Isuzu N-Series. Manual - part 676

6E-126 Engine Control System (4HK1)

P0192 (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 engine control module (ECM). The
FRP sensor has the following circuits.

• 5 volts reference circuit.
• Low reference circuit.
• FRP sensor signal circuit.

The ECM supplies 5 volts to the FRP sensor on the 5
volts reference circuit. The ECM also provides a ground
on the low reference circuit. Higher fuel rail pressure
provides higher FRP sensor voltage while lower
pressure provides lower FRP sensor 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. The ECM monitors the
FRP sensor signal for voltage outside the normal
range. If the ECM detects an excessively low FRP
sensor signal voltage, this DTC will set.

Condition for Running the DTC

• DTCs P1630 and P1635 are not set.
• The ignition switch is ON.
• The ignition voltage is more than 18 volts.

Condition for Setting the DTC

• The ECM detects that the FRP sensor signal

voltage is less than 0.7 volts.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM limits accelerator control range.
• The ECM inhibits pilot injection.
• The ECM inhibits EGR valve control.

Condition for Clearing the MIL / DTC

• The ECM turns OFF the MIL when the key is

cycled after a current DTC clears.

• A current DTC clears when the diagnostic runs and

does not fail.

• A history DTC clears after 20 consecutive driving

cycles without a fault. Or clear with the Tech 2 or
accelerator pedal operation.

Diagnostic Aid

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Notice:

• Electrical or magnetic interference may affect

intermittent condition.

• The Differential Fuel Rail Pressure parameter on

the Tech 2 will be fixed at 0 MPa (0 psi) when this
DTC is set.

DTC P0192 (Flash Code 245)
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

Did you perform the Diagnostic System Check –
Engine Controls?

—

Go to Step 2

Go to Diagnostic

System Check –

Engine Controls

Install the Tech 2.

Turn OFF the ignition for 30 seconds.

Start the engine.

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

Is DTC P1635 also set?

—

Go to DTC P1635

Go to Step 3

Start the engine.

Observe the Fuel Rail Pressure (FRP) Sensor
parameter with the Tech 2.

Is the FRP Sensor parameter less than the
specified value?

0.7 volts

Go to Step 4

Go to Diagnostic

Aids

Engine Control System (4HK1) 6E-127

Turn OFF the ignition.

Disconnect the FRP sensor harness
connector.

Turn ON the ignition, with the engine OFF.

Observe the Fuel Rail Pressure (FRP) Sensor
parameter with the Tech 2.

Is the FRP Sensor parameter more than the
specified value?

4.5 volts

Go to Step 5

Go to Step 6

Turn OFF the ignition.

Connect a DMM between the 5 volts reference
circuit of the FRP sensor harness (pin 3 of E-
113 connector) and a known good ground.

Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified value?

4.5 volts

Go to Step 8

Go to Step 7

Test the signal circuits between the engine
control module (ECM) (pins 82 and 90 of E-
111 connector) and the FRP sensor (pin 2 of
E-113 connector) for the following conditions:

• A short to ground
• A short to the low reference circuit

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 11

Test the 5 volts reference circuit between the
ECM (pin 87 of E-111 connector) and the FRP
sensor (pin 3 of E-113 connector) for an open
circuit or high resistance.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 9

Turn OFF the ignition.

Inspect for an intermittent and for a poor
connection at the harness connector of the
FRP sensor (pin 3 of E-113 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 10

Turn OFF the ignition.

Disconnect the ECM harness connector.

Inspect for an intermittent and for a poor
connection on the FRP sensor circuit at the
harness connector of the ECM (pin 87 of E-
111 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 11

Replace the FRP sensor. Refer to Fuel Rail
Pressure (FRP) Sensor Replacement in this
section.

Did you complete the replacement?

—

Go to Step 12

—

Step

Action

Value(s)

Yes

6E-128 Engine Control System (4HK1)

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 12

—

Reconnect all previously disconnected
harness connector(s).

Clear the DTCs with the Tech 2.

Turn OFF the ignition for 30 seconds.

Start the engine.

Operate the vehicle within the Conditions for
Running the DTC.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 13

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

Engine Control System (4HK1) 6E-129

P0193 (Flash Code 245)

• 5 volts reference circuit.
• Low reference circuit.
• FRP sensor signal circuit.

Condition for Running the DTC

• DTCs P1630 and P1635 are not set.
• The ignition switch is ON.
• The ignition voltage is more than 18 volts.

Condition for Setting the DTC

• The ECM detects that the FRP sensor signal

voltage is more than 4.5 volts.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM limits accelerator control range.
• The ECM inhibits pilot injection.
• The ECM inhibits EGR valve control.

Condition for Clearing the MIL / DTC

• The ECM turns OFF the MIL when the key is

cycled after a current DTC clears.

• A current DTC clears when the diagnostic runs and

does not fail.

• A history DTC clears after 20 consecutive driving

cycles without a fault. Or clear with the Tech 2 or
accelerator pedal operation.

Diagnostic Aid

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Notice:

• Electrical or magnetic interference may affect

intermittent condition.

• The Differential Fuel Rail Pressure parameter on

the Tech 2 will be fixed at 0 MPa (0 psi) when this
DTC is set.

DTC P0193 (Flash Code 245)
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

Did you perform the Diagnostic System Check-
Engine Controls?

—

Go to Step 2

Go to Diagnostic

System Check –

Engine Controls

Install the Tech 2.

Turn OFF the ignition for 30 seconds.

Start the engine.

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

Is DTC P1635 also set?

—

Go to DTC P1635

Go to Step 3

Start the engine.

Observe the Fuel Rail Pressure (FRP) Sensor
parameter with the Tech 2.

Is the FRP Sensor parameter more than the
specified value?

4.5 volts

Go to Step 4

Go to Diagnostic

Aids

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