i have a ford focus and when i turn on the head lights the engine cuts out and stops?

Ford. Thats the Problem

Your problems stem from many major or minor factors. Your car is not humanly diagnosable, you must connect a compter interface scan tool to the main computer terminal. The symptoms you are describing can be a host of reasons, and even if the scan tool tells you the item, it does now warrant that the part in question is totally at fault, it could be a corroded connector, vacuum hoses swelled are the port, a sensor. So in your best interest, take your vehicle to someone with a scan tool and at least get the meaning of the code that is present, after your have the car fixed, delete the code from memory or it will only illuminate once again even though the symptom has been repaired.

Your alternator may be dead and not charging the battery... You may have a short circuit in your headlight system somewhere...

EDIT: I forgot to add that you can test the alternator by disconnecting the negative battery cable while the car's running. If the alternator's working properly... the car should continue to run without a battery once started. If the car dies when you remove the cable... the alternator's probably bad.

Maybe it's an electrical problem, or Battery trouble, try

getting the battery recharged and if that don't work then

put it on a diagnostic machine for results they do that

testing at most Auto repair places firestone for example

or Sears, most all places offer that service. Also check

the alternator and/or starter.

I would have the alternator checked.

drive in day time