Isuzu N-Series. Manual - part 689

6E-178    Engine Control System (4HK1) 

5

1.

Turn OFF the ignition.

2.

Connect a 3-amp fused jumper wire between
the 5 volts reference circuit and the signal
circuit of the EGR valve position sensor
harness (pins 1 and 3 of E-94 connector).

3.

Turn ON the ignition, with the engine OFF.

4.

Observe the EGR Position Sensor parameter
with the Tech 2.

Is the EGR Position Sensor parameter more than
specified value?

4.5 volts

Go to Step 8

Go to Step 7

6

1.

Test the 5 volts reference circuit between the
engine control module (ECM) (pin 87 of E-111
connector) and the EGR valve position sensor
(pin 1 of E-94 connector) 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
86 of E-111 connector) and the EGR valve
position sensor (pin 3 of E-94 connector) 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.

Turn OFF the ignition.

2.

Disconnect the EGR valve harness connector.

3.

Inspect for an intermittent and for poor
connections at the harness connector of the
EGR valve (pins 1 and 3 of E-94 connector).

4.

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 on the EGR valve position sensor
circuits at the harness connector of the ECM
(pins 86 and 87 of E-111 connector).

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 in this section. (EGR valve position
sensor is internal to EGR valve)

Did you complete the replacement?

—

Go to Step 12

—

11

Important:
Replacement ECM must be programmed.

Replace the ECM. Refer to Engine Control Module
(ECM) Replacement / Fuel Injector ID Code Data
Programming in this section.

Did you complete the replacement?

—

Go to Step 12

—

Step

Action

Value(s)

Yes

No

 Engine Control System (4HK1)    6E-179

12

1.

Reconnect all previously disconnected
harness connector(s).

2.

Clear the DTCs with the Tech 2.

3.

Turn OFF the ignition for 30 seconds.

4.

Start the engine.

5.

Operate the vehicle within the Conditions for
Running the DTC.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 13

13

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic 

Trouble Code (DTC) 

List

System OK

Step

Action

Value(s)

Yes

No

6E-180    Engine Control System (4HK1) 

P0486 (Flash Code 44)

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

• 5 volts reference circuit
• Low reference circuit
• EGR valve position sensor signal circuit

The engine control module (ECM) supplies 5 volts to
the EGR valve position sensor on the 5 volts reference
circuit. The ECM also provides a ground on the low
reference circuit. The EGR valve position sensor
provides a signal to the ECM on the EGR valve position
signal circuit, which is relative to the position changes
of the EGR valve. The ECM monitors the EGR position
sensor signals for voltage outside the normal range of
the EGR position. If the ECM detects an excessively
high EGR valve position signal voltage, this DTC will
set.

Condition for Running the DTC

• DTCs P1630 and P1635 are not set.
• The ignition switch is ON.
• The ignition voltage is more than 18 volts.

Condition for Setting the DTC

• The ECM detects that the EGR valve position

sensor signal voltage is more than 4.9 volts for 5
seconds.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM inhibits EGR valve control.

Condition for Clearing the MIL / DTC

• The ECM turns OFF the MIL when the key is

cycled after a current DTC clears.

• A current DTC clears when the diagnostic runs and

does not fail.

• A history DTC clears after 20 consecutive driving

cycles without a fault. Or clear with the Tech 2 or
accelerator pedal operation.

Diagnostic Aid

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

DTC P0486 (Flash Code 44)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

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 the Tech 2.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Observe the EGR Position Sensor parameter
with the Tech 2.

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

4.9 volts

Go to Step 3

Go to Diagnostic 

Aids

3

1.

Start the engine.

2.

Monitor the Diagnostic Trouble Code (DTC)
Information with the Tech 2.

Is DTC P1635 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.

4.

Observe the EGR Position Sensor parameter
with the Tech 2.

Is the DMM voltage less than the specified value?

0.1 volts

Go to DTC P1635

Go to Step 7

 Engine Control System (4HK1)    6E-181

5

1.

Turn OFF the ignition.

2.

Disconnect the EGR valve harness connector.

3.

Turn ON the ignition, with the engine OFF.

4.

Observe the EGR Position Sensor parameter
with the Tech 2.

Is the DMM voltage less than the specified value?

0.1 volts

Go to Step 6

Go to Step 7

6

1.

Turn OFF the ignition.

2.

Connect a test lamp between the low
reference circuit of the EGR position sensor
harness (pin 2 of E-94 connector) and battery
voltage.

3.

Turn ON the ignition, with the engine OFF.

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 engine
control module (ECM) (pin 86 of E-111
connector) and the EGR position sensor (pin 3
of E-94 connector) 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 101 of E-111 connector) and the
EGR position sensor (pin 2 of E-94 connector)
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

9

1.

Turn OFF the ignition.

2.

Disconnect the EGR position sensor
connector.

3.

Inspect for an intermittent and for a poor
connection at the harness connector of the
EGR position sensor (pin 2 of E-94
connector).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 11

10

1.

Turn OFF the ignition.

2.

Disconnect the ECM harness connector.

3.

Inspect for an intermittent and for a poor
connection on the EGR position sensor circuit
at the harness connector of the ECM (pin 101
of E-111 connector).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 12

11

Replace the EGR valve. Refer to EGR Valve
Replacement in this section. (EGR valve position
sensor is internal to EGR valve)

Did you complete the replacement?

—

Go to Step 13

—

Step

Action

Value(s)

Yes

No