1998 ISUZU TROOPER check engine

7A1±34
TRANSMISSION CONTROL SYSTEM (4L30±E)
Diagnostic Aids

Refer to the accompanying chart for the normal range
signals and the illegal combinations.

Inspect the wiring for poor electrical connections at
the PCM and at the transmission 8±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.

Refer to the ªRange Switch Logic Tableº or
ªFunctional Test Procedureº for further information.
Test Description
The numbers below refer to the step numbers on the
diagnostic chart:
2. This test checks the indicated range signal to the
manual valve actually selected.5. This test checks for continuity between each
selected range switch connector terminals.
Range Switch Logic Table
Range
Range Switch Ping
PositionABCP(G)
ParkONOFFOFFON
ReverseONONOFFOFF
NeutralOFFONOFFON
D4OFFONONOFF
D3ONONONON
2ONOFFONOFF
LOFFOFFONON
IllegalOFFOFFOFFOFF
IllegalOFFOFFOFFON
DTC P0706 Transmission Range Switch (Mode Switch) Performance
StepActionYe sNo
1Perform the following checks:

The transmission linkage from the select lever to the manual
valve is adjusted properly.

Diagnostic circuit check.
Were the checks performed?
Go to Step 2Ð
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 ªFailure Recordsº.
4. Select each transmission range: D1, D2, D3, D4, N, R, and P.
Does each selected transmission range match the scan tool
ªRange Switchº display?
Go to Diagnostic
Aids
Go to Step 3
3Are all range switch pin displays incorrect?Go to Step 4Go to Step 5
4Check fuse and wiring to the 8±way connector terminal 5(D) for
opens.
Refer to Mode Switch in Automatic Transmission (4L30±E)
section.
If no problem was found, replace the range switch.
Is the replacement complete?
Go to Step 8Ð
51. Disconnect the 8±way range switch connector.
2. Using ohmmeter, check continuity between terminal 5(D) and
respectively terminals 3(G), 6(C), 7(B) and 8(A) of the 8±way
range switch connector.
3. Move shift selector lever through all positions and compare
results with ªRange Switch Logic Tableº.
Is one range switch pin display incorrect?
Go to Step 6Go to Step 7
6Check the affected wiring and connector, and repair.
Is the repair complete?
Go to Step 8Ð

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

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±43
DTC P0719 TCC Brake Switch Circuit High (Stuck On)
StepActionYe sNo
11. Install the scan tool.
2. With the engine ªoffº, turn the ignition switch ªonº. If ABS code
is set, check applicable fuse.
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 ªFailure Recordsº.
4. Apply then release the brake pedal.
Does the scan tool display ªTCC Brake Switchº as ªclosedº with
the brake pedal applied, and then display ªopenº when the brake
pedal is released?
Go to Diagnostic
Aids
Go to Step 2
21. Connect the test light to ground.
2. Back probe ignition feed circuit terminal B13±1 at the brake
switch.
Is the test light ªonº?
Go to Step 3Go to Step 4
31. Connect the test light to ground.
2. Back probe circuit terminal B13±4 at the brake switch.
Is the test light ªoffº?
Go to Step 7Go to Step 5
4Repair the open in battery feed circuit terminal B13±1 to the brake
switch.
If fuse is open, check circuit terminal B13±4 for a short to ground.
Is the repair complete?
Go to Step 13Ð
5Disconnect brake switch connector B±13 and ignition switch ªonº.
Is the test light ªonº?
Go to Step 8Go to Step 6
6Check the brake switch short (B13±1 and B13±4).
Was a problem found?
Go to Step 9Go to Step 10
7Check circuit terminal B13±4 for a short to voltage.
Ignition switch ªonº.
Is the test light ªonº?
Go to Step 8Go to Step 10
81. Disconnect the J3 (BLUE) PCM connector.
2. Check circuit terminal B13±4 for a short to voltage.
Was a problem found?
Go to Step 13Go to Step 10
9Replace the brake switch.
Is the replacement complete?
Go to Step 13Ð
101. Turn the ignition ªoffº.
2. Reconnect the J3 (BLUE) PCM connector.
3. Turn the ignition ªonº.
Does the scan tool display ªTCC Brake Switchº as ªopenº with the
brake applied, then display ªclosedº with the brake pedal
released?
Go to Diagnostic
Aids
Go to Step 11
11Check the PCM for faulty or intermittent connections.
Was a problem found and corrected?
Go to Step 13Go to Step 12

TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±45
DTC P0722 Transmission Output Speed Sensor (OSS) Low Input
D07RW006
Circuit Description
Output speed information is provided to the PCM by the
OSS, which is a permanent magnet (PM) generator. The
PM generator produces a pulsing AC voltage. The AC
voltage level and number of pulses increases as the
speed of the vehicle increases. The PCM then converts
the pulsing voltage to output speed, which is used for
calculations. The vehicle speed can be displayed with a
scan tool.
This DTC detects a low output speed when there is a high
engine speed in a drive gear range. This is a type ªCº
DTC.
Conditions For Setting The DTC

No MAP DTCs P0107 or P0108, P0106, P1106,
P1107.

No TPS DTCs P0122 or P0123.

Not in Park or Neutral.

TP angle is greater than 10%.

Engine vacuum is between 0 and 70kPa.

Engine speed is between 3,000 and 7,000 rpm.

Transmission output speed is less than 0 rpm.

All conditions met for 5 seconds.
Action Taken When The DTC Sets

Fixed to 4th gear.

Maximum line pressure.

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

An OSS DTC P0722 will set when no output speed is
at detected at start off.

Inspect the wiring for poor electrical connection at the
PCM. 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.
Test Description
The numbers below refer to the step numbers on the
diagnostic chart:
5. This test checks the OSS circuit.
6. This test checks the integrity of the OSS.
8. This test checks the 5±volt and ground circuit of the
PCM.

7A1±46
TRANSMISSION CONTROL SYSTEM (4L30±E)
DTC P0722 Transmission Output Speed Sensor (OSS) Low Input
StepActionYe sNo
11. 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 ªFailure Recordsº.
4. Raise the drive wheels.
5. Start the engine.
6. Place the transmission in any drive range.
With the drive wheels rotating, does the ªTrans Output Speedº
increase with the drive wheel speed?
Go to Diagnostic
Aids
Go to Step 2
2Does the speedometer work?Go to Step 3Go to Step 4
3Check for the most current and/or incorrect calibration.
Is the calibration current?
Go to Step 16Go to Step 4
41. Turn the ignition ªoffº.
2. Disconnect the J3 (BLUE) PCM connector.
3. Using the J39200 DVOM, measure the resistance between
harness connector terminals J3±E1 and J3±E2.
Is the reading 3,000 ohms?
Go to Step 5Go to Step 6
51. Select AC volts.
2. Rotate the rear wheels, ensuring the driveshaft is turning.
Is the voltage greater than 0.5 volts?
Go to Step 7Go to Step 8
6Inspect circuits RED and WHT for a poor connection or an open
circuit.
Was a problem found?
Go to Step 17Go to Step 8
71. Reconnect the J3 (BLUE) PCM connector.
2. Disconnect the OSS harness from the OSS.
3. With the engine ªoffº, turn the ignition ªonº.
4. Using the J 39200 DVOM, measure the voltage at the OSS
harness connector terminals M15±1 and M15±2.
Is the reading between 4.0 to 5.1 volts?
Go to Step 16Go to Step 10
81. Remove the OSS.
2. Check the output shaft speed sensor rotor for damage or
misalignment. Refer to Speed Sensor (Extension Housing) in
Automatic Transmission (4L30±E) section.
Was a problem found?
Go to Step 17Go to Step 9
9Replace the OSS.
Is the replacement complete?
Go to Step 17Ð
10Was the reading in step 8 less than 4.0 volts?Go to Step 12Go to Step 11
11Was the reading in Step 8 greater than 5.1 volts?Go to Step 15Ð
12Using the J 39200 DVOM to chassis ground, measure the voltage
on circuit RED.
Is the reading between 4.0 to 5.1 volts?
Go to Step 13Go to Step 14
13Repair the open in circuit WHT.
Is the repair complete?
Go to Step 17Ð
14Check circuit RED for a short to ground or open.
Was a problem found and corrected?
Go to Step 17Go to Step 16