If you connected the cable box with a single antenna cable to the antenna input of the TV your TV has to have an analog TV tuner to find the channel 3 or 4 output.
If you connected the cable box with AV cables you don't need to run a channel scan. Just select the input you connected the box to. Use HDMI if you can as you won't get HD with AV or RF connections.
You will get much better picture if you connect TV to the box using RCA (white/red, yellow) or HDMI cable. For coax connection, your TV should be probably set to channel 3 or 4 (check with cablebox' documentation).
If you connected the cable box with a single antenna cable to the antenna input of the TV your TV has to have an analog TV tuner to find the channel 3 or 4 output.
If you connected the cable box with AV cables you don't need to run a channel scan. Just select the input you connected the box to. Use HDMI if you can as you won't get HD with AV or RF connections.