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I have a 2012 F250 SD with fuses that have no power going to them when you turn the key on. They are accessories fuse to the starter, blower motor, and key components to run the truck. On the engine fuse panel the fuse numbers are 49- 56 That grid should light up when you turn the key on. I'm thinking a relay must operate that grid. If I put a 12V jumper wire to that grid everything works fine. As soon as I pull the jumper truck will shut off. If that grid does not have power the starter will not work. Any ideas where I can start looking?
Last edited by Pauly17; Sep 1, 2021 at 04:22 AM.
Reason: add file
You're on the right track. Fuses F49, F50, F52, F53, F54, F55, & F56 are all fed by the RUN/START Relay which is in the underhood fusebox.
That relay's high side of the coil is fed by fuse F45. The coil is energized by a signal from the BCM. There's a whole lot of stuff that goes on in the background for the BCM to send that signal.
Check fuse F45, swap out the relay with another like relay that isn't critical for operation (mark them first!!) and see if either is the issue. After that, it gets a lot harder....
Also, if you need further assistance, specify which engine and transmission is installed, there are some differences.
YOU ARE THE MAN!!!! It was the 10 amp fuse! Ford guy wanted to replace the main wire Harness.. Giving him a break it was 1:30 at night, and he didn't trouble shoot it to far. Thanks again my friend, you made someone's entire month!
