2003 Ford Expedition, No Run, No Fuel Pump Operation, Code P0231

This 2003 Ford Expedition came in with a no run condition. A quick check found no fuel pressure and a code P0231 (low voltage on fuel pump monitor circuit). I decided to go to the interior fuse box, where my wiring diagrams, stated the fuel pump relay and fuse are located. There are a couple of covers that have to be removed.

Pull the edge loose at the firewall end and pivot the cover back.

There is a black plastic cover that has to be pulled off of the actual fuse box.


Since my wiring diagrams stated the relay was located in the fuse box, but did not give a specific position, I looked in the owners manual for more info. No luck there. I did some reading and found that there are five internal, non serviceable relays inside the fuse block. My next test would involve locating the output circuit  from the relay.  The wiring diagrams stated that the fuel pump relay output wire was dark green/yellow and it was located in cavity 3 of connector C270K. I placed a jumper wire into the cavity to backprobe the circuit, no volts. Since my backprobe wire is part of a fused jumper wire, I connected battery voltage to the circuit and started the vehicle. This told me that the fuel pump, inertia switch and related wiring were all okay.

I checked fuse #34 with the key on and it had power and was good so that eliminated a faulty pcm relay and related wiring. The next step was to locate the light blue/orange wire in cavity #12 of the C270B connector. It is in the lower right hand corner of the twelve cavity connector just below the connector that I am backprobing in the picture above. When the ignition is turned on the reading was near zero volts and after a few seconds it went to battery voltage. This told me that the pcm was using a ground to energize the fuel pump relay coil. With all of this testing I knew without a doubt that the fuel pump relay that is part of the interior fuse box was faulty.

Disconnect the battery first before removing the fuse block. There is a battery feed cable that also has to be disconnected on the rear edge of the fuse box. It is located under a cover. I have pictures of that at the end of this post. There is only one bolt that holds this fuse block in place.

I unplugged all of the wiring. There are connectors on the top where testing was done and on the edge. Above and below the mounting bolt.

In the rear.

This connector has a slide mechanism. I have my finger in the pull handle for it.

The fuse block removed from the vehicle. You can see the battery terminal post on the lower left edge.

I carefully removed all fuses and relays from the fuse block and laid them out in the order removed.

I took the back cover off of the fuse block and started disassembling it.

Once I had it opened it was easy to see the damage. Slightly right of center.

The damage was even easier to see from the relay side of the board. I feel fairly confident that if this problem would have been caught soon enough, the solder joint could have been repaired or a new relay installed (if one could have been located).

The old fuse block on the left and the new one on the right.

I plugged everything back in and bolted the fuse block in place.

This is the end of the battery cable that I referred to earlier.

The cover for the battery stud on the fuse block.

I put all of the covers back on, cleared the codes and test drove the vehicle. This one is done.

This repair will generally apply to Ford and Lincoln full sized trucks and suv’s in the same years//body style. Check diagrams and component locators before jumping any circuits, as I did.

111 discussions on “2003 Ford Expedition, No Run, No Fuel Pump Operation, Code P0231”

  1. Hi sparky this is saul i checked it with a testlite and ignition on . Im just starting to wonder if is my fuse panel i cant find anything wrong .and even the fuse panel looks ok i took it apart already and it dont look burned or nothing .im tired of messin with this piece of junk..

  2. I just wanted to say thank you for this post. I had same no start situation and problem with my 2003 Expedition. Purchased a used panel on Ebay for $65 with free shipping. I had to tweak the panel since it was for an ’04 vs ’03. Similar to your photo, they are different a little. The truck fired right up. There are many posts with similar issues on the ’03’s.
    Thanks again, Garry

  3. Hi sparky im having trouble with my 2003 navigator it was runing fine until it just died on the street and then started back up and madeit home killed it wanted to startit back up an nothing just turns over and no start and it looks like i have no fire to any of the crank n cam sensors or fuel pump relays i checked just about every where on this thing n cant find nothing can you help me please my name is saul by the way.

  4. Thank you!!!
    I had just filled up tank and ran it through the car wash. Came directly home, parked, came out an hour later and crank/no start. Wouldn’t even try to catch. Spent an hour on phone talking to dealership, garages, and mechanic friends. All said it had to be my fuel pump. I really didn’t think it could be because absolutely no previous warning signs of pump going out. Jumped on internet and found this blog. Did the testing like you advised and started right up. Pulled fuse panel and disassembled just to make sure. Buried relay looked exactly like picture. Just ordered new panel since mine beyond repair. Thank you for saving my wallet and my sanity.

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