Hi guys,

I wanted to change the fuel filter on my 2008 5.4l F250, and I thought it was a great idea to remove the "fuel pump diode" while the truck was running to drain the fuel pressure where the filter is located. "fuel pump diode" was according to my manual at location 62 in the engine compartment fuse box

The engine stopped directly when I pulled the diode (not after a few seconds as I expected), so I tried to start it with the diode not present, the enginge cranked but did not start.
I then inserted the diode again, and after that the engine does not even crank , instead the Securilock indicator keeps blinking (as far as I know the Truck is not even equipped with Securilock)...

Have tried to remove the battery, charge the battery, pull out fuses at random to see if they are burnt.... Running out of ideas, anyone got a good idea for me to try?

 

If I may suggest, post this on flatratetech.com...there are a lot of MSE's on their who really know their stuff and help the "blind".

 

The ODB2 scanners will not connect to the car anymore either

 

I would check all fuses...& relays (fuses should be in 2 locations maybe 3?.) it maybe that when you pulled the one It set off overloaded another fuse...or during the time you disconnected the battery and reattached it??

presume you mean fuse for Diode ....and code reader will plug in properly just won't read anything

 

if it is for sure a "diode" you pulled out and reinstalled. take it out and flip it around. Diodes only let voltage flow in one direction, they are one way valves for electricity. let me know if that helps !

 

Not Sure if this helps or not but in my e-350 5.4 I have an ecu diode but not fuel pump. The diode is to prevent backflow frequencies from the cop's to the ECU\PCM. Not sure if it tripped something failsafe or possibly damaged the PCM. The diode will go in one way if it is similar to mine.