Answer
Sep 26, 2025 - 03:02 PM
On a ’99 F-350 Super Duty with the 5.4L, the PCM (engine computer) is mounted in the passenger side of the engine bay, right up against the firewall. You’ll see a big multi-pin harness plug going through the firewall into the cab — that’s the PCM connector.
To get at it, you usually pull back the plastic splash shield/kick panel inside the passenger footwell. The module itself is partly inside the cab, partly sticking through the firewall, with the connector accessible from the engine bay.
This manual shows the exact location with a diagram, plus the removal/installation procedure if you need to swap it. Totally worth getting so you don't have to guess where it is ✌🏻
