2000 alero will not start

2000 alero will not start. ran fine last night, this am would not start. I have spark and fuel. my security light sometimes stays on when key is on the on postion, and sometimes it goes off. I have switched fuel relays no help. does anyone have a idea?? If not it goes to the shop and I drive my 69 mustang to work. help please

If you have spark and fuel, you should have combustion, but you never know with these cars. When mine didnt start it was because of a bad fuel pump. Sometimes a bad engine coil caused it not to get a spark on other occasions. But this probably doesn't help you any because you sdaid you had fuel and spark...

but a bad spark plug or coil may be providing spark just not a strong enough spark

mine did the same thing the other day, the positive post broke away from the battery. loosen your cables from the battery, then check your post. yours may have done the same. these batteries have a bad rap.

if your security light came on, turn the key to the on position and leave it on for about 10 minutes. This will allow your pass-key system to re-learn the key and the car should start. Also, clean the metal contacts in the chip in the key with a pencil eraser to get any oils and dirt off it so it will read proper resistance.