1998 ISUZU TROOPER transmission fluid

7A1±36
TRANSMISSION CONTROL SYSTEM (4L30±E)
DTC P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low Input
D07RW029
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/BLK±GRN/RED.
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 ªDº DTC.
Conditions For Setting The DTC

Battery voltage is between 10 and 16 volts.

Ignition is ªonº.

TFT sensor indicating a voltage less than 0.4 volts.

All conditions met for 20 seconds.
Action Taken When The DTC Sets

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.

The PCM will not illuminate the CHECK TRANS
Lamp.
Conditions For Clearing The DTC

The DTC can be cleared from the PCM history by
using a scan tool.
The DTC will be cleared from history when the vehicle
has achieved 40 warmup cycles without a failure
reported.

The PCM will cancel the DTC default actions when
the fault no longer exists and the ignition is cycled ªoffº
long enough to power down the PCM.
Diagnostic Aids

Check harness routing for a potential short to ground
in circuit RED/BLK±GRN/RED. Scan tool TFT
display should rise steadily to about 100
C (212
F),
then stabilize.

Inspect the wiring for poor electrical connection at the
PCM and at the transmission 16±way connector.
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.

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

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
ªskewedº (mis±scaled) sensor.
A ªskewedº sensor could result in delayed garage
shifts or TCC complaints.

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 ªskewedº
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

FResistance (k
)
±40±40672
03265
206825
801762.5
1202480.78
1503040.37
DTC P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low Input
StepActionYe sNo
1Perform 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 2
Refer to
Checking
Transmission
Fluid Level and
Condition in
Automatic
Transmission
(4L30±E) section
21. Install the scan tool.
2. With the engine ªoffº, turn the ignition switch ªonº.
NOTE: Before clearing DTC(s), use the scan tool to record ªFreeze
Frameº and ªFailure Recordsº for reference, as data will be lost
when the ªClear Infoº function is used.
3. Record the DTC ªFreeze Frameº and ªFailure Recordsº.
Does the scan tool display a TFT sensor signal voltage less than
0.4 volts?
Go to Step 3
Go to Diagnostic
Aids
31. Turn the ignition ªoffº.
2. Disconnect the transmission 16±way connector H±53.
3. Turn the ignition ªonº.
Does the TFT signal voltage change to match the voltage 4.92
volts?
Go to Step 4Go to Step 9
4Using the J39200 DVOM, measure the resistance between
terminals 3(C) and 5 (D).
Is the resistance within specifications? (See Resistance Chart.)
Go to Diagnostic
Aids
Go to Step 5
51. Disconnect the transmission 5±way connector M±6.
2. Using the J39200 DVOM, measure the resistance between
terminals 3(C) and 5(D).
Is the resistance within specifications? (See Resistance Chart.)
Go to Diagnostic
Aids
Go to Step 6
61. Remove the transmission oil pan. Refer to Transmission Oil
Temperature Sensor (Adapter 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 8Go to Step 7
71. 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 8
8Replace the TFT Sensor.
Is the replacement complete?
Go to Step 12Ð

7A1±38
TRANSMISSION CONTROL SYSTEM (4L30±E)
DTC P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low Input (Cont'd)
StepNo Ye s Action
9Check circuit RED/BLK±GRN/RED for a short to ground.
Was a problem found?
Go to Step 12Go to Step 10
10Check the PCM for faulty connections.
Was a problem found?
Go to Step 12Go to Step 11
11Replace the PCM. Refer to Powertrain Control Module (PCM) in
Automatic Transmission (4L30±E) section.
Is the replacement complete?
Go to Step 12Ð
121. After the repair is complete, use the scan tool to select ªDTCº,
then ªClear Infoº 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 ªDTC infoº.
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
D07RW029
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/BLK±GRN/RED.
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 ªDº
DTC.
Conditions For Setting The DTC

Battery voltage is between 10 and 16 volts.

Ignition is ªonº.

TFT sensor indicating a voltage greater than 4.86
volts.

All conditions met for 20 seconds.
Action Taken When The DTC Sets

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.

The PCM will not illuminate the CHECK TRANS
Lamp.
Conditions For Clearing The DTC

The DTC can be cleared from the PCM history by
using a scan tool.
The DTC will be cleared from history when the vehicle
has achieved 40 warmup cycles without a failure
reported.

The PCM will cancel the DTC default actions when
the fault no longer exists and the ignition is cycled ªoffº
long enough to power down the PCM.
Diagnostic Aids

Inspect the wiring for poor electrical connection at the
PCM and at the transmission 16±way connector.
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.

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

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.

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
ªskewedº (mis±scaled) sensor.
A ªskewedº 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

FResistance (k
)
±40±40672
03265
206825
801762.5
1202480.78
1503040.37
DTC P0713 Transmission Fluid Temperature (TFT) Sensor Circuit High Input
StepActionYe sNo
1Perform 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 2
Refer to
Checking
Transmission
Fluid Level and
Condition in
Automatic
Transmission
(4L30±E) section
21. Install the scan tool.
2. With the engine ªoffº, turn the ignition switch ªonº.
NOTE: Before clearing DTC(s), use the scan tool to record ªFailure
Recordsº for reference, as data will be lost when the ªClear Infoº
function is used.
3. Record the DTC ªFreeze Frameº and ªFailure Recordsº.
Does the scan tool display a TFT sensor signal voltage greater
than 4.86 volts?
Go to Step 3
Go to Diagnostic
Aids
31. Turn the ignition ªoffº.
2. Disconnect the transmission 16±way connector H±53.
3. Install a fused jumper wire from terminal 3(C) to 5(D) on the
engine harness.
4. Turn the ignition ªonº.
Does the TFT signal voltage drop to less than 0.4 volts?
Go to Step 4Go to Step 9
41. Turn the ignition ªoffº.
2. Using the J39200 DVOM, measure the resistance between
terminals 3(C) and 5(D).
Is the resistance within specifications? (See Resistance Chart.)
Go to Diagnostic
Aids
Go to Step 5
51. Disconnect the transmission 5±way connector M±6.
2. Using the J39200 DVOM, measure the resistance between
terminals 3(C) and 5(D).
Is the resistance within specifications? (See Resistance Chart.)
Go to Diagnostic
Aids
Go to Step 6
61. Remove the transmission oil pan.
2. Check the internal wiring harness for an open. Refer to
Transmission Oil Temperature Sensor (Adapter Case) in
Automatic Transmission (4L30±E) section.
Was a problem found and corrected?
Go to Step 13Go to Step 7
71. 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 8

TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±41
DTC P0713 Transmission Fluid Temperature (TFT) Sensor Circuit High Input (Cont'd)
StepNo Ye s Action
8Replace TFT sensor. Refer to Transmission Oil Temperature
Sensor (Adapter Case) in Automatic Transmission (4L30±E)
section.
Is the replacement complete?
Go to Step 13Ð
9Check circuit RED/BLK±GRN/RED for an open or short to B+.
Was a problem found?
Go to Step 13Go to Step 10
10Check circuit GRY±GRN for an open.
Was a problem found?
Go to Step 13Go to Step 11
11Check the PCM for faulty or intermittent connections.
Was a problem found?
Go to Step 13Go to Step 12
12Replace the PCM. Refer to Powertrain Control Module (PCM) in
Automatic Transmission (4L30±E) section.
Is the replacement complete?
Go to Step 13Ð
131. After the repair is complete, use the scan tool to select ªDTCº,
then ªClear Infoº 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 ªDTC Infoº.
Has the last test failed or is the current DTC displayed?
Begin diagnosis
again
Go to Step 1
Repair verified
Exit DTC table

7A1±52
TRANSMISSION CONTROL SYSTEM (4L30±E)
Conditions For Clearing The DTC/CHECK
TRANS Lamp

The PCM will turn ªoffº the CHECK TRANS Lamp
after three consecutive ignition cycles without a
failure reported.

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

The DTC can also be cleared from memory when the
vehicle has made 40 warmup cycles without a failure
reported.

The PCM will cancel the DTC Actions Taken items
when the fault conditions no longer exist and the
ignition is cycles ªoffº long enough to power down the
PCM.
Diagnostic Aids

Check for intermittent output speed sensor circuit
problems.

Check for possible incorrect calibration. (PCM part
No., tire specification, and rear axle ratio)
Test Description
The numbers below refer to the step numbers on the
diagnostic chart:
3. This step checks for possible low fluid level causing
slipping resulting in an undefined gear ratio.
4. This step checks for correct gear ratios for
commanded gears.
5. This step checks for low line pressure.
DTC P0730 Transmission Incorrect Gear Ratio
StepActionYe sNo
1Visually inspect the transmission cooling system for fluid leaks.

Refer to Chart 16: Possible Causes of Transmission Fluid
Leaks of Mechanical/Hydraulic Diagnosis Symptoms Index in
Automatic Transmission (4L30±E) section
Was condition found and corrected?
Go to Step 6Go to Step 2
2Refer to Checking Transmission Fluid Level and Condition in
Automatic Transmission (4L30±E) section.
Has transmission fluid checking procedure been performed?
Go to Step 3
Go to Checking
Transmission
Fluid Level and
Condition in
Automatic
Transmission
(4L30±E) section
31. Install the scan tool.
2. Turn the ignition switch to the ªonº position.
3. Engine not running.
NOTE: Before clearing DTC(s) use the scan tool to record the
ªFailure Recordsº for reference, as data will be lost when the ªClear
Infoº function is used.
4. Record the Failure Record data.
5. Use the scan tool snapshot mode to record transmission gear
ratios.
6. Drive vehicle in transmission gear ranges 1, 2, 3, and D with
the engine speed is greater than 3,500 rpm for 5.5 seconds.
7. Record each transmission gear.
1st:2.73 ± 2.99
2nd:1.54 ± 1.71
3rd:0.93 ± 1.05
4th:0.66 ± 0.78
Does commanded gear ratio match ranges as shown?
Refer to
Diagnostic Aids
Go to Step 4
4Perform line pressure check.

Refer to Line Pressure Test in Automatic Transmission
(4L30±E) section.
Was condition found and corrected?
Go to Step 6Go to Step 5

7A1±56
TRANSMISSION CONTROL SYSTEM (4L30±E)
DTC P0753 Shift Solenoid A Electrical
D07RW009
Circuit Description

The shift solenoid A is a simple on/off solenoid
located in the main case valve body. The solenoid is
the normally closed type. In second or third gear, the
Powertrain Control Module (PCM) energizes the
solenoid to open a fluid inlet port. When the port is
open, fluid pressure actuates the shift valve.

The solenoid is activated by current. This current is
produced by applying a voltage to one side (the High
side) and a ground to the other side (Low side).

The High Side Driver (HSD) is a circuit of the PCM
that acts as a switch between the solenoids and the
supply voltage. The High side of the solenoid is
permanently supplied with voltage, except in
BACKUP MODE or when ignition is off the HSD is
turned off.
This DTC detects a continuous open or short to ground in
the shift solenoid A circuit or the shift solenoid A. This is a
type ªCº DTC.
Conditions For Setting The DTC

Ignition is ªonº, Engine ªrunº.

Battery voltage is between 10 and 16 volts.

The PCM commands the solenoid ªonº and the
voltage remains high (B+) or the PCM commands the
solenoid ªoffº and the voltage remains low (zero
volts).

All conditions met for 0.33 seconds.
Action Taken When The DTC Sets

Maximum line pressure.

Immediate landing to 4th gear.

Inhibit TCC engagement.

The PCM will illuminate the CHECK TRANS Lamp.
Conditions For Clearing The MIL/DTC

The PCM will turn off the CHECK TRANS Lamp after
three consecutive ignition cycles without a failure
reported.

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

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

The PCM will cancel the DTC default actions when
the fault no longer exists and the ignition is cycled ªoffº
long enough to power down the PCM.
Diagnostic Aids

Inspect the wiring for poor electrical connection at the
PCM and at the transmission 16±way connector.
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.