Electrical problem
1999 Mercury Tracer 4 cyl Front Wheel Drive Automatic

Hello I have a 99 tracer that won't turn on. there is no spark and no gas. checked fuel pump and it didn't have any current getting to it.
I plugged an obII code reader and had no codes but then I cranked it and it turned on but as soon as I unplug the code reader it turns off.
It will turn on even if just the obdII code reader's cable is plugged without the actual code reader at the other end. As soon as I unplug the cable it shuts off.
Another thing I noticed was that the check engine light never turns on. I open the key ignition but it still doesn't turn on.
Is it the computer??

thanks
Joe