What do you mean by HD plugins? There should be a composite, S-Video, component and/or HDMI input. Doesn't matter which input you use it wouldn't just sent black and white signals. So there must be something wrong with your TV or maybe even defective Wii video cable.
If you are seeing only black and white, it means one of two things:
1) You are using a component output on the Wii, and connecting the "Y" cable to a composite input on your television. A component signal requires three RCA plugs at the TV as the Y signal is only black & white plus clocking, while the other two cables carry the chrominance and luminance information
2) You are using a composite output on the Wii, and are connecting the cable to the component Y input on the television. The television will ignore the colour burst information in the composite signal, as it's not expecting such information on a component input.
Check your user manual and ensure that you are using the right cable/connector combo.
