Will a 03 expedition transmission work in my f150 if i rewire the harness?

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! Swapping in that 2003 Expedition transmission might seem like a close match, but transmissions can be finicky when it comes to wiring and sensors. The mismatch in sensors and zip-tied connections could definitely cause shifting issues and confuse the speedometer. Rewiring or adapting sensors without fully matching the transmission control module (TCM) can throw the system off, making it act like you’re doing 100 mph when you’re not. You might be missing a pin or proper signal for the speed sensor. Double-check wiring and fluid levels first, but you might need a more specific solution like a custom tune. If you need any further advice or want help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554.