Isuzu KB P190. Manual - part 484

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-319

Remove the Meter (10A) fuse that supplies
voltage to the IP cluster.

Turn ON the ignition, with the engine OFF.

Measure the voltage from the cruise set lamp
control circuit in the ECM harness connector
(pin 49 of C-58) to a good ground.

Is the voltage less than the specified value?

1 volt

Go to Step 8

Go to Step 10

Turn OFF the ignition.

Reinstall the Meter (10A) fuse.

Turn ON the ignition, with the engine OFF.

Connect a 3-amp fused jumper wire between
the cruise set lamp control circuit of the ECM
harness connector (pin 49 of C-58) and a
known good ground.

Is the cruise main lamp illuminated?

—

Go to Step 12

Go to Step 9

Test the control circuit between the ECM (pin
49 of C-58) and the IP cluster (pin 23 of B-23)
for an open circuit or high resistance.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 11

Repair the short to battery or ignition voltage on the
control circuit between the ECM (pin 49 of C-58)
and the IP cluster (pin 23 of B-23).

Did you complete the action?

—

Go to Step 15

—

Inspect for an intermittent and for a poor
connection at the harness connector of the IP
cluster (pins 23 of B-23).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 13

Turn OFF the ignition.

Disconnect the ECM harness connector.

Inspect for an intermittent and for poor
connections on the cruise main or set lamp
control circuit at the harness connector of the
ECM (pin 49 or 50 of C-58).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 14

Repair or replace the IP cluster.

Did you complete the repair or replacement?

—

Go to Step 15

—

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

Did you complete the replacement?

—

Go to Step 15

—

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

Is the action complete?

—

Go to 1 of 2 Step 2

—

Step

Action

Value(s)

Yes

6E-320 ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Turbocharger Control System Check

Description

The position of the turbocharger nozzle is controlled by
the ECM. The ECM utilizes a turbocharger nozzle
control solenoid valve and a boost pressure sensor to
control the turbocharger nozzles. When the engine is
not under load, the turbocharger nozzles are in an open
position, or no boost condition. When the engine is
under load, the ECM commands the control solenoid
valve to close the turbocharger nozzles, thus
increasing the boost. The ECM will vary the boost
dependant upon the load requirements of the engine.
The ECM uses a pulse width modulation (PWM) on the
control circuit to open and control the solenoid valve.

Notice:

• This Circuit/ System Testing is only applicable to

high output engine.

Schematic Reference: Engine Controls Schematics

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

Circuit/ System Testing Turbocharger Control System Check

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check -
Engine Controls?

—

Go to Step 2

Go to Diagnostic

System Check -
Engine Controls

Install a scan tool.

Turn OFF the ignition for 30 seconds.

Turn ON the ignition, with the engine OFF.

Monitor the DTC Information with a scan tool.

Is DTC P0045, P0107, P0108, P0112, P0113,
P0116, P0117, P0118, P0234, P0299, P0638,
P0698, P0699, P1196, P1197, P1198, P2227,
P2228 or P2229 also set?

—

Go to Applicable

DTC

Go to Step 3

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-321

Inspect the following conditions:

• Air leakage around the boost pressure

sensor objects that block the sensor hole.

• Air leaking around any of the air induction

tubing between the turbocharger and
intake manifold. Check for damaged
components and for loose clamps.

• Misrouted, disconnected or kinked

turbocharger nozzle control actuator
vacuum hoses. Refer to Vacuum Hose
Routing Diagram in this section for
correct routing.

• Turbine shaft binding causing lower

turbocharger spinning speeds. Refer to
the Turbocharger in engine mechanical
section for diagnosis.

• Turbocharger nozzle control actuator for

a stuck condition or slow movement.
Refer to Turbocharger in engine
mechanical section for testing.

• Intake throttle valve sticking. Perform the

Intake Throttle Solenoid Control with a
scan tool.

• Restricted air cleaner element, restricted

or collapsed air tubing between the air
cleaner and the boost pressure sensor.

• Oil in the air induction tubing causing an

incorrect boost pressure sensor signal.
When there is adhesion of oil inside of
tubing, intercooler or turbocharger it
needs to be wiped off.

Repair the condition as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 4

Place the transmission in Neutral and set the
parking brake.

Accelerate the engine between idle and
W.O.T. (accelerator pedal full travel) many
times while observing the Desired Boost
Pressure and Boost Pressure parameter with
a scan tool.

Drive the vehicle that the engine speed is
more than 2000 RPM and the Calculated
Engine Load parameter reaches at least 50%
for longer than 10 seconds (such as
acceleration on ramp) while comparing the
Boost Pressure to the Desired Boost
Pressure.

Does the Boost Pressure parameter follow within
the specified value?

±20 kPa (±3

psi)

System OK

Go to Step 5

Step

Action

Value(s)

Yes

6E-322 ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Turn OFF the ignition.

Disconnect the vacuum hose from the
turbocharger nozzle control actuator
diaphragm.

Connect a hand-held vacuum pump (5-8840-
0279-0/ J-23738-A) to the disconnected
vacuum hose.

Start the engine and let idle.

Perform the Turbocharger Solenoid Control
with a scan tool.

Command the solenoid valve Increase and
Decrease while observing the vacuum pump.

Does the hand-held vacuum pump reading more
than 50 cmHg (20 inHg) when commanded
maximum Increase and ZERO range when
commanded minimum Decrease?

—

Go to Step 8

Go to Step 6

Inspect the following conditions:

• Misrouted, disconnected, kinked or

plugged turbocharger nozzle actuator
control vacuum hose.

• Misrouted, disconnected, kinked or

plugged solenoid valve ventilation hose.

• Misrouted, disconnected, kinked or

plugged vacuum source hose or pipe.

Repair or replace as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 7

Replace the turbocharger nozzle control solenoid
valve.

Did you complete the replacement?

—

Go to Step 8

—

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

Clear the DTCs with a scan tool if set.

Turn OFF the ignition for 30 seconds.

Did you complete the action?

—

Go to Step 2

—

Step

Action

Value(s)

Yes

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