To find it, you'll likely need to:
* Consult a repair manual specific to your year and model Econoline 150. This is the most reliable method. The manual will show a diagram and often pinpoint the PCM's location.
* Look near the firewall. It's often mounted on or near the firewall, sometimes tucked away.
* Check along the sides of the engine. It could be attached to the engine block or a nearby component.
Without knowing the exact year and engine, providing a precise location is impossible. The PCM is usually a fairly sizable black box with numerous connectors.