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James, Ford Technician
Category: Ford
Satisfied Customers: 3628
Experience:  Ford Senior Master Tech, Ford gas and diesel expert, ASE Certified
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Ford F450 Super Duty XL: 07 f450 6.0 powerstroke has #22 fuse

Customer Question

07 f450 6.0 powerstroke has #22 fuse blowing in dash block. I have isolated to front plug on pcm closest to headlight which according to my all data diagram feeds transmission sensors. If you unplug the front plug then you can turn key to on position without blowing fuse. Truck has a utility body on it and had some lights wired in so I am wondering if my diagram is correct and if the so could some wires spliced into the brake lights or pulled of transmission 12v signal be causing fuse to blow from a short. It is a 20 amp fuse. I assume that all data wiring diagram is correct but figured should make sure before spent hours underneath truck guessing
Submitted: 2 years ago.
Category: Ford
Expert:  Tim Mohr replied 2 years ago.
Hi, my nqme is Tim, it is a very common problem for the electric fan clutch to short internally and cause this, have you tried unplugging the fan clutch and se if it bows the fuse?
Customer: replied 2 years ago.
Fan is unplugged as are every other engine sensor and glow plug module. The two wiring plugs of the three are still plugged in to pcm. It is isolated to the front pcm plug
Expert:  Tim Mohr replied 2 years ago.
then it can only be an internal short to ground inside the PCM, as these are the only powered by the 22 fuse, it wont be anything in the transmission or the brake switch, the PCM is shorted out, Tim
Customer: replied 2 years ago.
Can I swap a different 6.0 pcm from 03 f350 with 6.0 to test ?
Expert:  Tim Mohr replied 2 years ago.
No, the computers are different, and also the computer will also need to be reflashed to your vin number and the key will also need to be reprogrammed into the new computer, unfortunately,Tim
Customer: replied 2 years ago.
Will the on still show signals from sensors even though it is bad. I can monitor the gauges if wire ecm fuse with copper wire and remove fuse it still won't crank but I have bypassed starter and it spins fine
Expert:  Tim Mohr replied 2 years ago.
Yes, it can, but none the less, its a bad compuer, no other sensor will cause this fuse to blow, it can only be in the computer, the fan clutch, the egr module, the glow plug module, mass air flow sensor, if all these are plugged in, but the pcm is disconnect, and it does not blow, then it can only be an internal short inside the PCM,Tim
Expert:  James replied 2 years ago.
I'm sorry I don't want to interupt. The mass air flow wires rub against the shock tower and run through the 12v wire blowing the fuse. If the wiring is followed down you will see a small knick in the wire harness.

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