Eztrucker78

Here's my question my o/d light flashes and I lose lockup. But it only happens after driving for a half hour or more. I have checked the codes it 452 so I replaced the sensor but it still happens. My question is could it be my alternator causing this when the truck is cold the gauge is above half but after awhile of driving its at half or lower. So I'm wondering if it's dropping voltage and causing me to get the code?