Isuzu KB P190. Service manual - part 418

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-55

Scan Tool Output Controls 

Scan Tool Output Control

Descriptions

Fuel Supply Pump Learn 

Resetting

The purpose of this test to reset the fuel supply pump adjustment value.

Important: The fuel supply pump relearn procedure must be done when the fuel supply 
pump or engine is replaced, or an ECM from another vehicle is installed. Refer to Fuel 
Supply Pump Replacement.

Fuel Pressure Control

The purpose of this test is for checking whether the fuel rail pressure is changing when 
commanded within 30 to 80MPa (4,350 to 11,600psi) when commanded.  Faulty fuel supply 
pump, fuel rail pressure (FRP) regulator, pressure limiter valve or other fuel lines could be 
considered if the differential fuel rail pressure is large.

Pilot Injection Control

The purpose of this test is for checking whether the pilot fuel injection is operated when it is 
commanded to ON/ OFF. Faulty injector(s) could be considered if engine noise does not 
change when commanded OFF.

Injection Timing Control

The purpose of this test is for checking whether the main injection timing is changing when 
commanded Retard/ Advance within -5 to  5

°CA.

Injector Force Drive

The purpose of this test is for checking whether the fuel injector is correctly operating when 
commanded ON.  Faulty injector(s) could be considered if it does not create a clicking noise 
(solenoid operating noise), contains an interrupted noise or has abnormal noise when 
commanded ON.

Cylinder Balance Test

The purpose of this test is for checking whether the fuel injector is operating when 
commanded ON/ OFF.  Faulty injector(s) could be considered if engine does not change 
speed when commanded OFF.

Intake Throttle Solenoid Control

The purpose of this test is for checking whether the intake throttle valve is correctly moved 
with command.  Restricted valve movement by foreign materials, excessive deposits or a 
faulty valve could be considered if the position difference is large.

EGR Solenoid Control

The purpose of this test is for checking whether the EGR valve is correctly moved with 
command.  Restricted valve movement by foreign materials, excessive deposits or a faulty 
valve could be considered if the position difference is large.

Swirl Control Solenoid Control

The purpose of this test is for checking whether the swirl control solenoid is operating when 
commanded ON.  Faulty circuit(s) or a faulty solenoid could be considered if not energizing 
when commanded ON.

Turbocharger Solenoid Control

The purpose of this test is for checking whether the turbocharger nozzle control actuator is 
correctly moved with command. Restricted actuator movement by foreign materials, 
excessive deposits, misrouted vacuum hoses, a faulty solenoid or a faulty actuator could be 
considered if the actuator is not moved correctly.

Glow Relay Control

The purpose of this test is for checking whether the glow relay is operating when 
commanded ON.  Faulty circuit(s) or a faulty glow relay could be considered if not energizing 
when commanded ON.

Glow Plug Lamp Control

The purpose of this test is for checking whether the glow indicator lamp is operating when 
commanded ON. Faulty circuit(s) or an open circuit could be considered when not operating 
when commanded ON.

Malfunction Indicator Lamp 

(MIL) Control

The purpose of this test is for checking whether the MIL is operating when commanded ON. 
Faulty circuit(s) or an open circuit could be considered when not operating when 
commanded ON.

Service Vehicle Soon (SVS) 

Lamp Control

The purpose of this test is for checking whether the SVS lamp is operating when 
commanded ON. Faulty circuit(s) or an open circuit could be considered when not operating 
when commanded ON.

Cruise Main Lamp Control

The purpose of this test is for checking whether the cruise main lamp is operating when 
commanded ON. Faulty circuit(s) or an open circuit could be considered when not operating 
when commanded ON.

Cruise Set Lamp Control

The purpose of this test is for checking whether the cruise set lamp is operating when 
commanded ON. Faulty circuit(s) or an open circuit could be considered when not operating 
when commanded ON.

6E-56   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Scan Tool Does Not Power Up

Circuit Description

The data link connector (DLC) is a standardized 16-
cavity connector.  Connector design and location is
dictated by an industry wide standard, and is required
to provide the following:

• Scan tool power battery positive voltage at

terminal 16.

• Scan tool power ground at terminal 4.

• Common signal ground at terminal 5.

The scan tool will power up with the ignition OFF.
Some modules however, will not communicate unless
the ignition is ON.

Schematic Reference: Engine Controls Schematics

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

Circuit/ System Testing Scan Tool Does Not Power Up

Step

Action

Value(s)

Yes

No

1

Important: Make sure the scan tool works properly
on another vehicle before using this chart.

1.

Turn OFF the ignition.

2.

Inspect the Meter (+B) (10A) fuse in the cabin
fuse block.

Is the Meter (+B) (10A) fuse open?

—

Go to Step 2

Go to Step 3

2

Replace the Meter (+B) (10A) fuse. If the fuse
continues to open, repair the short to ground on
one of the circuits that is fed by the Meter (+B)
(10A) fuse or replace the shorted attached
component.

Did you complete the repair?

—

Go to Step 7

—

3

1.

Check each circuit at the data link connector
(DLC) (B-58) for a backed out, spread or
missing terminal.

2.

Repair the terminal as necessary.

Did you find and complete the repair?

—

Go to Step 7

Go to Step 4

4

Connect a test lamp between the +B circuit (pin 16
of B-58) at the DLC and a known good ground.

Does the test lamp illuminate?

—

Go to Step 6

Go to Step 5

5

Repair the open in the battery voltage circuit to the
DLC.

Did you complete the repair?

—

Go to Step 7

—

6

1.

Test each ground circuit at the DLC (pins 4
and 5 of B-58) for an open circuit or high
resistance.

2.

Repair the circuit(s), clean or tighten ground
as necessary.

Did you find and correct the condition?

—

Go to Step 7

Go to Intermittent 

Conditions

7

1.

Connect the scan tool to the DLC.

2.

Attempt to turn ON the scan tool.

Does the scan tool ON?

—

System OK

Go to Step 1

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-57

Scan Tool Does Not Communicate with CAN Device

Circuit Description

The ECM, transmission control module (TCM) (AISIN
A/T only) and immobilizer control unit (ICU) all
communicate with the scan tool over the controller area
network (CAN) link. The ECM, TCM, ICU and the data
recording module (DRM) communicate with each other
over the same CAN link. If no immobilizer system is
installed, the instrument panel (IP) cluster has a CAN
terminating resistor instead of the ICU.

Diagnostic Aids

The following conditions will cause a loss of CAN serial
data communication between the TCM and ICU or
between the scan tool and any control module:

• A CAN serial data circuit open

• A CAN serial data circuit shorted to ground

• A CAN serial data circuit shorted to voltage

• An internal condition within a module or connector

on the CAN serial data circuit, that causes a short
to voltage or ground to the CAN serial data circuit

Schematic Reference: Engine Controls Schematics

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

Circuit/ System Testing Scan Tool Does Not Communicate with CAN Device

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

Important: Make sure the CANdi module is not
malfunctioning. When functioning properly, the
CANdi module LED will be flashing. In the event of
a problem, the LED will be continually illuminated
or not illuminated.

1.

Install a scan tool.

2.

Turn ON the ignition, with the engine OFF.

3.

Attempt to establish communication with the
listed control modules.

• ECM

• Immobilizer Control Unit (ICU) (If so

equipped)

• Transmission control module (TCM)

(AISIN A/T only)

Does the scan tool communicate with any of the
listed control modules?

—

Go to Step 3

Go to Step 7

3

Does the scan tool communicate with the ECM?

—

Go to Step 4

Go to Lost 

Communication with 

The Engine Control 

Module (ECM)

4

Notice: If no AISIN automatic transmission is
installed, skip to Step 5.

Does the scan tool communicate with the TCM?

—

Go to Step 5

Go to Diagnostic 

System Check - 

Transmission 

Controls

5

Notice: If no immobilizer system is installed, skip to
Step 6.

Does the scan tool communicate with the ICU?

—

Go to Step 6

Go to Diagnostic 

System Check - 

Immobilizer 

Controls

6

Test the CAN Low and High serial data circuit for an
intermittently short to ground or intermittently short
to voltage.  Then, test the CAN Low and High serial
data circuit for an intermittently open (based on
which control module did not communicate) at the
connection in the circuit.

Did you find and correct the condition?

—

Go to Step 19

System OK

6E-58   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

7

1.

Inspect for an intermittent, for poor
connections and for corrosion at the data link
connector (DLC) (pins 6 and 14 of B-58).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 19

Go to Step 8

8

Notice: If no data recording module (DRM) is
installed, skip to Step 9.

1.

Turn OFF the ignition.

2.

Disconnect the DRM C-139 harness
connector.

3.

Turn ON the ignition, with the engine OFF.

4.

Attempt to communicate with the ECM, TCM
and ICU.

Does the scan tool communicate with the ECM,
TCM and ICU?

—

Go to Step 14

Go to Step 9

9

1.

Turn OFF the ignition.

2.

Reconnect the DRM harness connector if
disconnected.

3.

Disconnect the ECM J1 (E-90) and J2 (C-58)
harness connectors.

4.

Turn ON the ignition, with the engine OFF.

5.

Attempt to communicate with the TCM and
ICU.

Does the scan tool communicate with the TCM and
ICU?

—

Go to Step 15

Go to Step 10

10

Notice:  If no AISIN automatic transmission is
installed, skip to Step 11.

1.

Turn OFF the ignition.

2.

Reconnect the ECM J1 (E-90) and J2 (C-58)
harness connectors.

3.

Disconnect the TCM C-94 and C-95 harness
connectors.

4.

Turn ON the ignition, with the engine OFF.

5.

Attempt to communicate with the ECM and
ICU.

Does the scan tool communicate with the ECM and
ICU?

—

Go to Step 16

Go to Step 11

11

Notice: If no immobilizer system is installed, skip to
Step 12.

1.

Turn OFF the ignition.

2.

Reconnect the ECM J1 (E-90) and J2 (C-58)
harness connectors if disconnected.

3.

Reconnect the TCM C-94 and C-95 harness
connectors if disconnected.

4.

Disconnect the ICU B-68 harness connector.

5.

Turn ON the ignition, with the engine OFF.

6.

Attempt to communicate with the ECM and
TCM.

Does the scan tool communicate with the ECM and
TCM?

—

Go to Step 17

Go to Step 13

Step

Action

Value(s)

Yes

No