That ticking you are hearing is the FICM(Fuel Injection Control Module) warming up the injectors. It basically helps the truck to not misfire due to lack of oil in the injectors and the oil being considerably thicker when it is cold. Your glow plugs wont make any noise themselves. Now, last winter there were a lot of FICMs dying due to the rapid heating of a 24 to 48 volt inverter inside the module. The usual sign was there would be absolutely no ticking at all, and the truck would either stumble, or not start at all. If you would cycle the key enough times, sometimes the injectors would start to work and everything would be fine, until the next cold start after a soak period. Is your truck running fine? The quickest way to tell if you have the latest calibration is to listen to the injector tick. If its just a steady rattle sound, that is the old calibration. If the injectors tick slowly at first and then click more rapidly, that is the new calibration, and you are hearing that inverter warm up more slowly, rather than immediately. It was done to prolong the life of the 24-48 volt inverter. When it dies, there is no tick at all when you cycle the key on.
