit

• A short to ground

• High resistance 

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

Go to Step 13

Go to Step 8

8

1.

Turn OFF the ignition. 

2.

Disconnect the TCM harness connector.

3.

Inspect for an intermittent and for a poor
connection at the harness connector of the
TCM (pin 7 of C-95). 

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

Go to Step 13

Go to Step 12

9

1.

Inspect for an intermittent and for a poor
connection at the in-line harness connector
(pin 9 of E-54).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

Step

Action

Value(s)

Yes

No

TRANSMISSION CONTROL SYSTEM (JR405E)   7A2-63

10

1.

Remove the transmission oil pan. Refer to
repair instructions (On-Vehicle Service). 

2.

Inspect the 2-4 brake solenoid valve for the
following conditions:

• Physical damage of solenoid valve 

• Loose or improper installation of solenoid

valve

3.

Inspect for an intermittent and for a poor
connection at the harness connector of the 2-
4 brake solenoid valve or in-line harness
connector.

4.

Inspect for an intermittent and for a poor
connection of ground wire. 

5.

Test the control circuit between the 2-4 brake
solenoid valve and the in-line harness
connector (pin 9 of E-54 male side) for the
following conditions:

• An open circuit

• A short to ground

• A short to the other solenoid valve circuit

• High resistance 

6.

Repair the connection(s) or circuit(s) as
necessary.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

11

Replace the 2-4 brake solenoid valve. Refer to
repair instructions (On-Vehicle Service). 

Did you complete the replacement?

Go to Step 13

12

Important: Replacement TCM must be
programmed.
Replace the TCM. Refer to TCM Replacement.

Did you complete the replacement?

Go to Step 13

13

1.

Reconnect all previously disconnected
components or harness connector(s).

2.

Clear the DTCs with a scan tool.

3.

Turn OFF the ignition for 30 seconds. 

4.

Start the engine.

5.

Lift the driving wheels or drive the vehicle
while observing the DTC Information with a
scan tool. 

Did the DTC fail this ignition?

Go to Step 4

Go to Step 14

14

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

Go to DTC List 

System OK

Step

Action

Value(s)

Yes

No

 

 

 

 

 

 

 

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