Anti theft activated-now car won't start and radio won't work. Radio won't take radio code and car cranks but doesn't start, horn blares, and headlights flash. I don't have the other code for the anti theft but do have the radio code. How do I get the other one and how do I set it??

Has the battery died or been changed or unhooked. I know some car radio if they loose battery power, they quit working till you put a radio code in them.

with the battery dying the radio and equipment that has anti theft circuits have had the anti theft codes activated . You will need a code for the radio before it will work again and for anything else may be a reset of the CPU using a scanner will be the answer.

Check owners manual. If none go to dealer for the code.

you have 1 of 2 choices ... anytime you take out the factory radio it activates the anti theft and car will not start choice 1 is put back in factory radio .. 2 is you will have to take it to a dealer to reprogram the radio to the anti theft modual the newer cars with antitheft will not start without it being reprogrammed by a dealer when taking out and exchanging radio

If it does not crank, it could be a bad connection between the battery and starter, a faulty neutral safety switch, anti-theft system problem, or a faulty key switch. Not to mention a faulty starter.
If it cranks but does not start, you would need to know if it has spark, fuel, and normal compression.

When you disconnect your battery and then reconnect it again, it disables the radio. This is an anti-theft protection for your car radio.
The enable your radio the activation code is in your vehicle owner's manual. If you do not have this code you need to go to your Honda service centre and get them to enter this code for you.

Check the help links mentioned below :---Relearn Theft deterrent module? http://technoanswers.blogspot.com/2012/01/relearn-theft-deterrent-module.html
---------theft deterrent module Relearning? http://howtobyme.blogspot.com/2012/01/buick-theft-deterrent-module-relearning.html
--------Engine will not crank after relearning Theft deterrent module? http://howtobyme.blogspot.com/2012/01/engine-will-not-crank-after-relearning.html
--------Can car radio code block Passkey anti theft system ?

http://schematicsdiagram.blogspot.com/2011/12/can-car-radio-code-block-passkey-anti.html
Car Factory Alarm will go off? http://repairhelpcenter.blogspot.com/2012/01/toyota-avalon-factory-alarm-will-go-off.html
---------Car will not start security lock out? http://technoanswers.blogspot.com/2011/12/car-will-not-start-security-lock-out.html
---------Alarm will not disengage? http://technoanswers.blogspot.com/2012/01/ford-pickup-alarm-will-not-disengage.html
--------This will help.For more info keep updated.Thanks.

It's possible that you will need assistance from the manufacturer of the Anti Theft device. They may have tto reset the system, as an Anti theft device, any thing construed as 'tampering' with the car, or the device may cause it to shut down, and would need tech support from the manufacturer.

it is most likely that the radio had an anti theft security code activated & until you re activate the code the radio will not work......hope this helps.......cheers.

by disconnecting the battery you have activated the anti-theft system in the radio
you will now need a code and insert it in the radio before it will operate again