Manifold Heater
 

On cold days, the wait to start light flashes rapidly and eventually goes solid before shutting off. I can hear i assume a relay clicking rapidly? is that normal?

No.
You may have a faulty temp sensor.

It's supposed to come on solid below 50* and go out once the manifold temp rises above that temperature.
It will then cycle the grid heaters once the engine is running until the engine is warmed.

Mark.

Mark.