Which fuse controls the diagnostic port on a 2003 ford e350?

There isn't a single fuse specifically for the diagnostic port (OBD-II) on a 2003 Ford E350. The power to the diagnostic port is usually supplied through a larger circuit, often related to the power distribution box or the general power supply for the vehicle's computer system.

To find the likely culprit, you'll need to consult your owner's manual. Look for the fuse box diagrams. The fuse that might be relevant could be labeled something like:

* Powertrain Control Module (PCM): This is the most likely candidate.

* Data Link Connector (DLC): Less common, but possible.

* Body Control Module (BCM): Less likely, but a possibility if the diagnostic port is tied into a body control function.

If you don't have the owner's manual, you can find a downloadable version online by searching for "2003 Ford E350 owner's manual PDF." The diagrams in the manual will show the fuse box layout and descriptions of what each fuse controls. If you can't find it after checking the likely candidates, it's best to consult a mechanic or automotive electrician.