More than likely a stuck horn relay.
Because the other one is damaged. Usually water damage.
any horn will work from the junkyard.
On the passenger side below the headlight assembly, behind the bumper cover, accessable from the bottom.
take it to a car shop and tell them you need a new horn.
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In the Upper Fuse Block, on the passenger side, in the engine compartment...
under the hood pasenger side front in between battery and head lamp
If a 1987 Chevy Suburban has lights and horn, but no ignition, gauges, radio, or interior lights it could be a ground wire problem. It is possible that there is a short somewhere. Also check the dome light for a possible water leak in the headliner.
Begin by removing the wiring harness from your 2005 Chevrolet Impala horn. Remove the horn retaining bolts. The horn will come off.
# 8 15 A
If you have a POLICE PACKAGE Impala ...some time the cut the wire who activate the horn ..they send it to there police equipment , because they can shif the steering "horn" ...if they press a button on ther computer it gonna be the police siren goes on when the press horn. and inverse, the switch it to use the regular horn...that's coulb be a possibylity IF IT IS NOT A POLICE PACKAGE some time the horn goes bad because of water going in the horn in the front