1998 ISUZU TROOPER check engine

7A1±48
TRANSMISSION CONTROL SYSTEM (4L30±E)
DTC P0723 Transmission Output Speed Sensor (OSS) Intermittent
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
In Park or Neutral:

Transmission output speed change is greater than
10,000 rpm.

Conditions met for 6 seconds.

Engine running time is greater than 2 seconds.
Not in Park or Neutral:

Transmission output speed change is greater than
512 rpm.

Conditions met for 0.075 seconds

Engine running time is greater than 2 seconds.

Engine vacuum is less than 70 kPa.

Output speed is greater than 1,380 rpm for 1 second.

NORAW±NOLAST < 60 rpm for 6 seconds.
NORAW: Latest raw data of output shaft speed.
NOLAST: Filtered pervious data of output speed.
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

A OSS DTC P0723 will set when output speed has
been detected and is lost.

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.

TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±49
DTC P0723 Transmission Output Speed Sensor (OSS) Intermittent
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

TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±51
DTC P0730 Transmission Incorrect Gear Ratio
D07RT015
Circuit Description

The Powertrain Control Module (PCM) calculates the
slippage of the converter and transmission based
upon the engine speed, the output speed, and the
current gear ratio.

The slippage of the converter at a high enough engine
speed is low. The transmission should not slip more
than a given value when there is no shift.

This DTC detects a slip at each gear. This is a type
ªCº DTC.
Conditions For Setting The DTC

No Output Speed Sensor DTC(s) P0722, P0723.

Not in Park, Neutral, or Reverse.

Engine speed is greater than 3,500 rpm.
3 seconds since upshift.

3 seconds since downshift.

3 seconds since garage shift (N"D).

And one of the following conditions occur:
± Slip is greater than 508 rpm in 1st gear.
± Slip is greater than 468 rpm in 2nd gear.
± Slip is greater than 449 rpm on 3rd gear.
± Slip is greater than 440 rpm on 4th gear.

All conditions met for 5.5 seconds.Action Taken When The DTC Sets

Maximum line pressure.

The PCM will illuminate the CHECK TRANS Lamp.

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

TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±53
DTC P0730 Transmission Incorrect Gear Ratio (Cont'd)
StepNo Ye s Action
5Check for possible clutch slippage.

Refer to Chart 6: Diagnostic Trouble Code (DTC) P0730 of
Mechanical/Hydraulic Diagnosis Symptoms Index in
Automatic Transmission (4L30±E) section.
Was condition found and corrected?
Go to Step 6Ð
61. After the repair is complete, use the scan tool to select ªDTCº,
then ªClear infoº function.
2. Operate the vehicle under the following conditions:

Drive the vehicle in D4 with the engine speed greater than
3,500 rpm to obtain anyone of the following gear ratios for
seven seconds.
1st 1:2.73 ± 1:2.99
2nd 1:1.54 ± 1:1.71
3rd 1:0.93 ± 1:1.05
4th 1:0.66 ± 1:0.78
Has the last test failed?
Begin diagnosis
again
Go to Step 1
Repair verified
Exit DTC table

7A1±54
TRANSMISSION CONTROL SYSTEM (4L30±E)
DTC P0748 Pressure Control Solenoid (PCS) (Force Motor) Circuit Electrical
D07RW008
Circuit Description
The PCS is a PCM±controlled device used to regulate
transmission line pressure. The PCM compares TPS
voltage, engine rpm, and other inputs to determine the
line pressure appropriate for a given load. The PCM will
regulate the pressure by applying a varying amperage to
the PCS. The applied amperage can vary from 0.1 to 1
amp, and is monitored by the PCM.
This DTC detects a continuous open or short to ground in
the PCS circuit or the PCS. This is a type ªCº DTC.
Conditions For Setting The DTC

Battery voltage is between 10 and 16 volts.

The PCM detects that the different between
commanded and actual current is 200 milliampere
(mA) for over 1 second.
Action Taken When the DTC Sets

Maximum line pressure.

The PCM will illuminate the CHECK TRANS Lamp.
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 history by using a
scan tool.
The DTC will be cleared from memory 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 5±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.
Test Description
The numbers below refer to the step numbers on the
diagnostic chart:
2. This test checks the ability of the PCM to command
the PCS.
3. This test checks the PCS and internal wiring harness
for incorrect resistance.

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.

TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±57

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

An open ignition feed circuit can cause multiple DTCs
to set.
Test Description
The numbers below refer to the step numbers on the
diagnostic chart:
3. This test checks for power to the shift solenoid A
from the ignition through the PCM.
5. This test measures the resistance of the component.9. This test checks the function of the shift solenoid A
and the transmission internal wiring harness.
Shift Solenoid Status Chart
Gear
Shift solenoid AShift solenoid B
1stOFFON
2ndONON
3rdONOFF
4thOFFOFF
DTC P0753 Shift Solenoid A Electrical
StepActionYe sNo
11. Install the scan tool.
2. With the engine ªonº, 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.
Were DTCs P0753, P0758, P1860 set?
Go to Step 2
Go to Diagnostic
Aids
21. Turn the ignition ªonº.
2. Using the J39200 DVOM, measure the voltage between PCM
connector terminals J3±E14 and J2±C8 (GND).
Is the voltage within 10±12 volts?
Go to Step 3Go to Step 4
31. Turn the ignition ªoffº.
2. Disconnect the J3 (BLUE) PCM connector.
3. Turn the ignition ªonº.
4. Using the J39200 DVOM, measure the voltage between PCM
connector terminals J3±F14 and ground.
Is the voltage within 10 ± 12 volts?
Go to Step 10Go to Step 4
41. Turn the ignition ªoffº.
2. Disconnect the J3 (BLUE) PCM connector.
3. Using the J39200 DVOM, measure the resistance between
PCM connector terminals J3±E14 and J3±F14.
Is the resistance within 18 ± 20 ohms?
Go to Step 5Go to Step 6
51. Disconnect the J1 (RED) and J2 (WHITE) PCM connectors.
2. Using the J39200 DVOM, check a continuity between PCM
terminals J3±F14 and ground.
Is there a continuity?
Go to Step 11Go to Step 7
61. Disconnect the 16±way harness connector H±53.
2. Using the J39200 DVOM, measure the resistance between
terminals H53±14 and H53±15.
Is the resistance within 18±20 ohms?
Go to Step 13Go to Step 8
7Using the J39200 DVOM, check a continuity between J3 (BLUE)
PCM terminal E14 and ground.
Is there a continuity?
Go to Step 12Go to Step 9
81. Disconnect the transmission main case 4 pin connector M±7.
2. Using the J39200 DVOM, measure the resistance between
terminals M7±3(D) and M7±4(C).
Is the resistance within 18±20 ohms?
Go to Step 14Go to Step 15