Check FICM Voltage
You are running late for work. You go outside, place the key in the engine, and nothing happens. No matter how many times you turn the key to start, the engine won't turn over when it is cold. You don't know what the problem could be.
Well, one problem may involve the Fuel Injection Control Module (FICM). The FICM has a voltage of 48 volts as it fires the injectors. If the voltage falls too low, the injectors will not fire. You can perform a FICM check to see how much voltage it has.
Checking the FICM
It's best to check the FICM when the engine is cold and you have someone who can help. You should move the coolant reservoir to give you room. You don't have to fully disconnect the hoses. Just remove the two bolts holding the reservoir to the cowl and push it to the side.
Remove the two screws on the lid of the FICM and take it off. When you look inside, you will either see 4 screw heads or 7 screw heads depending on the year your truck was manufactured. With a multi-meter, set it to DC volts and place it on the far right screw if there are only 4 screw heads. When testing 7 screw heads, place the multi-meter on the screw on the far left in the top row of four screws. Never allow the multi-meter's probe touch the case.
Have your assistant turn the engine key without starting the vehicle up. With the key ON, test the voltage. If the voltage is 46 or more, the FICM is fine. If it ever drops below 36, then something is seriously wrong with your FICM.
Tell your assistant to cycle the key as you continue to check the voltage during the key-on buzz test, it should not drop below 46 volts. Turn over the engine and check to see if the FICM maintains its voltage. If it does, your FICM is fine and you can troubleshoot other areas to determine the engine problem.