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Shawn
Shawn, Auto Service Technician
Category: Ford
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Experience:  16 years experience Ford,Nissan and Honda dealership in all areas
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2004 ford f150 5.4L p0190 problem code fuel rail pressure

Resolved Question:

2004 ford f150 5.4L p0190 problem code fuel rail pressure sensor circut malfunction__
Submitted: 3 years ago.
Category: Ford
Expert:  Shawn replied 3 years ago.
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Shawn :

Hi, Thank you for asking your question on JustAnswer, my name is XXXXX XXXXX I will be assisting you today with your question.

Shawn :

Does the vehicle run?

Customer:

yes

Customer:

the truck runs perfectly

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Shawn :








P0190 - Fuel Rail Pressure (FRP) Sensor Circuit Malfunction
The comprehensive component monitor (CCM) monitors the FRP sensor to the PCM for VREF voltage. The test fails when the VREF voltage from the PCM drops to a voltage less than a minimum calibrated value.

  • VREF open in harness.

  • VREF open in sensor.

  • VREF open in PCM.


Verify a VREF voltage between 4 and 6 volts.
Customer:

how do i check the VREF voltage?

Customer:

if the voltage is out of our range what is the solution?

Shawn :

Most likely cause is the fuel pump driver module. Check the circuits of the Fuel Pump Driver Module (FPDM) to verify the cause of the problem.
The White (W) wire at FPDM pin 5 should show battery voltage, whenever the ignition key is on, from the fuel pump relay and inertia switch.
The Black/Yellow (BK/Y) wire at FPDM pin 3 is a dedicated ground for the FPDM.
The Pink/Black (PK/BK) wire at FPDM pin 4 is power out of the FPDM feeding the fuel pump. This circuit should show battery voltage whenever the key is in the run position.
The Brown/White (BR/WH) wire at FPDM pin 2 is the fuel pump ground circuit. This circuit is duty cycled with a ground signal from the FPDM based on the command from the Powertrain Control Module (PCM). Back probing this circuit with a jumper wire and grounding it should result in 70+ PSI of fuel pressure if there is power to the fuel pump and the pump is good.
The White /Yellow (W/Y) wire at FPDM pin 6 is the command signal sent from the PCM to the FPDM. The voltage on this circuit is generally a 1-5 volt reading, the higher the voltage reading, the higher pressure is being commanded.
The Light Blue/Orange (LB/O) wire at FPDM pin 1 is a feedback signal sent from the FPDM back to the PCM

Shawn :

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Shawn, Auto Service Technician
Category: Ford
Satisfied Customers: 3756
Experience: 16 years experience Ford,Nissan and Honda dealership in all areas
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