Hi, Lionel, this is Ed. Welcome to JustAnswer!.
Use a test light (preferred) or a voltmeter to test for voltage at Fuse M25 in the underhood fuse and relay center, called the TIPM. M25 is your fuel pump relay output circuit, a good place to test for relay feed when you've just rolled the key to ON or are cranking the engine. Fuel pump relays are becoming a more common source of problems of this sort, especially in the 2011 model year.
If the truck refuses to die for you (on command), have someone roll the ignition key ON repeatedly as you listen for the distinctive <click> from the relay while probing the M25 fuse. Power should arrive at the same moment that the click is heard, so if you notice a lag in timing between click-light, it's a positive sign that the fuel pump relay is compromised. Given enough attempts, you may see a cycle when the click happens, but no power is transferred to the fuse. Tests lights tend to give me better feedback than the rather slow update rate of a digital voltmeter, plus the intensity of the bulb is a good indicator for strength of the electrical signal. You can probe the fuse from either of the test tabs -- no difference.
If the relay output is found to be weak or absent, repair involves replacement of the entire TIPM unit, fuses and all. The fuel pump relay is hard-soldered into a circuit board below-deck and isn't serviced outside of the entire TIPM unit. A new TIPM auto-configures to your truck with a simple 10 second key-on of the ignition switch with (perhaps) a tire size rating that may need to be changed by the dealer if you've changed sizes from what's shown on the door label. Your speedo/ odometer will be off just a bit until the new tire size is input if that's the case.
TIPMs cost around $750, but can be replaced at home if you'd be interested in tackling it yourself.