Isuzu N-Series. Manual - part 717

6E-290    Engine Control System (4HK1) 

22

1.

Test for an open or high resistance in the CAN
Low or High circuit (which ever voltage
reading did not read between 1.3 – 3.7 volts in
Step 16) between the DRM and joint
connection.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 28

23

1.

Test for an open or high resistance in the CAN
Low or High circuit (which ever voltage
reading did not read between 1.3 – 3.7 volts in
Step 15) between the TCM and joint
connection.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 29

24

1.

Test for an open or high resistance in the CAN
Low or High circuit (which ever voltage
reading did not read between 1.3 – 3.7 volts in
Step 17) between the ECM and joint
connection.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 31

25

Repair the short circuit each other across the CAN
Low and High circuits among the resistor 1, TCM
and EHCU.

Did you complete the repair?

—

Go to Step 38

—

26

Repair the short circuit each other across the CAN
Low and High circuits among the resistor 2, ECM,
DRM and EHCU.

Did you complete the repair?

—

Go to Step 38

—

27

1.

Test the CAN Low and High circuits between
the resistor 1 (pins 1 and 2 of B-387
connector) and the EHCU (pins 14 and 15 of
J-177 connector) for an open circuit or high
resistance.

2.

Test the CAN Low and High circuits between
the resistor 2 (pins 1 and 2 of B-431
connector) and the EHCU (pins 26 and 27 of
J-177 connector) for an open circuit or high
resistance.

3.

Inspect for an intermittent, for poor
connections and corrosion on the CAN Low
and High circuits at the harness connector of
the each resistor.

4.

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

Did you find and correct the condition?

—

Go to Step 38

Go to Step 30

28

1.

Inspect for an intermittent, for poor
connections and corrosion on the CAN Low
and High circuits at the harness connector of
the DRM (pins 2 and 8 of B-429 connector).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 34

Step

Action

Value(s)

Yes

No

 Engine Control System (4HK1)    6E-291

29

1.

Inspect for an intermittent, for poor
connections and corrosion on the CAN Low
and High circuits at the harness connector of
the TCM (pins 2 and 3 of B-427 connector).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 35

30

1.

Inspect for an intermittent, for poor
connections and corrosion on the CAN Low
and High circuits at the harness connector of
the EHCU (pins 14, 15, 26 and 27 of J-177
connector).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 36

31

1.

Inspect for an intermittent, for poor
connections and corrosion on the CAN Low
and High circuits at the harness connector of
the ECM (pins 18 and 37 of J-191 connector).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 37

32

Replace the resistor 1.

Did you complete the replacement?

—

Go to Step 38

—

33

Replace the resistor 2.

Did you complete the replacement?

—

Go to Step 38

—

34

Replace the DRM. Refer to Data Recording Module
(DRM) Replacement.

Did you complete the replacement?

—

Go to Step 38

—

35

Replace the TCM. Refer to Transmission Control
Module (TCM) Replacement in the transmission
section.

Did you complete the replacement?

—

Go to Step 38

—

36

Replace the EHCU. Refer to Electric Hydraulic
Control Unit (EHCU Replacement in the Anti-lock
Brake section).

Did you complete the replacement?

—

Go to Step 38

—

37

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 38

—

38

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.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 39

39

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-292    Engine Control System (4HK1) 

EGR Control System Check

Description
The engine control module (ECM) controls the EGR
valve opening based on the barometric pressure,
engine speed, engine coolant temperature and fuel
injection quantity. The ECM controls the EGR valve by
controlling the EGR motor. The EGR valve position is
detected by the EGR valve position sensor, and
relayed to ECM.

Condition for Running the EGR Control

• The engine coolant temperature is between 65

°C

(149

°F) and 95°C (198°F).

• The barometric pressure (BARO) is more than 90

kPa (13 psi).

EGR Control System Check
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.

Turn ON the ignition, with the engine OFF.

4.

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

Are any DTCs set in which the “Action Taken When
the DTC Sets” under that particular code states,
“The ECM inhibits EGR valve control”?

—

Refer to Applicable 

DTC

Go to Step 3

3

1.

Turn OFF the ignition.

2.

Inspect for the following conditions:

• An EGR valve gasket that is missing or

damaged.

• EGR gas leakage any of the EGR

passages between the exhaust manifold
and intake manifold.

• Restricted or collapsed EGR passage

between the exhaust manifold and the
EGR valve.

• Any type of restriction in the exhaust

system.

• Restrict air cleaner element, restrict or

collapsed air tubing between the air
cleaner and the intake manifold.

• Skewed engine coolant temperature

(ECT) sensor. Refer to Temperature vs
Resistance table to test the ECT sensor
at various temperature levels to evaluate
the possibility of a skewed sensor.

• Skewed barometric pressure (BARO)

sensor. Determine the outside barometric
pressure from your location specified in
the altitude vs barometric pressure table.
Refer to Altitude vs Barometric Pressure.

• Any water intrusion in the induction

system.

• Air leaking around any of the air induction

tubing between the air cleaner and the
intake manifold.

3.

Repair the condition as necessary.

Did you find and correct the condition?

—

Go to Step 10

Go to Step 4

 Engine Control System (4HK1)    6E-293

4

1.

Turn OFF the ignition for 30 seconds.

2.

Start the engine and warm up (allow engine
coolant temperature to reach at least 70

°C

[158

°F]).

3.

Observe the EGR Position Variance
parameter with the Tech 2.

Does the EGR Position Variance parameter within
the specified value?

± 5%

Go to Step 5

Go to Step 6

5

1.

Perform the EGR Control test with the Tech 2
several times.

2.

Command the Desired EGR Position
“Increase” and “Decrease” with the Tech 2
while observing the EGR Position Variance.

Does the EGR Position Variance parameter follow
within the specified value?

± 5%

System OK

Go to Step 6

6

1.

Turn OFF the ignition.

2.

Remove the EGR valve assembly from the
engine. Refer to EGR Valve Replacement in
this section.

3.

Inspect the following for possible causes of
EGR valve sticking.

• Restricted EGR valve by foreign

materials

• Excessive deposits at valve

Did you find and correct the condition?

—

Go to Step 10

Go to Step 7

7

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-94 connector).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 10

Go to Step 8

8

1.

Turn OFF the ignition.

2.

Disconnect the engine control module (ECM)
harness connector.

3.

Inspect for an intermittent, for poor
connections and corrosion on the EGR valve
circuits at the harness connector of the ECM
(pins 86, 87, 101, 103 and 111 of E-111
connector).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 10

Go to Step 9

9

Replace the EGR valve. Refer to EGR Valve
Replacement in this section.

Did you complete the replacement?

—

Go to Step 10

—

10

Reconnect all previously disconnected components
or harness connector(s).

Is the action complete?

—

Go to Step 2

—

Step

Action

Value(s)

Yes

No