Isuzu KB P190. Manual - part 446

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-167

4

1.

Remove the EGR valve assembly from the
engine.

2.

Inspect the EGR valve for the following
conditions:

• Restricted EGR valve by foreign

materials

• Excessive deposits at valve

• Bent valve shaft

3.

Repair or replace as necessary.

Did you find and correct the condition?

—

Go to Step 7

Go to Step 5

5

1.

Turn OFF the ignition.

2.

Disconnect the EGR valve harness connector.

3.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the EGR valve (pins 1, 2, 3, 4
and 6 of E-71).

4.

Disconnect the ECM harness connector.

5.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the ECM (pins 30, 31, 32, 62 and
63 of E-90).

6.

Test for high resistance on each circuit.

7.

Repair the connection(s) or circuit(s) as
necessary.

Did you find and correct the condition?

—

Go to Step 7

Go to Step 6

6

Replace the EGR valve. Refer to EGR Valve
Replacement.

Did you complete the replacement?

—

Go to Step 7

—

7

1.

Reconnect all previously disconnected
harness connector(s).

2.

Clear the DTCs with a scan tool.

3.

Turn OFF the ignition for 30 seconds.

4.

Start the engine.

5.

Operate the vehicle within the Conditions for
Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.

Did the DTC fail this ignition?

—

Go to Step 2

Go to Step 8

8

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

—

Go to DTC List

System OK

Step

Action

Value(s)

Yes

No

6E-168   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

DTC P0405 or P0406 (Flash Code 44)

Circuit Description

The exhaust gas recirculation (EGR) position sensor is
installed on the EGR valve body together with the
control solenoid. The EGR position sensor changes
output voltage according to EGR valve position. The
sensor has the following circuits.

• 5 volts reference circuit

• Low reference circuit

• EGR position sensor signal circuit

The EGR position sensor provides a signal to the ECM
on the signal circuit, which is relative to the position
changes of the EGR valve. If the ECM detects an
excessively low or high signal voltage, DTC P0405 or
P0406 will set.

Condition for Running the DTC

• DTCs P0652 and P0653 are not set.

• The battery voltage is more than 9 volts.

• The ignition switch is ON.

Condition for Setting the DTC

• The ECM detects that the EGR position sensor

signal voltage is less than 0.2 volts for 3 seconds.
(DTC P0405)

• The ECM detects that the EGR position sensor

signal voltage is more than 4.6 volts for 3 seconds.
(DTC P0406)

Action Taken When the DTC Sets

• The ECM illuminates the MIL on the second

consecutive driving cycle when the diagnostic runs
and fails. Refer to DTC Type Definitions for Action
Taken When the DTC Sets - Type B. (Euro 4
Specification)

• The ECM illuminates the MIL when the diagnostic

runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
(Except Euro 4 Specification)

• The ECM inhibits EGR control.

• The ECM inhibits cruise control.

Condition for Clearing the DTC

• Refer to DTC Type Definitions for Condition for

Clearing the MIL/ DTC - Type B. (Euro 4
Specification)

• Refer to DTC Type Definitions for Condition for

Clearing the MIL/ DTC - Type A. (Except Euro 4
Specification)

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views

Circuit/ System Testing DTC P0405

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check -
Engine Controls?

—

Go to Step 2

Go to Diagnostic 

System Check - 
Engine Controls

2

1.

Install a scan tool.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Monitor the DTC Information with a scan tool.

Is DTC P0652 also set?

—

Go to DTC P0652

Go to Step 3

3

Observe the EGR Position Sensor parameter with
a scan tool.

Is EGR Position Sensor parameter less than the
specified value?

0.2 volts

Go to Step 4

Go to Diagnostic 

Aids

4

1.

Turn OFF the ignition.

2.

Disconnect the EGR valve harness connector.

3.

Connect a DMM between the 5 volts reference
circuit (pin 1 of E-71) and a known good
ground.

4.

Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified value?

4.7 volts

Go to Step 5

Go to Step 6

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-169

5

Connect a 3-amp fused jumper wire between the 5
volts reference circuit and the signal circuit (pins 1
and 3 of E-71).

Is the EGR Position Sensor parameter more than
the specified value?

4.7 volts

Go to Step 8

Go to Step 7

6

1.

Test the 5 volts reference circuit between the
ECM (pin 31 of E-90) and the EGR valve (pin
1 of E-71) for an open circuit or high
resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 9

7

1.

Test the signal circuit between the ECM (pin
32 of E-90) and the EGR valve (pin 3 for E-71)
for the following conditions:

• An open circuit

• A short to ground

• A short to the low reference circuit

• High resistance

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 9

8

1.

Inspect for an intermittent and for poor
connections at the harness connector of the
EGR valve (pins 1 and 3 of E-71).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 10

9

1.

Turn OFF the ignition.

2.

Disconnect the ECM harness connector.

3.

Inspect for an intermittent and for poor
connections at the harness connector of the
ECM (pins 31 and 32 of E-90).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 11

10

Replace the EGR valve. Refer to EGR Valve
Replacement.

Did you complete the replacement?

—

Go to Step 12

—

11

Important: Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.

Did you complete the replacement?

—

Go to Step 12

—

12

1.

Reconnect all previously disconnected
harness connector(s).

2.

Clear the DTCs with a scan tool.

3.

Turn OFF the ignition for 30 seconds.

4.

Start the engine.

5.

Operate the vehicle within the Conditions for
Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 13

Step

Action

Value(s)

Yes

No

6E-170   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Circuit/ System Testing DTC P0406

13

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

—

Go to DTC List

System OK

Step

Action

Value(s)

Yes

No

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check -
Engine Controls?

—

Go to Step 2

Go to Diagnostic 

System Check - 
Engine Controls

2

1.

Install a scan tool.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Observe the EGR Position Sensor parameter
with a scan tool.

Is the EGR Position Sensor parameter more than
the specified valve?

4.6 volts

Go to Step 3

Go to Diagnostic 

Aids

3

Monitor the DTC Information with a scan tool.

Is DTC P0653 also set?

—

Go to Step 4

Go to Step 5

4

1.

Turn OFF the ignition.

2.

Disconnect the EGR valve harness connector.

3.

Turn ON the ignition, with the engine OFF.

Is the EGR Position Sensor parameter less than
the specified value?

0.1 volts

Go to DTC P0653

Go to Step 7

5

1.

Turn OFF the ignition.

2.

Disconnect the EGR valve harness connector.

3.

Turn ON the ignition, with the engine OFF.

Is the EGR Position Sensor parameter less than
the specified value?

0.1 volts

Go to Step 6

Go to Step 7

6

Connect a test lamp between the low reference
circuit (pin 2 of E-71) and battery voltage.

Does the test lamp illuminate?

—

Go to Step 9

Go to Step 8

7

Important: The EGR position sensor may be
damaged if the sensor signal circuit is shorted to a
voltage source.

1.

Test the signal circuit between the ECM (pin
32 of E-90) and the EGR valve (pin 3 of E-71)
for the following conditions:

• A short to battery or ignition voltage

• A short to any 5 volts reference

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 12

8

1.

Test the low reference circuit between the
ECM (pin 30 of E-90) and the EGR valve (pin
2 of E-71) for an open circuit or high
resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 10