2000 z24 check engine light steady on

engine lopes while idling and the cooling fan is operating at startup (cold) with ac and defrost off. i read some quotes about engine misfiring, maybe it is ecm problem. can you tell where the ecm locates? or do you have any other idea about my car's problem?

yea figure out what the check engine code is saying

the newer cavaliers have crappy electrnics systems, buy a gm code reader and plug it into your adapter under ur dash and click ur key ahead, but do not start it. You will see your check engine light blink if there is no error codes, take your battery wires off and put them back on after ten minutes then it will reset the computer.