My truck is switching to 4th gear manual on
its own what causes that and the engine
light came on it does it after it hits like 50
miles per hour
Sounds like the overdrive band or torque convertor is the issue, they get worn and burnt over time. Is the fluid brown and not red? Since the engine light is on, you can scan the car for the codes, my guess is you will get some transmission codes to help you determine the next course of action. Your local auto parts store will scan the truck for free. Post the 4 digit codes back here.
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