Isuzu Trooper (2000 year). Manual - part 406

7A1–38 TRANSMISSION CONTROL SYSTEM (4L30–E)

DTC P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low Input  (Cont’d)

Step

No

Yes

Action

8

1. Disconnect the internal wiring harness at the TFT sensor.
2. Measure the resistance of the TFT sensor.

Is the resistance within specifications? (See Resistance Chart.)

Go to Diagnostic

Aids

Go to Step 9

9

Replace the TFT Sensor.

Is the replacement complete?

Go to Step 13

—

10

Check circuit RED/WHT for a short to ground.

Was a problem found?

Go to Step 13

Go to Step 11

11

Check the PCM for faulty connections.

Was a problem found?

Go to Step 13

Go to Step 12

12

Replace the PCM. Refer to Powertrain Control Module (PCM) in
Automatic Transmission (4L30–E) section.

Is the replacement complete?

Go to Step 13

—

13

1. After the repair is complete, use the scan tool to select “DTC”,

then “Clear Info” function and ensure the following conditions
are met:
TFT sensor indicates a voltage greater than 0.33 volts for 2
seconds.

2. Review the scan tool “DTC info”.

Has the last test failed or is the current DTC displayed?

Begin diagnosis

again

 Go to Step 1

Repair verified
Exit DTC table

TRANSMISSION CONTROL SYSTEM (4L30–E)

7A1–39

DTC P0713 Transmission Fluid Temperature (TFT) Sensor Circuit High Input

D07RY00010

Circuit Description

The TFT sensor is a thermistor that controls the signal
voltage to the PCM.  The PCM supplies a 5–volt reference
signal to the sensor on circuit RED/WHT.  When the
transmission fluid is cold, the sensor resistance is high
and the PCM will sense high signal voltage.  As the
transmission fluid temperature warms to the normal
operating temperature of 100

°

C (212

°

F), the sensor

resistance becomes less and the voltage decreases to
about 1.5 to 2 volts.
This DTC detects a continuous open or short to power in
the TFT signal circuit or the TFT sensor.  This is a type “D”
DTC.

Conditions For Setting The DTC

D

Battery voltage is between 10 and 16 volts.

D

Ignition is “on”.

D

TFT sensor indicating a voltage greater than 4.86
volts.

D

All conditions met for 20 seconds.

Action Taken When The DTC Sets

D

Transmission default temperature will be:

80

°

C (176

°

F) if engine temperature code is set.

100

°

C (212

°

F) if engine temperature is warm.

80

°

C (176

°

F) if engine run time is greater than 5

minutes.

21

°

C (69.8

°

F) if engine run time is less than 5

minutes.

D

The PCM will not illuminate the Malfunction Indicator
Lamp (MIL).

Conditions For Clearing The DTC

D

The DTC can be cleared from the PCM history by
using a scan tool.  

D

The DTC will be cleared from history when the vehicle
has achieved 40 warmup cycles without a failure
reported.

D

The PCM will cancel the DTC default actions when
the fault no longer exists and the ignition is cycled “off”
long enough to power down the PCM.

Diagnostic Aids

D

Inspect the wiring for poor electrical connection at the
PCM and at the transmission 16–way connectors.
Look for possible bent, backed out, deformed or
damaged terminals.  Check for weak terminal tension
as well.  Also check for a chafed wire that could short
to bare metal or other wiring.  Inspect for a broken wire
inside the insulation.

D

When diagnosing for a possible intermittent short or
open condition, move the wiring harness while
observing test equipment for a change.

D

Scan tool displays transmission fluid temperature in
degrees. After transmission is operating, the
temperature should rise steadily to about 100

°

C

(212

°

F), then stabilize.

D

The temperature to resistance value scale may be
used to check the TFT sensor at the various
temperature levels to evaluate the possibility of a
“skewed” (mis–scaled) sensor.

A “skewed” sensor could result in hard shifts or TCC
complaints.

Test Description

The numbers below refer to the step numbers on the
diagnostic chart:
3. This check verifies problem in the TFT sensor circuit.
4. This test simulates a TFT sensor DTC P0712.  If the

PCM recognizes the low signal voltage (high
temperature), and the scan tool displays 146

°

C

(295

°

F) or greater, the PCM and wiring are OK.

7A1–40 TRANSMISSION CONTROL SYSTEM (4L30–E)

5. This test checks the TFT sensor and internal wiring

harness.

Resistance Chart

°

C

°

F

Resistance (k

m

)

–40

–40

672

0

32

65

20

68

25

80

176

2.5

120

248

0.78

150

304

0.37

DTC P0713 Transmission Fluid Temperature (TFT) Sensor Circuit High Input 

Step

Action

Yes

No

1

Were you sent here from the “Powertrain On–Board Diagnostic
(OBD) System Check”?

Go to Step 2

Go to OBD

System Check

Refer to

Driveability and

Emission in

Engine section

2

Perform the transmission fluid checking procedure.
Refer to Checking Transmission Fluid Level and Condition in
Automatic Transmission (4L30–E) section.

Was the fluid checking procedure performed?

Go to Step 3

Refer to

Checking

Transmission

Fluid Level and

Condition in

Automatic

Transmission

(4L30–E) section

3

1. Install the scan tool.
2. With the engine “off”, turn the ignition switch “on”.

NOTE: Before clearing DTC(s), use the scan tool to record “Freeze
Frame” and “Failure Records” for reference, as data will be lost
when the “Clear Info” function is used.

3. Record the DTC “Freeze Frame” and “Failure Records”.

Does the scan tool display a TFT sensor signal voltage greater
than 4.86 volts?

Go to Step 4

Go to Diagnostic

Aids

4

1. Turn the ignition “off”.
2. Disconnect the transmission 16–way connector H–56.
3. Install a fused jumper wire from terminal M7–4(F) and

M7–1(E) on the engine harness.

4. Turn the ignition “on”.

Does the TFT signal voltage drop to less than 0.4 volts?

Go to Step 5

Go to Step 10

5

1. Turn the ignition “off”.
2. Using the J39200 DVOM, measure the resistance between

terminals M7–4(F) and M7–1(E).

Is the resistance within specifications? (See Resistance Chart.)

Go to Diagnostic

Aids

Go to Step 6

6

1. Disconnect the transmission 7–way connector M–7.
2. Using the J39200 DVOM, measure the resistance between

terminals M7–4(F) and M7–1(E).

Is the resistance within specifications? (See Resistance Chart.)

Go to Diagnostic

Aids

Go to Step 7

TRANSMISSION CONTROL SYSTEM (4L30–E)

7A1–41

DTC P0713 Transmission Fluid Temperature (TFT) Sensor Circuit High Input  (Cont’d)

Step

No

Yes

Action

7

1. Remove the transmission oil pan.
2. Check the internal wiring harness for an open. Refer to

Transmission Oil Temperature Sensor (Main Case) in
Automatic Transmission (4L30–E) section.

Was a problem found and corrected?

Go to Step 14

Go to Step 8

8

1. Disconnect the internal wiring harness at the TFT sensor.
2. Measure the resistance of the TFT sensor.

Is the resistance within specifications? (See Resistance Chart.)

Go to Diagnostic

Aids

Go to Step 9

9

Replace TFT sensor. Refer to Transmission Oil Temperature
Sensor (Main Case) in Automatic Transmission (4L30–E)
section.

Is the replacement complete?

Go to Step 14

—

10

Check circuit RED/WHT for an open or short to B+.

Was a problem found?

Go to Step 14

Go to Step 11

11

Check circuit RED/BLK for an open.

Was a problem found?

Go to Step 14

Go to Step 12

12

Check the PCM for faulty or intermittent connections.

Was a problem found?

Go to Step 14

Go to Step 13

13

Replace the PCM. Refer to Powertrain Control Module (PCM) in
Automatic Transmission (4L30–E) section.

Is the replacement complete?

Go to Step 14

—

14

1. After the repair is complete, use the scan tool to select “DTC”,

then “Clear Info” function and ensure the following conditions
are met:

2. TFT sensor indicates a voltage less than 4.92 volts for 2

seconds.

3. Review the scan tool “DTC Info”.

Has the last test failed or is the current DTC displayed?

Begin diagnosis

again

Go to Step 1

Repair verified
Exit DTC table