check engine ISUZU TROOPER 1998 Service Repair Manual

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

TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±63
DTC P1790 ROM Transmission Side
Bad Check Sum
Circuit Description
Transmission Side Read Only Memory (ROM) and
Electronically Erasable Programmable Read Only
Memory (EEPROM) is an electronic circuit that controls
the transmission control in the Powertrain Control Module
(PCM).
This DTC detects a check sum error. This is a type ªCº
DTC.
Conditions For Setting The DTC

Detects check sum error for 1 second.
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.
DTC P1790 ROM Transmission Side Bad Check Sum
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.
Was DTC P1790 set?
Go to Step 4Go to Step 2
2Was DTC P1792 set?Go to Step 3Ð
31. Remove the PCM. Refer to Powertrain Control Module (PCM)
in Automatic Transmission (4L30±E) section.
2. Using the ITCS, make a reprogramming the transmission
EEPROM.
Was the reprogramming complete?
Go to Step 5Ð
4Replace the PCM.
Is the replacement complete?
Go to Step 5Ð
51. After the repair is complete, use the scan tool to select ªDTCº,
then ªClear Infoº function and operate the vehicle.
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±64
TRANSMISSION CONTROL SYSTEM (4L30±E)
DTC P1792 EEPROM Transmission
Side Bad Check Sum
Circuit Description
Transmission Side Read Only Memory (ROM) and
Electronically Erasable Programmable Read Only
Memory (EEPROM) is an electronic circuit that controls
the transmission control in the Powertrain Control Module
(PCM).
This DTC detects a check sum error. This is a type ªCº
DTC.
Conditions For Setting The DTC

Detects check sum error for 1 second.
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.
DTC P1792 EEPROM Transmission Side Check Bad Check Sum
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.
Was DTC P1790 set?
Go to Step 4Go to Step 2
2Was DTC P1792 set?Go to Step 3Ð
31. Remove the PCM. Refer to Powertrain Control Module (PCM)
in Automatic Transmission (4L30±E) section.
2. Using the ITCS, make a reprogramming the transmission
EEPROM.
Was the reprogramming complete?
Go to Step 5Ð
4Replace the PCM.
Is the replacement complete?
Go to Step 5Ð
51. After the repair is complete, use the scan tool to select ªDTCº,
then ªClear Infoº function and operate the vehicle.
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±65
DTC P1835 Kickdown Switch Always On
D07RW033
Circuit Description

When the driver presses the accelerator pedal down
fully, the kickdown switch closes, sending a ground
signal to the Powertrain Control Module (PCM).

This information is used to perform shifts at high
engine speed.

When the kickdown switch is closed, the Throttle
Position Sensor (TPS) is already is at 100%.

This DTC detects a closed kickdown switch when TP
angle is less than 70%.

This is a type ªDº DTC.
Conditions For Setting The DTC

No TPS DTCs P0122 or P0123.

TP angle is less than 70%.

Kickdown switch is ªonº.

All conditions met for 1 second.
Action Taken When The DTC Sets.

Kickdown mode control is off.

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 the wiring harness for a short to ground
between the PCM and kickdown switch.

Check the kickdown switch for failure.

Check kickdown adjustment.
Test Description
The numbers below refer to the step numbers on the
diagnostic chart:
2. This test checks for short to ground or kickdown
switch failure.
4. This test checks for regulation kickdown switch.

7A1±66
TRANSMISSION CONTROL SYSTEM (4L30±E)
DTC P1835 Kickdown Switch Always On
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.
Does the scan tool display ªKickdown switchº ªlowº (closed
switch)?
Go to Step 2Go to Step 3
21. Turn the ignition ªoffº.
2. Disconnect the J3 (BLUE) PCM connector.
3. Using the J39200 DVOM, check a continuity between PCM
connector terminal J3±F11 and ground.
Is there a continuity?
Go to Step 4Go to Step 7
3The TP angle goes from 0% to 100% with the accelerator pedal
depressed.
Is the kickdown switch ªonº when TP angle is below 70%?
Go to Step 5
Go to Diagnostic
Aids
41. Disconnect the kickdown switch connector B±10.
2. Using the J39200 DVOM, check a continuity between
terminals B10±1 and B10±2.
Is there a continuity?
Go to Step 6Go to Step 8
5Adjust the kickdown switch.
Is the kickdown switch ªonº when TP angle is above 95%?
Go to Step 9Ð
6Replace the kickdown switch.
Is the replacement complete?
Go to Step 9Ð
7Replace the PCM. Refer to Powertrain Control Module (PCM) in
Automatic Transmission (4L30±E) section.
Is the replacement complete?
Go to Step 9Ð
8Repair the short to ground in circuit LT BLUE.
Is the repair 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 condition is
met:
The torque converter stator temperature switch circuit does not
indicate a hot mode when the transmission fluid temperature is
less than 60
C (140
F) for at least 5 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±67
DTC P1850 Brake Band Apply Solenoid Malfunction
D07RW009
Circuit Description

The brake band apply solenoid is a normally open
solenoid which controls the flow of fluid for brake band
application. The Powertrain Control Module (PCM)
uses Pulse Width Modulation (PWM) and changes
the duty cycle to control the solenoid. The PCM turns
the solenoid on (energized) and off (deenergized) at a
constant frequency. The length of time the solenoid is
energized during each on/off cycle is called the pulse
width. By varying or ªmodulatingº the pulse width, the
solenoid output pressure is changed. Since the
solenoid is normally open, increasing the pulse width
increases the duty cycle and decreases the output
pressure. PWM control provides smooth band
application without an accumulator. The band is only
applied in first and second gears.

In the event of an electrical failure (open), the
solenoid regulates at the maximum oil flow (0% duty
cycle).

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. When the ignition
is off, the HSD is turned off.This DTC detects a continuous open or short to ground in
the brake band apply solenoid circuit or the brake band
apply solenoid. This is a type ªDº DTC.
Conditions For Setting The DTC

Battery voltage is between 10 and 16 volts.

Ignition is ªonº, Engine ªrunº.

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 in 1.3 seconds.
Action Taken When The DTC Sets

Inhibit brake band apply solenoid.

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.

7A1±68
TRANSMISSION CONTROL SYSTEM (4L30±E)
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.
Test Description
The numbers below refer to the step numbers on the
diagnostic chart:
3. This test checks for power to the brake band apply
solenoid from the ignition through the PCM.
4. This test checks the resistance of the transmission
internal wiring harness and brake band apply
solenoid.
5. This test checks the ability of the PCM and wiring to
control the ground circuit.
DTC P1850 Brake Band Apply Solenoid Malfunction
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 set?
Go to Step 2Go to Step 3
2Using the J39200 DVOM, back probe between PCM connector
terminals J3±E14 and J2±C8.
Is the voltage between 10 to 12 volts?
Go to Step 4Go to Step 5
31. Turn the ignition ªoffº.
2. Disconnect the J1 (RED) and J3 (BLUE) PCM connectors.
3. Using the J39200 DVOM, measure the resistance between
PCM connector terminals J1±A16 and J3±E14.
Is the resistance within 10±12 ohms?
Go to Step 11Go to Step 12
4Using the J39200 DVOM, back probe between PCM connector
terminals J1±A16 and J2±C8.
Is the voltage between 10 to 12 volts?
Go to Step 25Go to Step 3
51. Turn the ignition ªoffº.
2. Disconnect the J1 (RED) and J3 (BLUE) PCM connectors.
3. Using the J39200 DVOM, check continuity between PCM
terminal J3±E14 and ground.
Is there a continuity?
Go to Step 6Go to Step 8
61. Disconnect the transmission 16±way connector H±53.
2. Using the J39200 DVOM, check continuity between connector
H53±13 and ground.
Is there a continuity?
Go to Step 7Go to Step 16
71. Disconnect the transmission main case connector M±7.
2. Using the J39200 DVOM, check continuity between the
terminal M7±2(B) and ground.
Is there a continuity?
Go to Step 17Go to Step 18
81. Disconnect the J1 (RED) PCM Connector.
2. Using the J39200 DVOM, measure the resistance between
PCM connector terminals J1±A16 and J3±E14.
Is the resistance within 10±12 ohms?
Go to Step 25Go to Step 9
91. Disconnect the transmission 16±way connector H±53.
2. Using the J39200 DVOM, measure the resistance between
terminal H53±13 and H53±15.
Is the resistance within 10±12 ohms?
Go to Step 16Go to Step 10

TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±71
DTC P1860 TCC Solenoid Electrical
D07RW010
Circuit Description
The PCM allows current to flow through the solenoid coil
according to the duty cycle (percentage of ªonº and ªoffº
time). This current flow through the solenoid coil creates
a magnetic field that magnetizes the solid core. The
magnetized core attracts the check ball to seat against
spring pressure. This blocks the exhaust for the TCC
signal fluid and allows 2±3 drive fluid to feed to TCC signal
circuit. The TCC signal fluid pressure acts on the TCC
regulator valve to regulate line pressure and to apply fluid
pressure to the torque converter clutch shift valve. When
the TCC shift valve is in the apply position, regulated
apply fluid pressure is directed through the TCC valve to
apply the torque converter clutch. The TCC solenoid is
used in conjunction with the TCC solenoid to regulate fluid
to the torque converter. The TCC solenoid is attached to
the valve body within the transmission.
This DTC detects a continuous open or short to ground or
ignition in the TCC circuit or the TCC solenoid. This is a
type ªDº DTC.
Conditions For Setting The DTC

Battery voltage is between 10 and 16 volts.

No shift solenoid A DTC P0753.

No shift solenoid B DTC P0758.

Ignition is ªonº, Engine ªrunº.

The PCM commands the solenoid ªonº and the
voltage remains low (zero volts).

The PCM commands the solenoid ªoffº and the
voltage remains high (B+).

All conditions met for 0.25 seconds.
Action Taken When The DTC Sets

Inhibit TCC engagement.
The PCM will not illuminate the CHECK TRANS
Lamp.
Conditions For Clearing The MIL/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 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.

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:
3. This test checks for voltage to the solenoid.
4. This test checks the ability of the PCM and wiring to
control the ignition circuit.
9. This test checks the resistance of the TCC solenoid
and the internal wiring harness.