1998 ISUZU TROOPER electrical system

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.

TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±55
DTC P0748 Pressure Control Solenoid (PCS) (Force Motor) Circuit Electrical
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. While the engine is operating, put the transmission in Park.
5. Using the scan tool, apply 0.1 amp through 1.0 amp while
observing ªPC Ref. Currentº and ªPC Act. Currentº.
Is the ªPC Act. Currentº reading always within 0.16 amp?
Go to Diagnostic
Aids
Go to Step 2
21. Turn the ignition ªoffº.
2. Disconnect the transmission 5±way connector M±6.
3. Using the J39200 DVOM, measure the resistance between
terminals M6±2(B) and M6±1(E).
Is the resistance within 3±7 ohms?
Go to Step 6Go to Step 3
31. Remove the transmission oil pan. Refer to Solenoid (Adapter
Case Valve Body) in Automatic Transmission (4L30±E)
section.
2. Disconnect the internal wiring harness at the PCS.
3. Measure the resistance of the PCS.
Is the resistance within 3±7 ohms?
Go to Step 5Go to Step 4
4Replace the PCS.
Is the replacement complete?
Go to Step 9Ð
5Repair the internal wiring harness for an open.
Is the repair complete?
Go to Step 9Ð
6Inspect/repair circuits J3±E4, M6±2(B), J3±E3, and M6±1(E).
Was a problem found?
Go to Step 9Go to Step 7
7Inspect/repair circuits J3±E4, M6±2(B), J3±E3, and M6±1(E) for
a short to ground or poor connections.
Was a problem found?
Go to Step 9Go to Step 8
8Replace the PCM. Refer to Powertrain Control Module (PCM) in
Automatic Transmission (4L30±E) section.
Is the replacement complete?
Go to Step 9Ð
91. After the repair is complete, use the scan tool to select ªDTCº,
then ªClear Infoº function and ensure the following conditions
are met:
The PCS duty cycle is not at its electrical high or low limit.
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

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

7A1±58
TRANSMISSION CONTROL SYSTEM (4L30±E)
DTC P0753 Shift Solenoid A Electrical (Cont'd)
StepNo Ye s Action
9Check every connection at the PCM connector.
Was a problem found?
Go to Step 17Go to Step 16
10The wiring harness between PCM connector terminals J3±F14
and transmission harness terminal M7±3(D) is shorted to voltage.
Was a problem found and corrected?
Go to Step 18Ð
11The wiring harness between PCM connector terminal
J3±F14 and transmission harness terminal M7±3(D) is shorted to
ground.
Was a problem found and corrected?
Go to Step 18Ð
12The wiring harness between PCM connector terminals J3±E14
and transmission harness terminal M7±4(C) is shorted to ground.
Was a problem found and corrected?
Go to Step 18Ð
13The wiring harness between PCM connector J3 and transmission
16±way connector H±53 is open or poor connection.
Was a problem found and corrected?
Go to Step 18Ð
14The wiring harness between transmission 16±way connector
H±53 and transmission main case connector M±7 is open or has a
poor connection.
Was a problem found and corrected?
Go to Step 18Ð
15The shift solenoid A is faulty.
Replace the shift solenoid A. Refer to Solenoid (Main Case Valve
Body) in Automatic Transmission (4L30±E) section.
Is the replacement complete?
Go to Step 18Ð
16The PCM may be faulty.
Replace the PCM. Refer to Powertrain Control Module (PCM) in
Automatic Transmission (4L30±E) section.
Is the replacement complete?
Go to Step 18Ð
17Repair the PCM connector connection.
Was a problem found and corrected?
Go to Step 18Ð
181. After the repair is complete, use the scan tool to select ªDTCº,
then ªClear Infoº function and operate the vehicle under the
following conditions:

The shift solenoid A is commanded ªonº and voltage drops to
zero.

The shift solenoid A is commanded ªoffº and voltage
increases to B+.
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±59
DTC P0758 Shift Solenoid B Electrical
D07RW009
Circuit Description

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

The solenoid is activated by current. This current is
procuded 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. In BACKUP
MODE or when the ignition is off, the HSD is turned
off.
This DTC detects a continuous open or short to ground in
the shift solenoid B circuit or shift solenoid B. 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

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

Inspect the wiring for poor electrical connections 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.

7A1±60
TRANSMISSION CONTROL SYSTEM (4L30±E)

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 char:
5. This test measures the resistance of the component.
7. This test checks the function of the shift solenoid B
and the transmission internal wiring harness.
11.This test checks for power to the shift solenoid B
from the ignition through the PCM.Shift Solenoid Status Chart
Gear
Shift solenoid AShift solenoid B
1stOFFON
2ndONON
3rdONOFF
4thOFFOFF
DTC P0758 Shift Solenoid B 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 3Go to Step 2
21. The engine ªonº.
2. Apply brake pedal and select transmission range ªDº.
3. Press and hold down the winter switch and select transmission
mode ªwinterº.
Does the scan tool display DTC P0758 at 3rd gear?
Go to Step 7
Go to Diagnostic
Aids
31. Turn the ignition ªoffº.
2. Disconnect the J2 (WHITE) and J3 (BLUE) PCM connectors.
3. Turn the ignition ªonº.
4. Using the J39200 DVOM, measure the voltage between PCM
connector terminals J2±C2 and J2±C8.
Is the voltage within 10 ± 12 volts?
Go to Step 14Go to Step 4
41. Turn the ignition ªoffº.
2. Using the J39200 DVOM, measure the resistance between
PCM connector terminals J2±C2 and J3±E14.
Is the resistance within 18 ± 20 ohms?
Go to Step 15Go to Step 5
51. Disconnect the transmission 16±way connector H±53.
2. Using the J39200 DVOM, measure the resistance between
terminals H53±16 and H53±15.
Is the resistance within 18 ± 20 ohms?
Go to Step 16Go to Step 6
61. Disconnect the transmission main case connector M±7.
2. Using the J39200 DVOM, measure the resistance between
terminals M7±1(A) and M7±4(C).
Is the resistance within 18 ± 20 ohms?
Go to Step 17Go to Step 18
71. Turn the ignition ªoffº.
2. Disconnect the J2 (WHITE) and J3 (BLUE) PCM connectors.
3. Using the J39200 DVOM, measure the resistance between
PCM connector terminals J2±C2 and J3±E14.
Is the resistance within 18 ± 20 ohms?
Go to Step 8Go to Step 9
8Using the J39200 DVOM, check a continuity between PCM
connector terminal J2±C2 and ground.
Is there a continuity?
Go to Step 19Go to Step 10

TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±61
DTC P0758 Shift Solenoid B Electrical (Cont'd)
StepNo Ye s Action
91. Disconnect the transmission 16±way connector H±53.
2. Using the J39200 DVOM, measure the resistance between
terminals H53±16 and H53±15.
Is the resistance within 18±20 ohms?
Go to Step 20Go to Step 11
10Using the J39200 DVOM, check a continuity between PCM
connector terminal J3±E14 and ground.
Is there a continuity?
Go to Step 21Go to Step 12
111. Disconnect the transmission main case connector M±7.
2. Using the J39200 DVOM, measure the resistance between
terminals M7±1(A) and M7±4(C).
Is the resistance within 18 ± 20 ohms?
Go to Step 22Go to Step 23
12Check every connection of the PCM and transmission 16±way
connector H±53.
Was a problem found and corrected?
Go to Step 25Go to Step 13
131. Connect the J2 (WHITE) and J3 (BLUE) PCM connectors to
the PCM.
2. Turn the ignition ªonº, the engine ªonº.
3. Repeat Step 3.
Does the scan tool display DTC P0758 at 3rd gear?
Go to Step 24
Go to Diagnostic
Aids
14The wiring harness between PCM connector terminal
J2±C2 and transmission main case terminal M7±1(A) is shorted
to voltage.
Was a problem found and corrected?
Go to Step 25Ð
15The PCM internal terminal J2±C2 is shorted to voltage.
Replace the PCM. Refer to Powertrain Control Module (PCM) in
Automatic Transmission (4L30±E) section.
Is the replacement complete?
Go to Step 25Ð
16The wiring harness between PCM connector and transmission
16±way connector is shorted.
Was a problem found and corrected?
Go to Step 25Ð
17The wiring harness between transmission 16±way connector and
transmission main case connector is shorted.
Was a problem found and corrected?
Go to Step 25Ð
18The shift solenoid B is faulty, or the internal wiring harness from
the shift solenoid B is shorted.
Was a problem found and corrected?
Go to Step 25Ð
19The wiring harness between PCM connector terminal
J2±C2 and transmission main case connector terminal M7±1(A)
is shorted to ground.
Was a problem found and corrected?
Go to Step 25Ð
20The wiring harness between PCM connector terminal J2±C2 and
transmission 16±way connector terminal H53±16, or between
PCM connector terminal J3±E14 and 16±way connector terminal
H53±15 is open.
Was a problem found and corrected?
Go to Step 25Ð