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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Check the fuse?
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
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
Inproper polarity on horn wires. or horn relay bad. Ensure voltage (12VDC) on horn wire when activating horn. If nothing... suspect relay.
Short in the wiring with the steering column.