I just put a brand new engine in my 2004 f-150 4X4. Truck ran fine for two days. Yesterday I started the truck as usual put it in reverse. As I was backing up it just stopped running no warning nothing just stopped. All electrical still working fine guages radio etc. When I turn the key I get nothing no starter nothing. The security light continues to flash slowly even when the key is turned on. Basically the best way I can describe it is. The truck is acting like it is in gear when I turn the key any help would be great. And the odometer reads check guages

 

neutral saftey switch?

 

I had just about the same thing happen to me (going to make a post about it soon). Went out to start the truck and nothing, odometer said check gauges. Don't remember what the security light did. Turned out to be a break in the ground wire for the PCM. If you have a scan tool, plug it into the OBD port and see if is reads anything. When I plugged in my scan tool, it said turn key to the run or on position. So basically the PCM wasn't powering up. The computer actually starts the truck, not the key. The key just sends a signal to the computer to start the truck. In fact you don't need to hold the key to start it, just turn it to the start position for a second and let go, and the engine will contine to crank until it starts.

 

The mechanic pinched my number 6 injector wire in between the manifold. So a thousand dollars worth of dealership so time and problem fixed

 

It sure doesn't work that way on my 04 5.4. , you have to hold the key on until it actually starts