No check engine light but transmission won't upshift

Hi, my name is Devin. I am an auto repair expert with the Car Genius team here at RepairPal. I'm sorry to hear you're having trouble with your Ram 1500. If your transmission isn't upshifting but there's no check engine light, it could be an issue with the transmission's internal components, such as a worn-out solenoid, a faulty governor pressure sensor, or low transmission fluid. Sometimes, the transmission fluid can get low or dirty, which can cause shifting problems even if there's no light. Since you can shift manually, this points to a potential issue with the automatic shifting mechanism rather than a problem with the engine. I recommend checking the fluid levels and condition first and then inspecting the transmission system to rule out any mechanical or electrical issues. If you need more advice, have any other questions about your vehicle, or would like to get connected to a RepairPal Certified shop near you, we have you covered. Give us a call at 877-913-1554, and we will happily help you out!