Isuzu KB P190. Manual - part 424

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-79

DTC P0088 (Flash Code 118)

Description

The common rail fuel system is comprised of two fuel
pressure sections: a suction side between the fuel tank
and the fuel supply pump and a high-pressure side
between the fuel supply pump and the fuel injectors.
Fuel is drawn from the fuel tank via a feed pump and
then pumped into the fuel rail by two plungers, all of
which are internal to the fuel supply pump. This high
pressure is regulated by the ECM using the fuel rail
pressure (FRP) regulator dependant upon values from
the FRP sensor attached to the fuel rail.
If the ECM detects that the fuel pressure went
excessively high for a certain length of time, this DTC
will set (First Stage). If the ECM detects that during the
same ignition cycle the fuel pressure rose even higher
than the amount to set DTC P0088 for a certain length
of time, the engine is stopped (Second Stage). If the
engine is stopped, the fuel pressure was too high and
the pressure limiter valve did not active or did not active
quick enough.

Condition for Running the DTC

• DTCs P0192 and P0193 are not set.

• The battery voltage is more than 9 volts.

• The ignition switch is ON.

• The engine is running.

Condition for Setting the DTC

First Stage

• The ECM detects that the fuel rail pressure is more

than 197 MPa (28,600 psi) for longer than 5
seconds.

Second Stage

• The ECM detects that the fuel rail pressure is more

than 200 MPa (29,000 psi) for longer than 5
seconds.

Action Taken When the DTC Sets

First Stage

• 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 limits fuel injection quantity.

• The ECM inhibits pilot injection.

• The ECM inhibits cruise control.

Second Stage

• The ECM illuminates the SVS lamp when the

diagnostic runs and fails. Refer to DTC Type
Definitions for Action Taken When the DTC Sets -
Type C. (Euro 4 Specification)

• 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.
(Except Euro 4 Specification)

• The ECM limits fuel injection quantity.

• The ECM inhibits pilot injection.

• The ECM inhibits cruise control.

• The ECM stops engine running when the vehicle

speed is lower than 5 km/h (3 MPH) for 5 seconds.
The engine will run after the key is cycled when the
ignition has been tuned OFF for longer than 10
seconds.

Condition for Clearing the DTC

First Stage

• Refer to DTC Type Definitions for Condition for

Clearing the MIL/ DTC - Type A.

Second Stage

• Refer to DTC Type Definitions for Condition for

Clearing the SVS Lamp/ DTC - Type C. (Euro 4
Specification)

• Refer to DTC Type Definitions for Condition for

Clearing the MIL/ DTC - Type A. (Except Euro 4
Specification)

Diagnostic Aids

• An intermittently sticking Fuel Rail Pressure

regulator may have allowed the fuel pressure to
become high enough to set this DTC.

• Normal Fuel Rail Pressure readings on the scan

tool with the engine running in neutral at idle is
around 27 to 33 MPa (3,900 to 48,00 psi) after
warm up.

• A skewed FRP sensor value can set this DTC. The

FRP Sensor on the scan tool should read 0.9 to
1.0 volt with the key ON and engine OFF after the
engine has stopped running for a minimum of 1
minute.

Schematic Reference: Fuel System Routing Diagram
and Engine Controls Schematics

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

Circuit/ System Testing DTC P0088

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

6E-80 ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Install a scan tool.

Turn OFF the ignition for 30 seconds.

Start the engine.

Monitor the DTC Information with a scan tool.

Is DTC P0089, P0091, P0092, P0192, P0193,
P0201 - P0204, P0219, P1064, P1065, P124B or
P2146 - P2151 set?

—

Go to Applicable

DTC

Go to Step 3

Turn OFF the ignition.

Place the transmission in Neutral and set the
parking brake.

Start the engine.

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

Does the Fuel Rail Pressure parameter ever
exceed the specified value?

190 MPa

(27,600 psi)

Go to Step 4

Go to Step 11

Turn OFF the ignition.

Wait 1 minute for the fuel pressure to bleed
down from the fuel rail.

Turn ON the ignition, with the engine OFF. DO
NOT start the engine.

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

Does the scan tool indicate within the specified
value?

0.9 to 1.0 volt

Go to Step 5

Go to Step 10

Start the engine.

Perform the Cylinder Balance Test with a scan
tool.

Command each injector OFF and verify an
engine speed change for each injector.

Is there an injector that does not change engine
speed when commanded OFF?

—

Go to Step 13

Go to Step 6

Check the fuel system line connections
between the fuel tank and the fuel supply
pump for tightness and all fuel hoses for cuts,
cracks and for the use of proper clamps.

Notice: Air in the fuel system will cause fuel rail
pressure fluctuations especially at high engine
speed and load, which may set this DTC.

Start the engine and check for high side fuel
system leaks at the fuel supply pump and fuel
rail.

Notice: Fuel may leak under the cylinder head
cover from the inlet high pressure line. In such
case, the engine oil level will rise. Inspect for fuel
leakage into the engine oil.

Repair any fuel system leaks as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 7

Step

Action

Value(s)

Yes

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-81

Notice: Make sure the in-tank fuel pump operation
before performing the following procedures. Refer
to In-tank Fuel Pump System Check in this section.

Turn OFF the ignition.

Disconnect the fuel hose from the fuel supply
pump suction side. In order to measure the
discharged fuel amount, put the hose into a
bottle or a container with a scale. (The inlet of
a bottle or a container must be larger than the
diameter of hose.)

Turn ON the ignition for 20 seconds, with the
engine OFF.

Turn OFF the ignition for 10 seconds.

Perform 3 and 4 three times. The accumulated
fuel of three ignition cycles must be more than
300 cc. (Normal amount is more than 100 cc
per one ignition cycle.)

Notice: If there is a leak or a restriction on the
suction side, the fuel from the hose will not flow out
sufficiently that is most likely caused by fuel
leakage, clogged fuel filter, kinked or crushed fuel
hose or pipe. Also inside the fuel tank for any
foreign materials may be getting drawn into the fuel
line pickup.

Repair fuel system leaking or restrictions as
necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 8

Remove the fuel hose that connects to the fuel
supply pump suction side and substitute a
clear hose.

Notice: The hose must be cleaned before
connecting to the fuel line. Otherwise, foreign
material internal to the hose may damage the fuel
supply pump.

Bleed the fuel system. Repeat as necessary
until the engine starts.

Let the engine run at idle for at least 1 minute.

Observe the clear hose while holding the
engine speed higher than 3000 RPM for a
minimum of 1 minute.

Notice: If many air bubbles appear in the fuel,
check the fuel line connections between the fuel
supply pump and the fuel tank for tightness and all
fuel hoses for cuts, cranks and for the uses of
proper clamps.

Repair or replace as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 9

Step

Action

Value(s)

Yes

6E-82 ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Turn OFF the ignition.

Disconnect the FRP regulator harness
connector.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the FRP regulator (pins 1 and 2
of E-50).

Disconnect the ECM harness connector.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the ECM (pins 34, 50, 54 and 70
of E-90).

Test for high resistance on each circuit.

Repair the connection(s) or circuit(s) as
necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 14

Turn OFF the ignition.

Disconnect the FRP sensor harness
connector.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the FRP sensor (pins 1, 2 and 3
of E-48).

Disconnect the ECM harness connector.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the ECM (pins 47, 48, 68 and 69
of E-90).

Test for high resistance on each circuit.

Repair the connection(s) or circuit(s) as
necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 12

Notice: An intermittent problem by foreign material
in the fuel is suspected.
Replace the fuel filter cartridge. Refer to Fuel Filter
Cartridge Replacement.

Did you complete the replacement?

—

Go to Step 15

—

Replace the FRP sensor. Refer to FRP sensor
Replacement.

Did you complete the replacement?

—

Go to Step 15

—

Important: Replacement fuel injector must be
programmed.
Replace the appropriate fuel injector that does not
change engine speed when commanded OFF.
Refer to Fuel Injector Replacement/ Fuel Injector
ID Code Data Programming.

Did you complete the replacement?

—

Go to Step 15

—

Step

Action

Value(s)

Yes

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