I have a 1999 Ford F150 you have to have the dome light on for it to Run. if the dome light is off the motor just cranks over there's a relay clicking in the fuse box also. I replace the gem box. And it did the same thing. Now replace the computer and security lights blinking and won't let me go any further to start it. Anyone have any ideas

 

If you replaced the computer, you have to get the dealer to flash it with your VIN and PATS.