Isuzu Trooper (1998-2002 year). Service manual — part 621

6E–132

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P1404 (Flash DTC 31)

EGR VSV Circuit

060RW135

Circuit Description

The Engine control module (ECM) monitors the EGR
valve input to ensure that the valve responds properly to
commands from the ECM, and to detect a fault if VSV is
stuck open. When the VSV is fixing at closed and opening
the ECM will set DTC P1404.

Diagnostic Aids

Check for the following conditions:

D

Poor connection or damaged VSV–inspect the wiring
harness for damage.

DTC P1404 – EGR VSV Circuit

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to

Step 2

Go to

OBD

System

Check

2

1. Ignition “ON”, engine “OFF”, review and record

scan tool Failure Records data.

2. Operate the vehicle within Failure Records

conditions as noted.

3. Using a scan tool, monitor “Specific DTC” info for

DTC P1404 until the DTC P1404 test runs. Note the
result.

Does the scan tool indicates DTC P1404 failed this
ignition?

—

Go to

Step 3

Refer to

Diagnostic

Aids

6E–133

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

DTC P1404 – EGR VSV Circuit

(Cont'd)

Step

No

Yes

Value(s)

Action

3

Check the VSV circuit.

Was the VSV circuit open or darmage?

—

Go to

Step 4

Go to

Step 5

4

Repair the opened VSV circuit or VSV.

Is the action complete?

—

Verify repair

—

6E–134

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0405 (Flash DTC 26)

EGR Pressure Sensor Low Voltage

060RW134

Action Taken When the DTC Sets

D

The ECM will illuminate the malfunction indicator lamp
(MIL) as soon as failure detected.

D

The ECM will store conditions which were present
when the DTC was set as Freeze Frame and in Failure
Records data.

Conditions for Clearing the MIL/DTC

D

DTC P0405 can be cleared by using the scan tool
“Clear Info” function or by disconnecting the ECM
battery feed.

Diagnostic Aids

Check for the following conditions:

D

Poor connection or damaged harness – Inspect the
wiring harness for damage.

DTC P0405 – EGR Pressure Sensor Low Voltage

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to

Step 2

Go to

OBD

System

Check

2

Put the engine into an idling status.

Is the EGR pressure sensor voltage value displayed on
the Tech 2 below the specified value?

0.25 V

Go to

Step 3

Refer to

Diagnostic

AidsandSymp

tom

Diagnosis

6E–135

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

DTC P0405 – EGR Pressure Sensor Low Voltage

(Cont'd)

Step

No

Yes

Value(s)

Action

3

1. Turn off the ignition switch.
2. Remove the sensor connector connection.
3. Jumper between harness pins “red” and “blue”

wires.

4. Turn on the ignition switch “ON”.

Is the EGR pressure sensor voltage reading above the
specified value?

4 V

Go to

Step 5

Go to

Step 4

4

1. Turn off the ignition switch.
2. Remove the jumper wire.
3. Connect the relay & solenoid checker

(5-8840-0386-0) to the battery voltage, then check
the EGR pressure sensor signal circuit (blue wire).

4. Turn on the ignition switch.

Is the value displayed on the Tech 2 above the specified
value?

4 V

Go to

Step 6

Go to

Step 7

5

Check the terminal connection at the EGR pressure
sensor and repair or replace terminal if necessary.

Is the action complete?

—

Verify repair

—

6

Repair the 5V power circuit (red) harness or Replace
the ECM (Refer to the Data Programming in Case of
ECM change).

Is the action complete?

—

Verify repair

—

7

Repair the signal circuit (blue) harness or Replace the
ECM (Refer to the Data Programming in Case of ECM
change).

Is the action complete?

—

Verify repair

—