1994 chevy impala will not start battery is charged

Why do think the key security is bad? If you still have a factory key, this is not the problem...if no factory key, you can take your VIN number or original key to GM dealer to get new key that they will program for you...Check for dirty battery connections:)

Possible alternator issue...let battery charge overnight..or take to Auto-zone Advance etc they check em for free if you can get it there if not charge batt overnite.

you have a shorted battery (have it tested) or there is a loose connection. A starter motor pulls a large amount of current when it engages, a loose conection or shorted battery will all the voltage away from the dash,lights etc.

Relearn procedure--- Turn the key on for ten minutes, turn it off for five seconds. do this three times and after the third time it should start. Just a note... Put a battery charger on it as this procedure will drain the battery.

I'd have to make sure battery has a full charge and battery connections all good. You can use digital multimeter across battery posts, everything off, the generic spec for a full charge is around 12.6 volts. If the battery is down, get it charged up. We can't do any testing if the battery is down.
On further testing, you can take starter motor off, lay it on the ground. Hook up jumper cables properly from charged battery to starter motor, at the least, the starter motor should spin and kick out the drive gear. If it won't do both, then I suspect the starter motor has a problem. I only mentioned the starter motor because you heard a whirring noise, maybe that noise was the starter motor spinning but not engaging the flywheel, for some reason.

If the charge light is not on when you turn the key on before starting then it will not charge.You either need to replace the bulb in the dash or repair the wiring to it.You can get it to charge by running your own keyed power source to the pin in the four prong plug that is marked "L",but if you don't have a volt or amp gauge then you won't know if it's charging or not.

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

Are you reffering to the alarm or the pass lock system that put the theft light on.....If its the alarm the put the key in the door and unlock it. If its the pass lock system put the key in the ignition and turn it on and try to start the vehicle. After it shuts itself off leave the key on for ten min until the theft light stops flashing the turn key off and try to start it again. This may take a few times....

Make sure battery has a full charge and battery connections all good. Any fuses in the diagram, test for voltage, some are hot all the time, some go hot with the key on.
Use a digital multimeter across battery posts, everything off, the generic spec for a full charge is around 12.6 volts. Leave the leads hooked up to battery, have a helper turn key to crank, how far does it drop? In my opinion it shouldn't drop much under 10 volts, I wouldn't argue with 9.6 volts.

If the battery has gone dead, it could cause the security system to go into full lock-up mode. If it has locked up the accessories will work after the battery is charged back up , but the power to the starter will be cut off and it wont turn over. You need to do the 30 minute learn procedure. A GM dealer will print it out for you and you can do it yourself. It's very simple if you follow the procedure exact. hope this helps and good luck.