Isuzu KB P190. Manual - part 435

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-123

12

Replace the FT sensor. Refer to FT Sensor
Replacement.

Did you complete the replacement?

—

Go to Step 14

—

13

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

Did you complete the replacement?

—

Go to Step 14

—

14

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 15

15

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-124   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

DTC P0192 or P0193 (Flash Code 245)

Circuit Description

The fuel rail pressure (FRP) sensor is installed to the
fuel rail and it detects the fuel pressure in the fuel rail,
converts the pressure into a voltage signal, and sends
the signal to the ECM. The sensor has the following
circuits.

• 5 volts reference circuit

• Low reference circuit

• FRP sensor signal circuit

The ECM monitors the FRP sensor signal voltage.
Higher fuel rail pressure provides higher signal voltage
while lower pressure provides lower signal voltage. The
ECM calculates actual fuel rail pressure (fuel pressure)
from the voltage signal and uses the result in fuel
injection control and other control tasks. If the ECM
detects an excessively low or high signal voltage, DTC
P0192 or P0193 will set.

Condition for Running the DTC

• DTCs P0652 and P0653 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 FRP sensor signal

voltage is less than 0.4 volts. (DTC P0192)

• The ECM detects that the FRP sensor signal

voltage is more than 4.75 volts. (DTC P0193)

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 FRP substitution of default value.

• The ECM limits fuel injection quantity.

• The ECM inhibits pilot injection.

• 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.

• Electromagnetic interference may affect

intermittent condition.

Schematic Reference: Engine Controls Schematics

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

Circuit/ System Testing DTC P0192

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 P0652 also set?

—

Go to DTC P0652

Go to Step 3

3

Observe the Fuel Rail Pressure (FRP) Sensor
parameter with a scan tool.

Is the FRP Sensor parameter less than the
specified value?

0.4 volts

Go to Step 4

Go to Diagnostic 

Aids

4

1.

Turn OFF the ignition.

2.

Disconnect the FRP sensor harness
connector.

3.

Turn ON the ignition, with the engine OFF.

Is the FRP Sensor parameter more than the
specified value?

4.7 volts

Go to Step 5

Go to Step 6

5

Connect a DMM between the 5 volts reference
circuit (pin 3 of E-48) and a known good ground.

Is the DMM voltage more than the specified value?

4.7 volts

Go to Step 8

Go to Step 7

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-125

6

1.

Test the signal circuits between the ECM (pins
48 and 68 of E-90) and the FRP sensor (pin 2
of E-48) for the following conditions:

• A short to ground

• A short to the low reference circuit

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 11

7

1.

Test the 5 volts reference circuit between the
ECM (pin 47 of E-90) and the FRP sensor (pin
3 of E-48) 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

8

1.

Inspect for an intermittent and for a poor
connection at the harness connector of the
FRP sensor (pin 3 of E-48).

2.

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 a poor
connection at the harness connector of the
ECM (pin 47 of E-90).

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 FRP sensor. Refer to FRP Sensor
Replacement.

Did you complete the replacement?

—

Go to Step 12

—

11

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

Did you complete the replacement?

—

Go to Step 12

—

12

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 3

Go to Step 13

13

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-126   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Circuit/ System Testing DTC P0193

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 P0653 also set?

—

Go to DTC P0653

Go to Step 3

3

Observe the Fuel Rail Pressure (FRP) Sensor
parameter with a scan tool.

Is the FRP Sensor parameter more than the
specified value?

4.7 volts

Go to Step 4

Go to Diagnostic 

Aids

4

1.

Turn OFF the ignition.

2.

Disconnect the FRP sensor harness
connector.

3.

Connect a DMM between the signal circuit
(pin 2 of E-48) and a known good ground.

4.

Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified value?

5.3 volts

Go to Step 10

Go to Step 5

5

1.

Connect a test lamp between the signal circuit
(pin 2 of E-48) and a known good ground.

2.

Connect a DMM between the probe of the test
lamp and a known good ground.

Is the DMM voltage more than the specified value?

4.7 volts

Go to Step 9

Go to Step 6

6

Connect a 3-amp fused jumper wire between the
signal circuit and the low reference circuit (pins 1
and 2 of E-48).

Is the FRP Sensor parameter less than the
specified value?

0.1 volts

Go to Step 11

Go to Step 7

7

1.

Test the low reference circuit between the
ECM (pin 69 of E-90) and the FRP sensor (pin
1 of E-48) for an open circuit or high
resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 8

8

1.

Test the signal circuit between the ECM (pins
48 and 68 of E-90) and the FRP sensor (pin 2
of E-48) for an open circuit or high resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 12

9

1.

Test the signal circuits between the ECM (pins
48 and 68 of E-90) and the FRP sensor (pin 2
of E-48) for a short to any 5 volts reference
circuit.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 14