Sometimes Failsafes can Bugger up the Radio System. I had a problem like that too.....
Double/Triple check that you did the installation exactly as the instructions said....
Check all the Connectors, you mighrt have one thats not making the best contact that it Can.
BUNDLE all your cables neatly and rout them as far from the antenna as posible, (Iknow you dont have much room in the radio box,,,lol)
Messy cables can generate "Noise".
Its also best to use a Hump pack battery, as they have more Punch and you might be experiencing a Voltage drop at the Failsafe, (although it shouldnt be much, if any).
If all that fails, return the failsafe and get another.
Dont use those Venoms with Temperature capabilities. Ive heard some folks say the are Glitchy, (Just like yours).