At least half a year ago the wrench icon started showing up on the dash once in awhile. It would be on for a few days, then it would be off for a few days. Over the course of a couple months it showed up more and more frequently, until now it has been on all the time for a few months. Also in the last few months, I have had some idling issues right after starting, when the engine is cold. I live in central Canada and we've had some very cold temperatures this winter, and the truck will start with a bit of a hiccup, and then idle high (1200) for a few minutes before the idle drops down to 800. If I touch the gas pedal, or shift into gear before the idle drops, then the truck will stall. If I wait until it warms up a bit, and the idle has dropped, then it seems to respond normally.
I finally bought a Bluetooth OBD2 reader and I get the code U0109: lost communication with the fuel pump control module.
Online research told me where it was, and I had a look at it... Looks OK with no obvious wire breaks:


I called three parts stores in my city and none of them were familiar with this part, and one even told me that they had never ever sold one... Now I'm second-guessing if this is a part that I should replace.
Any suggestions?

 

Depending on your engine (5.0 in my case), fuse 27 and TSB 15-0137 may apply. The Motorcraft fuse relocation kit is cheap, labor about $100 at independent mechanic if you can't do it yourself. Fairly easy fix.

 

Thanks, I've got a 5.4 and I looked at fuse 27... actually I unplugged it while the truck was running and it instantly died. Looked it over and the fuse is good 😁
I think I'll have to look somewhere else.

 

I would pull the connector and clean it out,and put some dielectric grease to seal out the moisture, also that one wire that's out of the wire loom in your pic, has nick in the insulation..

 

Fuse 27 issue does not break the fuse, it melts the fusebox. So, make sure you are looking for the right damage. Probably worth relocating, anyway, people with every engine have reported issues with this fuse.

The fuel pump module is a fairly common replacement, regardless of what your local stores said. It's back there in the spray and cold, and older ones tended to rust until they made them more plastic. But, clean up the wires first, as jeremyha said.

 

Just want to subscribe here as my 2010 5.4 has the wrench light on and the same code for months, haven't figured out what's wrong yet, truck runs fine tho.

 

 

Stay tuned. Hopefully this weekend I can make room in the garage and get in out of the cold to take a closer look at that module, clean up the wires, and check the contacts.