Isuzu KB P190. Manual - part 429

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-99

3

1.

Turn OFF the ignition.

2.

Disconnect the MAF sensor harness
connector.

3.

Connect a test lamp between the ignition
voltage feed circuit (pin 1 of E-47) and a
known good ground.

4.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

—

Go to Step 4

Go to Step 5

4

1.

Turn OFF the ignition for 30 seconds.

2.

Connect a 3-amp fused jumper wire between
the ignition voltage feed circuit and the signal
circuit (pins 1 and 3 of E-47).

3.

Turn ON the ignition, with the engine OFF.

Is the MAF Sensor parameter more than the
specified value?

4.9 volts

Go to Step 7

Go to Step 6

5

Repair the open circuit or high resistance between
the ECM Main Relay (pin 1 of X-12) and the MAF
sensor (pin 1 of E-47) for and open circuit or high
resistance. Check the Engine (10A) fuse first.

Did you complete the repair?

—

Go to Step 11

—

6

1.

Test the signal circuit between the ECM (pin
40 of E-90) and the MAF sensor (pin 3 of E-
47) 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 11

Go to Step 8

7

1.

Inspect for an intermittent and for poor
connections at the harness connector of the
MAF sensor (pins 1 and 3 of E-47).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 11

Go to Step 9

8

1.

Turn OFF the ignition.

2.

Disconnect the ECM harness connector.

3.

Inspect for an intermittent and for a poor
connection at the harness connector of the
ECM (pin 40 of E-90).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 11

Go to Step 10

9

Replace the MAF sensor. Refer to MAF Sensor
Replacement.

Did you complete the replacement?

—

Go to Step 11

—

10

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

Did you complete the replacement?

—

Go to Step 11

—

Step

Action

Value(s)

Yes

No

6E-100   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Circuit/ System Testing DTC P0103

11

1.

Reconnect all previously disconnected fuse,
relay or 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 12

12

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 Mass Air Flow (MAF) Sensor
parameter with a scan tool.

Is the MAF Sensor parameter more than the
specified value?

4.9 volts

Go to Step 3

Go to Diagnostic 

Aids

3

1.

Turn OFF the ignition for 30 seconds.

2.

Disconnect the MAF sensor harness
connector.

3.

Turn ON the ignition, with the engine OFF.

Is the MAF Sensor parameter less than the
specified value?

0.1 volts

Go to Step 4

Go to Step 5

4

Connect a test lamp between the low reference
circuit (pin 2 of E-47) and battery voltage.

Does the test lamp illuminate?

—

Go to Step 7

Go to Step 6

5

1.

Test the signal circuit between the ECM (pin
40 of E-90) and the MAF sensor (pin 3 of E-
47) 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 11

Go to Step 10

6

1.

Test the low reference circuit between the
ECM (pin 43 of E-90) and the MAF sensor (pin
2 of E-47) for an open circuit or high
resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 11

Go to Step 8

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-101

7

1.

Inspect for an intermittent and for a poor
connection at the harness connector of the
MAF sensor (pin 2 of E-47).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 11

Go to Step 9

8

1.

Turn OFF the ignition.

2.

Disconnect the ECM harness connector.

3.

Inspect for an intermittent and for a poor
connection at the harness connector of the
ECM (pin 43 of E-90).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 11

Go to Step 10

9

Replace the MAF sensor. Refer to MAF Sensor
Replacement.

Did you complete the replacement?

—

Go to Step 11

—

10

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

Did you complete the replacement?

—

Go to Step 11

—

11

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 12

12

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-102   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

DTC P0107 or P0108 (Flash Code 32)

Circuit Description

The boost pressure sensor is located in the air
induction tubing. The boost pressure sensor is a
transducer that varies voltage according to changes in
the air pressure inside the air tubing. The sensor has
the following circuits.

• 5 volts reference circuit

• Low reference circuit

• Boost pressure sensor signal circuit

The boost pressure sensor provides a signal to the
ECM on the signal circuit, which is relative to the
pressure changes in the air tubing. The ECM should
detect a low signal voltage at a low boost pressure,
such as low engine load. The ECM should detect high
signal voltage at a high boost pressure, such as high
engine load. If the ECM detects an excessively low or
high signal voltage, DTC P0107 or P0108 will set.

Condition for Running the DTC

• DTCs P0698 and P0699 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 boost pressure sensor

signal voltage is less than 0.1 volts. (DTC P0107)

• The ECM detects that the boost pressure sensor

signal voltage is more than 4.75 volts. (DTC
P0108)

Action Taken When the DTC Sets

• 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.

• The ECM uses a boost pressure substitution of

default value.

• The ECM limits fuel injection quantity.

• 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 A.

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 P0107

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 P0698 also set?

—

Go to DTC P0698

Go to Step 3

3

Observe the Boost Pressure Sensor parameter
with a scan tool.

Is the Boost Pressure Sensor parameter less than
the specified value?

0.1 volts

Go to Step 4

Go to Diagnostic 

Aids

4

1.

Turn OFF the ignition.

2.

Disconnect the boost pressure sensor
harness connector.

3.

Connect a DMM between the 5 volts reference
circuit (pin 3 of E-107) 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