I purchased a refurbished Logitech Harmony 670 a few months back, and tried to set it up. I had serious issues getting it to work properly when switching inputs on my Vizio SV470XVT1A LCD TV. It would often land on the wrong input. The way the Vizio handles input switching is rather annoying in that it doesn't have a discrete button for each input. It has a button for each input type, and cycles through them. Alternatively, it has an input button that cycles through all inputs. I did a lot of Googling, without luck. I eventually gave up on it.

I recently started messing with it again. I did even more Googling, and found a few tricks. I tried them all without luck. I did stumble across a really helpful forum entry that got me on the right track. Specifically, item 26b.

While testing individual commands, as per item 26b, I discovered that the TV responds to commands like 'InputHdmi3' to get to a discrete inputs, without cycling. I also discovered that the TV config from Logitech uses 'SetHMIInput HTMI 3', which appears to cycle. Thus the effect I saw of not landing on the right input.

1. Go to the Devices tab in the programming software, and choose 'Settings' for your Vizio TV.
2. Choose 'Adjust Inputs' and click 'Next'.
3. Make sure 'Method 2' is selected and click 'Next'.
4. Adjust the inputs and ordering to match your TV, then click 'Next'.
5. Map all of the inputs to the matching 'InputHdmi3' type values.

Blog:

http://techsanctuary.com/vizio-switching-issues-lo...