Component Location
General Description

Fuel pressure regulator valve is integrated with high pressure pump and controls common rail pressure as regulating the quantity of fuel which is delivered to common rail. In order to control rail pressure to be optimum to current driving condition, ECM controls fuel pressure regulator operating current(with the method of duty-control) using Rail pressure regulator valve signal, RPM and APS signal.

The lower Fuel pressure regulator valve current is, the more fuel is supplied to common rail. Thus it leads rail pressure to be high. On the contrary, the higher Fuel pressure regulator valve current is, the less fuel is supplied to common rail. Thus it leads rail pressure to be low. Therefore, when Fuel pressure regulator valve current becomes "0", as if there is open spot in Fuel pressure regulator valve circuit or connector is disconnected, maximum fuel quantity is supplied to common rail, so the pressure of common rail rise to maximum value.

DTC Description

P0254 is set when excessive current in power circuit of Fuel pressure regulator valve(integrated with high pressure pump) is detected for more than 0.22 sec.. This code is due to short to battery in power circuit or Fuel pressure regulator valve internal short.

DTC Detecting Condition

Item

Detecting Condition

Possible Cause

DTC Strategy

●

Voltage monitoring

●

Fuel pressure regulator valve circuit

●

Fuel pressure regulator valve component

Enable Conditions

●

IG KEY "ON"

Threshold Value

●

Short to battery (power circuit in Fuel pressure regulator valve)

Diagnostic Time

●

220ms

Fail Safe

Fuel cut

NO

EGR Off

NO

Fuel Limit

YES

Check Lamp

YES

Specification

Fuel pressure regulator valve resistance

Operating frequancy

2.9 ~ 3.15Ω (20℃)

185 Hz

Diagnostic Circuit Diagram
Signal Waveform

Fig.1) Waveform of Fuel pressure regulator valve at idle.

Monitor GDS Data
1.

Connect GDS to Data Link Connector (DLC).

2.

Warm engine up to normal operating temperature.

3.

Turn "OFF" electrical devices and A/C.

4.

Monitor "FUEL PRESSURE MEASURED", "RAIL PRESS. REGULATOR1", "INJ. PUMP REGULATOR" parameter on the GDS.

Specification :

Idle(without load)

Accelerating(stall test)

Diagnosis

INJ. PUMP REGULATOR

38 ± 5%

32 ± 5%

duty decreases

FUEL PRESSURE

MEASURED

28.5 ± 5 Mpa

145 ± 10 Mpa

press. increases

RAIL PRESS.

REGULATOR1

19 ± 5%

48 ± 5%

duty increases

Fig 1) Service data of Fuel pressure regulator valve at idle.

note

The waveform of rail pressure regulator valve installed at common rail shows 19% duty at idle,

duty rises to approx. 48% at acceleration to raise rail pressure. Duty rise means the increase of current.

→ If current rises, the returning quantity of fuel deliverd to common rail decreases and common rail pressure rises.

Terminal and Connector Inspection
1.

Electrical systems consist of a lot of harness and connectors, poor connection of terminals can cause various problems and damge of component.

2.

Perform checking procedure as follows.

(1)

Check damage of harness and terminals : Check terminals for contact resistance, corrosion and deformation.

(2)

Check connecting condition of ECM and component connector : Check terminal seperation, damage of locking device and connecting condition between terminal and wiring.

note

Disconnect the pin which requires checking at male connector and insert it to the terminal at female connector for checking connecting condition. ( after checking, reconnect the pin at correct position. )

3.

Is the problem found?

▶ Repair the trouble causing part and go to "Verification of Vehicle Repair".

▶ Go to "Power Circuit Inspection".

Power Circuit Inspection
1.

Check power circuit voltage

(1)

IG KEY "OFF", ENGINE "OFF".

(2)

Disconnect Fuel pressure regulator valve connector.

(3)

IG KEY "ON".

(4)

Measure the voltage between power terminal of FPRV harness connector and chassis ground.

Specification : 11.5V~13.0V

(5)

Is the measured voltage within the specification?

▶ Go to "Control Circuit Inspection".

▶ Repair open between power terminal of FPRV harness connector and ECM harness connector and go to "Verification of Vehicle Repair".

Control Circuit Inspection
1.

Check monitoring voltage in control circuit

(1)

IG KEY "OFF", ENGINE "OFF".

(2)

Disconnect Fuel pressure regulator valve connector.

(3)

IG KEY "ON".

(4)

Measure the voltage between power terminal of FPRV harness connector and chassis ground.

Specification : 3.2V~3.7V

(5)

Is the measured voltage within the specification?

▶ Go to "Component Inspection"

▶ When voltage is not detected : Go to "2. Check open in control circuit" as follows.

▶ When high voltage is detected : Repair short to battery and go to "Verification of Vehicle Repair".

2.

Check open in control circuit

(1)

IG KEY "OFF", ENGINE "OFF".

(2)

Disconnect Fuel pressure regulator valve and ECM connector.

(3)

Check continuity between control terminal of FPRV harness connector and ECM harness connector.

Specification : Continuity ( below 1.0Ω )

(4)

Is the measured resistance within the specification?

▶ Repair short to ground in Fuel pressure regulator valve control circuit and go to "Verification of Vehicle Repair".

▶ Repair open in Fuel pressure regulator valve control circuit and go to "Verification of Vehicle Repair".

Component Inspection
1.

Check Fuel pressure regulator valve component resistance

(1)

IG KEY "OFF", ENGINE "OFF".

(2)

Disconnect rail pressure control valve connector.

(3)

Measure the resistance between signal terminal and power terminal of FPRV connector.(component side).

Specification : 2.9 ~ 3.15Ω (20°C)

(4)

Is Fuel pressure regulator valve component resistance within the specification?

▶ Go to "Verification of Vehicle Repair".

▶ Replace High pressure pump ass’y and go to "Verification of Vehicle Repair".

Verification of Vehicle Repair

After a repair, it is essential to verify that the fault is corrected.

1.

After connecting GDS select "DIAGNOSTIC TROUBLE CODES(DTCs)" mode.

2.

Clear recorded DTC using GDS.

3.

Drive the vehicle within DTC "Enable conditions" in "General information".

4.

After selecting "DIAGNOSTIC TROUBLE CODES(DTCs)" mode and check if DTC is recorded again.

5.

Are any DTCs recorded ?

▶ Go to the DTC guide of recorded NO. in GDS.

▶ System operates within specification.

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