horn honk with keyless entry lock button

i was wondering if its possible to make the horn honk when i lock the doors with the keyless entry remote. the car is a 96 toyota camry and the door lock wire is: Door Lock      Light Green (-) and the horn is: Horn Wire      GREEN/ Black (-)        Steering Column since they are both negative, could i just hook them both up to the lock wire from teh rs?

yes you could but you need to use a diode because you do not want your door to lock when you honk your horn, but the other way around.2005 Toyota Corolla S

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i thought i found the horn wire today, its the only GREEN/ black wire running down the steering column. but when i tested the wire while pushing the horn its voltage does not change. for a (-) wire does that mean it is grounded when the horn is actually being pushed and should be showing 12v when not being pushed? just want to test it with a multimeter and need to know what values i should see?

i dont' see any voltage on this wire with the keyoff when honk the horn, assuming i don't need key on. but this is the only GREEN/ black wire running down the steering column. i took a picture, it has an arrow pointing to it plugging into a really long connector at the end of the steering column. hoping someone has worked on this model car before and can tell me if this is the right wire/if i'm in the right location?