1. press TV 2. press and hold SETUP for two blinks 3. enter 9-9-4 4. tap SETUP for one blink
5. enter 0-0-1-7-4
6. Push the Input button in the lower left corner of your Comcast Remote.
Now when you are in TV mode that button may work.
What that is called is an EFC Code (Extended Function Code). You have to find one that works with your TV. You can also try LG codes on Vizio TV's. Some are known to work really well on certain models.