When I turn the key on without starting the truck, I hear the lift pump on my 2004.5 humming away. But I also hear a steady ticking sound coming from the valve cover area that continues after fuel pressure builds up and the lift pump stops. I haven't gotten around to isolating the ticking yet but am making a preliminary guess wondering if it's fuel system/pressure related. Injector?

Truck has 78,000+ miles on it and never had any problems. Maintained religiously.

 

my 07 does the same thing, its done it since new, i wouldn't worry about it

 

You may be hearing the grid heater relay.
Topper

 

my truck has been doing that since new, IMO I think its a injector bleeding the system perhaps, I wouldn't worry about it

 

its the grid heater.