Desperately need electrical experts for my 2006 GT

Here’s the story…I did a wire tuck a couple of years ago, everything has been working great, until now. I’ve been experiencing a fuel pressure issue. I thought at first it was the pump, so I switched it out, still nothing. Went on to the FPDM, switched that out, nothing. I then moved on to the BEC that is now located in my glove box —pictures below— to check if any wires were loose or damaged. I unclipped the two plastic fasteners from the BEC housing, inspected the wires, everything looked fine. Put the BEC back in the plastic housing, boom, fuel pressure. Maybe a wire was too snug? Everything worked great again for a couple weeks, then it happened again.

Basically, it’s to the point of when I unfasten the BEC from the housing and let it hang down by the wires, I get fuel pressure. When I put it back in the housing, fuel pressure goes away. However, if I start the car with the BEC hanging down and let the car run while mounting the BEC back in the housing, car still runs. The minute I turn the car off and back on with the BEC back in place, car immediately dies because it lost fuel pressure again.

I’m getting power to the white power wire to the FPDM. I have a limited knowledge on the relationship between the FPDM and how it works with the other sensors/ components but I thought maybe its not getting pressure because it’s not getting the correct signal from the PCM. However, I get a little over 8v from the FPDM fuel pump control wire and a little over 10v from its monitor wire.

I checked the PCM power wires of pins 35, 36, and 45, and I’m getting a 12v reading.

I just need some guidance in pin pointing which circuit is giving me the problem and I can take it from there. I doubt it’s the actual BEC that needs replacing but perhaps? I soldered all my splices and put heat shrink around them—pictures below of my solders—. I was very meticulous in this project so this is very frustrating as you can imagine.








^^No fuel pressure when in this position





^^This position I get pressure

I would check the pins in the fuse block...unbolt the block from the fuse box and reinstall it and makes sure its pushed in good and while its apart wiggle the wires and make sure the pins aren't sliding too far back.

I'll try to give you a hand with this mess. First off it sounds like you have developed an intermittent open wire in your relocation process. So we are going to trouble shoot using a style called divide and conquer.

I want you to go to the car and mount the BEC like it should be. Then I want you to verify that the problem is there simply by turning the key and listening and observing for no fuel pump activity or pressure. Assuming the problem is there do the following:

Pull the drivers side kick panel and locate your intertia fuel shut off switch. Pull connector C282 and locate pin 2 on the wiring harness. It will be a Dark green with Yellow stripe wire. Set up your voltmeter to read DC and place the black lead to ground and the red lead on pin 2. Turn the key on. Do you get 12-13 vdc? You may have to cycle the car on and off several times to confirm. If you get no voltage then we will begin trouble shooting from there back to the BEC unit next.

IF NO and I suspect the result will be NO, next go to the BEC and check for voltage at the C1035A pin C12 which as you guess will be Dark Green with Yellow stripe in color. Do you get 12-13vdc there? YES? Fix the bad wire or connection at C1035A-C12. NO? READ ON.

Next pull the FUEL PUMP RELAY. Inspect the socket it mounts in for damage. With your meter check to see if you have 12-13vdc at the relay connector in the FPR socket marked 87. You should. If not you may have a damaged BEC unit. If you do have 12-13vdc move on.

Switch the meter to measure continuity. With the black lead still attached to ground, place the red lead on the relay connector in the socket marked 86. You should read less than 2 ohms. If it read extremely high resistance or infinity fix the open wire between this connector and ground. It routes out Connector C1035-F5 and is black. If it checks good move on.

Set the meter back to DC and place the red lead on the connector in the relay socket marked 85. Turn the key on and see if you observe 12-13vdc. NO? Next check for voltage at Connector C1035-F4 (violet wire) for 12-13 vdc. YES? The BEC is again suspect. NO? You have bad wiring between the BEC and the SJB between Connector C1035-F4 on the BED and C2280-12 on the SJB. This is the violet wire. You will also see that at the BEC there are two wires on this connector pin. The other violet wire feed the on signal to the PCM.

Hope this helps. Don't forget to reconnect things as you go. And do not disturb the BEC any more than possible while troubleshooting because doing so can give erroneous results while troubleshooting a pesky intermittent open like this. I am goingto go spend some time with my pissed off wife now. LOL! Make use of the effort I have put in to this. Thanks.

Sorry for the late reply, I am also getting help from Lito and wanted to give him some feedback. After I posted this, the next day I went to confirm the problem still existed...it's working just fine now, even when I move the fuse box around. Go figure. I turned the car on and off plus just put the key on to hear the pump cycle, everything still works for the last few days. Love the intermittent problems.

wildbillcody- one of the first things I did was depin and repin all the wires to make sure everything was seated in the connectors.


redfirepearlgt- Before I posted this I basically did everything you suggested, so I'm glad we are on the same page. I just didn't want to post EVERYTHING I have done so far. (Again, before I wrote this and before it started working again) I was getting 12v to the fuel inertia switch. Thats also why I was getting 12v to the FPDM white wire. I also checked for voltage and continuity for the fuel pump relay. Everything checked out. However, one discrepancy has occurred between what you are saying and my wiring diagram. The diagram that is free online shows the F4 violet wire having 2 wires, one to the SJB and the other to the PCM. My vehicle did not have the wire going to the PCM. I looked up the wiring diagram for my VIN # on fords site, turns out I dont have a wire going to the PCM from that location on my model. I checked for voltage from that location to the SJB and was getting the 12v. So that checked out. This is how I came to the conclusion that it must be a wire going to the PCM.

I was hoping to get some insight on what I should trouble shoot for next if the problem comes back?

Chasing an intermittent problem is like trying to hit a moving target. I deal with this every day on the old worn out CNC machining centers and CNC vertical lathes at work that have been neglected and cobbled back together for years before I ever arrived at my current job. I feel your pain. I once spent two days watching a CNC laser drop out laser cutting power about once every 45-90 minutes of cutting time before I finally isolated the problem and resolved it when I was in field service work. So it's never easy believe me to hunt them down.

Ford must have eliminated that wire from the PCM to the BEC. Doesn't make sense to me why it would be there if the PCM relay is to provide the voltage to the pcm to begin with, but then again engineers can sometimes do things for reasons unknown in the name of redundancy that is later found to not be needed. I guess if it comes back start again ate intertia switch and don't wiggle anything while following the signal path back we have discussed.

Nice looking car btw. What wheels are on it? I'm already beginning to miss the chrome lips on my car. Just wasn't able to find a staggered setup like that with some nice lip in the front without paying the devils price for them.

Haha I paid the devils price for them. They're HRE

Good freaking grief. No doubt at those prices you have few running around with wheels that match yours. DAG! Four rims is a Hellion Turbo kit.

Yea :/....I've had this car since 2006 though. Only owner, so it's been a decade long excursion.