Isuzu KB P190. Manual - part 1081

7A2-40   TRANSMISSION CONTROL SYSTEM (JR405E)

DTC P0710 (Flash Code 15)

Circuit Description

The transmission fluid temperature (TFT) sensor is
attached to the lower part of the valve body assembly.
The TFT sensor is a variable resistor and it measures
the temperature of the transmission fluid. The sensor
has a signal circuit and a low reference circuit. The
TCM supplies 2.5 volts to the signal circuit and a
ground for the low reference circuit. When the TFT
sensor is cold, the sensor resistance is high. When the
transmission fluid temperature increases, the sensor
resistance decreases. With high sensor resistance, the
TCM detects a high voltage on the signal circuit. With
lower sensor resistance, the TCM detects a lower
voltage on the signal circuit. If the TCM detects an
excessively low or high signal voltage, this DTC will set.

Condition for Running the DTC

• The ignition switch is ON. 

Condition for Setting the DTC

Either of following condition is met:

• The TCM detects that the TFT sensor signal

voltage is less than 0.1 volts (more than 146

°C

[295

°F]) when the selector lever is P or N range for

longer than 5 minutes. 

• The TCM detects that the TFT sensor signal

voltage is more than 2.43 volts (less than -40

°C [-

40

°F]) for 10 seconds when the vehicle speed is

more than 20 km/h (12 MPH). 

Action Taken When the DTC Sets

• The TCM does not blink the Check Trans lamp.

• The TCM inhibits 4th gear. (If the engine speed is

more than 470 PRM for 10 minutes, shifting to 4th
gear is allowed.)

• The TCM inhibits lock up control. (If the engine

speed is more than 470 RPM for 10 minutes, lock
up control is allowed.)

• The TCM uses a TFT substitution of 80

°C (176°F)

for transmission control.

Condition for Clearing the DTC

• current 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.

• Use the Temperature vs. Resistance table to test

the TFT sensor at various temperature levels to
evaluate the possibility of a skewed sensor. A
skewed sensor could result in poor driveability
(poor shift quality) concerns.

Test Description

The numbers below refer to the step number on the
Circuit/ System Testing. 
5. If the TFT sensor signal circuit is shorted to ground,
A/T Oil Temp lamp turns ON and the TCM switches
shift map to the high temperature mode until this DTC
is set.
Schematic Reference: Transmission Controls
Schematics
Connector End View Reference: Transmission
Controls Connector End Views or TCM Connector End
Views

Circuit/ System Testing DTC P0710

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 ON the ignition, with the engine OFF.

3.

Observe the Transmission Fluid Temperature
(TFT) parameter with a scan tool within 5
minutes from the ignition switch is ON.

Is the TFT parameter more than the specified
value?

146

°C (295°F)

Go to Step 4

Go to Step 3

3

Is the TFT parameter less than the specified value
at Step 2?

-40

°C (-40°F)

Go to Step 7

Go to Diagnostic 

Aids

TRANSMISSION CONTROL SYSTEM (JR405E)   7A2-41

4

1.

Turn OFF the ignition. 

2.

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

3.

Turn ON the ignition, with the engine OFF.

Is the TFT parameter less than the specified value?

-40

°C (-40°F)

Go to Step 14

Go to Step 5

5

1.

Test the signal circuit between the TCM (pin 4
of C-95) and the in-line harness connector (pin
2 of E-54) for the following conditions:

• A short to ground

• A short to the low reference circuit

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 6

6

1.

Turn OFF the ignition.

2.

Disconnect the TCM harness connector.

3.

Inspect connections at the harness connector
of the TCM (pins 4 and 14 of C-95) for
corrosion.

4.

Repair or clean the connection(s) as
necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 17

7

1.

Turn OFF the ignition. 

2.

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

3.

Connect a DMM between the signal circuit
(pin 2 of E-54) and a known good ground.

4.

Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified value?

2.8 volts

Go to Step 8

Go to Step 9

8

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

1.

Test the signal circuit between the TCM (pin 4
of C-95) and the in-line harness connector (pin
2 of E-54) for the following conditions: 

• A short to battery or ignition voltage

• A short to any 5 volts reference 

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 17

9

Connect a 3-amp fused jumper wire between the
signal circuit and the low reference circuit (pins 2
and 8 of E-54). 

Is the TFT parameter more than the specified
value?

146

°C (295°F)

Go to Step 13

Go to Step 10

10

Connect a 3-amp fused jumper wire between the
signal circuit (pin 2 of E-54) and a known good
ground.

Is the TFT parameter more than the specified
value?

146

°C (295°F)

Go to Step 12

Go to Step 11

Step

Action

Value(s)

Yes

No

7A2-42   TRANSMISSION CONTROL SYSTEM (JR405E)

11

1.

Test the signal circuit between the TCM (pin 4
of C-95) and the in-line harness connector (pin
2 of E-54) for an open circuit or high
resistance. 

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 15 

12

1.

Test the low reference circuit between the
TCM (pin 14 of C-95) and the in-line harness
connector (pin 8 of E-54) for an open circuit or
high resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 15

13

1.

Inspect for an intermittent and for poor
connections at the in-line harness connector
(pins 2 and 8 of E-54).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 14

14

1.

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

2.

Test the signal circuit between the TFT sensor
and the in-line harness connector (pin 2 of E-
54) for the following conditions:

• An open circuit

• A short to ground

• A short to the low reference 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
8 of E-54) for an open circuit or high
resistance. 

4.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 16

15

1.

Turn OFF the ignition. 

2.

Disconnect the TCM harness connector.

3.

Inspect for an intermittent and for poor
connections at the harness connector of the
TCM (pins 4 and 14 of C-95). 

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 17

16

Replace the TFT sensor. Refer to repair
instructions (On-Vehicle Service). (TFT sensor is
part of the harness assembly)

Did you complete the replacement?

—

Go to Step 18

—

17

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

Did you complete the replacement?

—

Go to Step 18

—

Step

Action

Value(s)

Yes

No

TRANSMISSION CONTROL SYSTEM (JR405E)   7A2-43

18

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.

Operate the vehicle within the Conditions for
Running the DTC. 

Did the DTC fail this ignition?

—

Go to Step 2

Go to Step 19

19

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