Not sure of the 0284 code, but the 0603 code is on most trucks, its a soft code that my truck had too. Soft, meaning it won't trigger a CEL. Now maybe there is a problem with the glow plug relay, i'm not sure if it would have an impact on the WTS light or not. I'm in North Branch, MN so i know what its like to not have glow plugs working. I will try and find some more help for ya one here. There are probably other threads about problems like these.