Ok i have a 2003 chevy monte carlo 3.4 my doom light visor lights and rear view mirror lights have stopped working completely and this morning my signal lights quit. The security light comes on and sometimes my car will not start. Radio shows locked sometimes and also my a/c quit. I was told its a key problem and since the only key i have is a made key (came wit the car dealer doesnt have original key he also said that the ignition has not been replaced) my ? is, will going to the dealer and getting a new key fix my prob, get a new switch

SOURCE: 1998 monte carlo brake lights

I have the same problem,it's the switch inside the turn signal assembly.Unfortunately the entire assembly switch and all has to be replaced.
Hope this helps.

SOURCE: 97 Chevy Monte Carlo won't start, security light is on

disconnect battery for 24 hrs so the computer will reset and if that dont work take it to chevy dealer and have them reset it manually

SOURCE: Signals and Four Way Flasher working intermittently

Replace the hazard switch, It has the turn signal flasher built in to it.

SOURCE: 2001 Monte Carlo SS Stalls while driving

its your M.A.F thats the air flow sincer i had that problem also but as soon as i got a new 1 it stopped and ran fine. the part cost about 160 bucks at auto zone and is easy to take off and put on yourself cuz the shop charge about 300 bucks to do a 3 min job but im sure that is the problem with your car

SOURCE: Replaced ignition switch 2003 chevy impala and car will not start

After you replace the ignition switch turn the key to start the car and release leave the key were it stops after trying to start wait 10 minutes until security light goes out turn key to full off position then repeat the above procedure two more times for a total of three on the 3rd attempt to start car wait for light to go out then turn key to full off positoion wait 10 seconds then try to start car body control module should learn new pass code and the car should start.
Big john, J@J Automotive