2000 Ford Expedition P0781 P1744 Code: Transmission Shift Issues and Slipping After Warm-Up
Hello everyone, My 2000 Ford Expedition (5.4L V8, 4X4, 100-series transmission, 163,000 miles) recently developed a check engine light followed by a flashing O/D indicator. Prior to this, the transmission operated normally. After the warning lights activated, the vehicle began shifting more abruptly and now exhibits noticeable slipping in both forward and reverse gears—especially after warming up. A local auto parts store scanned the system and retrieved two diagnostic codes: - P0781: 1st to 2nd Gear Shift Error - P174-than System Malfunction (TCC) Based on these codes, is the issue likely related to transmission solenoids or fluid levels? Or could it point to a more expensive repair such as internal transmission failure? Any insights or experiences with this specific combination of codes in a 2000 Ford Expedition would be greatly appreciated.
I replaced the transmission fluid and filter as a first step since it's the most affordable and straightforward fix. After refilling, I took it for a test drive—everything seemed fine for about five minutes. However, at the first stop, the engine unexpectedly shut down. It restarted easily, but after that, the transmission began slipping significantly during operation. The vehicle also started exhibiting rough idling and intermittent feedback that made it feel like the system was attempting to shut down or stall. Since then, the check engine light and O/D warning have not reappeared even after limping home. The engine ran smoothly before this issue occurred. I'm now wondering if the fluid change actually worsened the problem—could there be a deeper mechanical fault behind these symptoms? Any thoughts on whether solenoid failure or internal transmission wear might be at play?