Isuzu Trooper (2000 year). Manual - part 405

7A1–34 TRANSMISSION CONTROL SYSTEM (4L30–E)

D

When diagnosing for an intermittent short or open
connection, move the wiring harness while watching
the test equipment for a change.

D

First diagnose and clear any engine DTCs or TP
Sensor codes. Then inspect for any transmission
DTCs that may have reset.

Test Description

The number below refers to the step number on the
diagnostic chart:
3. This test checks PCM and associated wiring up to

the 16–way connectors. If the voltage increases to
match chart the problem is isolated to the
transmission wiring.

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 P0711 Transmission Fluid Temperature (TFT) Sensor Performance 

Step

Action

Yes

No

1

Was the Powertrain On–Board Diagnostic (OBD) System Check
performed?

Go to Step 2

Go to OBD

System Check

Refer to

Driveability and

Emissions in

Engine section

2

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

Did you perform the fluid checking procedure?

Go to Step 3

Go 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 to the “on”

position.

NOTE: Before clearing DTCs, use the scan tool in order to record
the Freeze Frame and Failure Records for reference. The Clear
Info function will erase the data. 

3. Record the DTC Freeze Frame and Failure Records.
4. Select TFT on the scan tool.
5. While observing the scan tool display, move or massage the

engine wiring harness from PCM connectors J2–66 and J2–20
to the transmission 16–way connectors.

Does the TFT change by more than 

±

20

°

C (36

°

F)?

Go to Step 6

Go to Step 4

4

1. Turn the ignition “off”.
2. Disconnect the transmission 16–way connector H–56.
3. Install Jumper Harness on the transmission side of the

16–way connector H–56.

4. Using the J39200 DVOM and J35616 Connector Test Adapter

Kit, connect the DVOM leads from terminal M7–4(F) to
terminal M7–1(E).

5. Set the DVOM on MIN/MAX to measure resistance.
6. Record the TFT sensor resistance.
7. Move or massage the automatic transmission wiring harness

assembly from the 16–way connector H–56 to the TFT sensor
connector.

Does the DVOM MAX display a resistance greater than the value
recorded in Action item 6 of this step?

Go to Step 7

Go to Step 5

5

Does the DVOM MIN display a resistance less than the value
recorded in Action item 6 of step 4?

Go to Step 8

—

TRANSMISSION CONTROL SYSTEM (4L30–E)

7A1–35

DTC P0711 Transmission Fluid Temperature (TFT) Sensor Performance  (Cont’d)

Step

No

Yes

Action

6

Inspect circuit RED/WHT and RED/BLK of the engine wiring
harness for an intermittent open or short condition. Repair the
circuits if necessary.

Did you find a problem?

Go to Step 12

Go to Step 11

7

Inspect the automatic transmission wiring harness assembly for
an intermittent open in circuits RED/WHT and RED/BLK.

Did you find a problem?

Go to Step 9

Go to Step 10

8

Inspect the automatic transmission wiring harness assembly for
an intermittent shorted condition in circuits RED/WHT and
RED/BLK.

Did you find a problem?

Go to Step 9

Go to Step 10

9

Replace the automatic transmission wiring harness assembly.

Is the replacement complete?

Go to Step 12

—

10

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

Is the replacement complete?

Go to Step 12

—

11

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

Is the replacement complete?

Go to Step 12

—

12

In order to verify your repair, perform the following procedure.
1. Select DTC.
2. Select Clear Info.
3. Drive the vehicle and ensure the following conditions are met:

D

The TFT changes by more than 2.25

°

C (4.05

°

F) for 11

seconds since startup.

D

The TFT does not change by more than 20

°

C (36

°

F) within

0.200 second for a period of at least 11 seconds.

4. Select Specific DTC.
5. Enter DTC P0711.

Has the test run and passed?

System OK

Begin the

diagnosis again

 Go to Step 1

7A1–36 TRANSMISSION CONTROL SYSTEM (4L30–E)

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

D07RY00010

Circuit Description

The TFT sensor is a thermister 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.
The PCM detects high signal voltage.  As the
transmission fluid temperature increases to the normal
operating temperature of 100

°

C (212

°

F), the sensor

resistance becomes less and the voltage decreases to
1.5 to 2 volts.  With transmission fluid over temperature
and DTC P0218 also set, check the transmission cooling
system.
This DTC detects a continuous short to ground 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 less than 0.4 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

Check harness routing for a potential short to ground
in circuit RED/BLK. Scan tool TFT display should rise
steadily to about 100

°

C (212

°

F), then stabilize.

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

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

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

D

Verify customer driving habits, trailer towing, etc.

Test Description

The numbers below refer to the step numbers on the
diagnostic chart:
3. This test checks for a short to ground or a “skewed”

sensor.

4. This test checks for an internal fault within the

transmission by creating an open.

TRANSMISSION CONTROL SYSTEM (4L30–E)

7A1–37

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 P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low 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

Emissions 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 less than
0.4 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. Turn the ignition “on”.

Does the TFT signal voltage change to match the voltage 4.92
volts?

Go to Step 5

Go to Step 10

5

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

7

1. Remove the transmission oil pan.  Refer to Transmission Oil

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

2. Check the internal wiring harness for a short to ground.

Was a problem found?

Go to Step 9

Go to Step 8