Car doesn't start, security light goes on, if I wa...

This may work:
turn key on. Leave on for 10 minutes. Turn key iff. Turn back on. Wait until security light goes off. Then start car.

The only way to reset a computer is to take it to a dealer they have the codes needed to do this

Is the security light flashing? If so, turn ignition on and wait for 10 minutes and light should stay on solid. Then try and start the car without turning the ignition back off. Then turn off ignition and wait 1 minute. Then turn ignition on and see if security light is flashing. If not try and start your car. If it is flashing, try waiting again with just the ignition on and see if it goes out.

try a different key, the light will come on and stay on if the tumbler is not reading the resistor in the ignition key.
if that doesn't work try to start car, then don't turn key off leave it in on position for about 10 until the security light goes out, turn key off then try to start again.

Hello: TRY THIS Attempt to start the car leave the key on for 10 minutes or until the security light goes out, at this time turn key off for 10 seconds, turn switch on for ten more minutes or when security light goes out, turn key off for 10 seconds. Turn key ON for ten minutes or when security light goes out, turn key off wait 10 seconds, then start car....

Hi, if you are receiving a u1040 code ,the car needs to be put on a good scanner to see which module is not communicating this includes the pcm-ebcm-bcm-sir/sdm-ipc-radio and the pass key 111, you need to check the battery hots, ignition hots ,grounds and serial data lines to each module if the scanner cannot communicate with any of the modules, the serial data line will have a very low amount of voltage and will be moving between low voltages check all the fuses and relays battery connections and grounds, the ignition relay is a good one to check, also for the antitheft reprogram relearn there is a 30 minute relearn process ;;try to start the vehicle and release the key do not turn it off wait ten minutes until the security light goes out then turn the key off for 5 seconds and turn the key back on wait 10 more minutes for the light to go off again turn the key off for 5 seconds and then back on for 10 minutes more after the light goes off turn the key off for 5 seconds and now try to start the car, if it still doesn’t start then check for any connections under the hood for water damage or critter damage.

Take care

did your old cylinder have wires coming out of it ? did your old key have a chip in it is your security light on? if so the vechicle 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

the key barrel contacts are probably worn this will need a new lock set

try another key. if this doesnt work the wire in the tumbler assembly most likely broke and you will need it replaced. ( Ignition Switch)