2000 F350 PSD 4x4 Having a problem starting the truck, the relay under the dash is clicking like mad. I have changed the batteries and the Glow plug relay without any real changes to the situation. I have inspected the connections and fuses as well but found no problems. I am fairly new to the Diesel enviornment and not sure what the relay under dash is called. I reviewed several pages of history on this subject but all were corrected with the previous changes. I still have the mad relay, is it time to change the relay or is it a problem elsewhere I have still not discovered?
All other functions of the truck are fine, and the relay is intermittent.

Any guidance is appreciated.