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Ask Chris (aka- Moose) Your Own Question
Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Ford
Satisfied Customers: 44463
Experience:  16 years experience
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Pcm doesn't seem to recognize the fuel pump control module.

Customer Question

Pcm doesn't seem to recognize the fuel pump control module.
JA: Have you ever replaced the fuel pump, or is this the original?
Customer: Have replaced fuel pump. Truck runs when bypassing fuel pump control module
JA: What is the make/model/year of your car?
Customer: 2005 Ford f250
JA: Are you fixing your F250 yourself? What have you tried so far?
Customer: Have code scanner, and says module failed. However have replaced fuel rail pressure sensor, fuel pump, and fuel pressure control module. Have power to control module.
JA: Anything else you want the mechanic to know before I connect you?
Customer: None that I'm aware. Looking to find if broken wire between pcm and fuel pressure control module is root cause.
Submitted: 1 month ago.
Category: Ford
Expert:  Chris (aka- Moose) replied 1 month ago.

Welcome, I'm Chris (aka Moose), my normal schedule online is around lunch and after dinner past midnight.

Do you need a wire diagram to test the wiring to and form the FPCM?

Is there a good ground to the FPCM?

Do you have a scope to see if there is a signal to the FPCM from the PCM?

Customer: replied 1 month ago.
Would like to know where to check continuity from pcm to fpcm
Ground is good when jumper wire across and running fuel pump on full pressure.
Also, do not have a scope to test signal.
Expert:  Chris (aka- Moose) replied 1 month ago.

Do you have a 5.4 or 6.8?

Customer: replied 1 month ago.
5.4
Customer: replied 1 month ago.
I get a p1235 code.
Expert:  Chris (aka- Moose) replied 1 month ago.

Here is the wire diagram. https://dl.dropboxusercontent.com/u/90220402/FPCM.pdf

Here is the PCM connector view. https://dl.dropboxusercontent.com/u/90220402/175B.png

The 2 wires to the PCM should not have continuity to each other nor to power or ground.

Here are the diag steps for the code you have. https://dl.dropboxusercontent.com/u/90220402/KB.pdf

.

Prior to completing the mandatory rating at the top of your screen. Let me know if I have not yet provided you with ~5 STAR EXCELLENT~service. Reply and let me know in more detail what you need to be pleased with my help. Rating is the only way I am paid from the deposit you made.

Thanks Chris

Customer: replied 1 month ago.
Getting to the continuity and voltage checks in the am. The pcm connection shown is the center one of the three?
So by the motor running it dissolves the issue of the pcm being a failure?
Expert:  Chris (aka- Moose) replied 1 month ago.

I can only tell which PCM connector it is by comparing the wire colors and pins. I highlighted the 2 pins in the diagram and the wire colors are in the first diagram. The fact it runs with the FPDM bypassed does not rule out this portion or function of the PCM to blame.

Customer: replied 1 month ago.
What issues would arise from fuel pump on full voltage?
Expert:  Chris (aka- Moose) replied 1 month ago.

Full voltage results in high fuel pressure. Which makes the engine run rich. Eventual catalytic converter failure. Faster spark plug failure. Lower MPG.

Expert:  Chris (aka- Moose) replied 26 days ago.

Hello again Chris here,

  • Sorry you were not pleased with my help.
  • What would you like to do regarding your question now.
  • This post is coming up on the 7 day mark where it times out. When a post times out, that means it's no longer on my active list (you reply and I may never know it.)

Thanks Chris

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