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Isuzu N-Series. Manual - part 905

Transmission Control System (Smoother) 7A-75

1. Turn OFF the ignition.
2. Inspect for an intermittent and for poor

connections at the in-line harness connector
(pins 2 and 4 of J-237 connector).

3. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 19

Go to Step 13

1. Turn OFF the ignition.
2. Disconnect the TCM harness connector.
3. Inspect for an intermittent and for poor

connections on the TFT sensor circuits at the
harness connector of the TCM (pins 6 and 12
of B-427 connector).

4. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 19

Go to Step 18

1. Remove the harness assembly from the oil

pump. Refer to Repair Instructions (Overhaul)
- Oil Pump in this section.

2. Test the signal circuit between the TFT sensor

and the in-line harness connector (pin 2 of J-
237 connector) for the following conditions:

• An open circuit
• A short to the solenoid valve circuit
• High resistance

3. Test the low reference circuit between the TFT

sensor and the in-line harness connector (pin
4 of J-237 connector) for an open circuit or
high resistance.

4. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 19

Go to Step 17

1. Turn OFF the ignition.
2. Disconnect the in-line harness connector (J-

237) near the starter motor.

3. Connect a DMM between the signal circuit of

the TFT sensor harness (pin 2 of J-237 female
connector) and a known good ground.

4. Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified value?

4.5 volts

Go to Step 16

Go to Step 15

1. Test the signal circuit between the TCM (pin 6

of B-427 connector) and the in-line harness
connector (pin 2 of J-237 connector) for a short
to ground or short to the low reference circuit.

2. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 19

Go to Step 18

1. Test the signal circuit between the TFT sensor

and the in-line harness connector (pin 2 of J-
237 connector) for a short to ground or short to
the low reference circuit.

2. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 19

Go to Step 17

Replace the TFT sensor. Refer to Repair
Instructions (Overhaul) - Oil Pump in this section.
(TFT sensor is part of the harness assembly)

Did you complete the replacement?

—

Go to Step 19

—

Step

Action

Value(s)

Yes

7A-76 Transmission Control System (Smoother)

Important:
Replacement TCM must be programmed and
learned.
Replace the TCM. Refer to Transmission Control
Module (TCM) Replacement in this section.

Did you complete the replacement?

—

Go to Step 19

—

1. Reconnect all previously disconnected

harness connector(s).

2. Clear the DTCs with the Tech 2.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Operate the vehicle within the Conditions for

Running the DTC.

Did the DTC fail this ignition?

—

Go to Step 2

Go to Step 20

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic

Trouble Code (DTC)

List

System OK

Step

Action

Value(s)

Yes

Transmission Control System (Smoother) 7A-77

P0715 (Flash Code 3)

Circuit Description
The turbine speed sensor is located on right-hand side
of the fluid coupling housing. The turbine speed sensor
is a magnetic coil type sensor, which generates an AC
signal voltage based on the gearshift multi-plate clutch
rotational speed that is part of the sub-hub assembly
attached to the fluid coupling turbine by spline. (30
pulses per a rotation of the gearshift multi-plate clutch)
If the transmission control module (TCM) detects no
turbine speed sensor signal during the lock up clutch is
engaged, this DTC will set.
Condition for Running the DTC

• DTCs P0721, P0726, U0400 and U0406 are not

set.

• The ignition switch is ON.
• The ignition voltage is more than 20 volts.
• The emergency switch is OFF.
• The engine is running.
• The lock up clutch is commanded engage.

Condition for Setting the DTC

• The TCM detects that the turbine speed sensor

pulses are not generated during lock up control.

Action Taken When the DTC Sets

• The TCM illuminates the transmission warning

lamp when the diagnostic runs and fails.

• The TCM inhibits gear select & shift position

learning and half-clutch learning.

Condition for Clearing the DTC

• The TCM turns OFF the transmission warning

lamp when the diagnostic runs and does not fail.

• A current DTC clears when the diagnostic runs and

does not fail.

• A history DTC clears when the diagnostic runs and

does not fail.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

• Electrical or magnetic interference may affect

intermittent condition.

• Ensure the sensor is tight and the gearshift multi-

plate clutch case is not damaged.

• If this DTC is present, harsh garage shift appears

when shifted from N to D or N to R.

DTC P0715 (Flash Code 3)

Schematic Reference: Transmission Controls
Schematics
Connector End View Reference: Transmission
Controls Connector End Views or Transmission Control
Module (TCM) Connector End Views

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check -
Transmission Controls?

—

Go to Step 2

Go to Diagnostic

System Check -

Transmission

Controls

1. Install the Tech 2.
2. Turn OFF the ignition for 30 seconds.
3. Place the transmission in neutral and set the

parking brake.

4. Start the engine.
5. Observe the Turbine Speed parameter with

the Tech 2 while accelerating the engine
between idle and W.O.T. (accelerator pedal
full travel).

Does the Turbine Speed parameter increase in
accordance with an engine speed increase?

—

Go to Diagnostic

Aids

Go to Step 3

1. Turn OFF the ignition.
2. Disconnect the turbine speed sensor harness

connector.

3. Connect a DMM across the turbine speed

sensor terminals.

4. Measure the resistance across the turbine

speed sensor.

Does the turbine speed sensor resistance measure
within the specified range?

1.0 - 2.5k

Ω

Go to Step 4

Go to Step 16

7A-78 Transmission Control System (Smoother)

1. Connect a DMM across the turbine speed

sensor terminals (measure sensor output
voltage).

2. Place the DMM on the AC volt scale.
3. Start the engine.
4. Monitor the DMM while accelerating the

engine between idle and W.O.T. (accelerator
pedal full travel).

Does the DMM indicate an AC voltage increase in
accordance with an engine speed increase?

—

Go to Step 5

Go to Step 15

1. Connect a DMM between the signal circuit of

the turbine speed sensor harness (pin 2 of J-
232 connector) and a known good ground.

2. Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified value?

5.5 volts

Go to Step 9

Go to Step 6

Is the DMM voltage more than the specified value at
Step 5?

4.5 volts

Go to Step 7

Go to Step 11

1. Connect a test lamp between the signal circuit

of the turbine speed sensor harness (pin 2 of
J-232 connector) and a known good ground.

2. Connect a DMM between the probe of the test

lamp and a known good ground.

3. Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified value?

4.5 volts

Go to Step 10

Go to Step 8

1. Connect a DMM across the signal circuit and

the low reference circuit of the turbine speed
sensor harness (pins 1 and 2 of J-232
connector).

2. Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified value?

4.5 volts

Go to Step 13

Go to Step 12

Important:
The turbine speed sensor may be damaged if the
sensor signal circuit is shorted to a voltage source.

1. Test the signal circuit between the

transmission control module (TCM) (pin 4 of B-
427 connector) and the turbine speed sensor
connector (pin 2 of J-232 connector) 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 18

Go to Step 17

1. Test the signal circuit between the TCM (pin 4

of B-427 connector) and the turbine speed
sensor harness connector (pin 2 of J-232
connector) for a short to any 5 volts reference
circuit.

2. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 17

Step

Action

Value(s)

Yes

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