According to automotivetalk.net it doesn't exist and as I just helped replace one I can concur. The information on that site; replicated below really helped and I had no problem replacing it at all.
by: Bobby
from: AutoWhiz.com relayi am not sure they have a relay for the horn on that one.. i thought that the circuit has a horn, a fuse, then the steering wheel sliding contact, then the airbag.. usually when they stop working, its the horn wire right behind the drivers airbag, it pops out of its connector.Add a message posted: 2004-02-25 01:16:23
On the '96 Sunfire the horn relay is located under the dash behind the glove box. I was able to get to it by removing a small plastic plate held by three screws and reaching up and to the [passenger door] side under/behind the glove box.
where is Horn relay on 1996 buick century.??
The 1994 Pontiac Firebird horn relay switch can be found on the inside of the front quarter panel. The horn relay switch will be on the drivers side quarter panel.
The 1996 Buick Century horn relay switch is located behind the dashboard. The relay switch will be on the drivers side of the dashboard.
See stvndberryhill's answer under 1998 Pontiac Sunfire horn relays. This answer applies to all year models of Pontiac Sunfires.
Did you try the horn relay? It is located near the fuse box.
The horn relay is located in the fuse box of the 1996 Lumina. The fuse box is located under the hood of the car.
Horn relay Horn fuse steering wheel switch
On the core support, drivers side of the radiator.
Horn relay Switches at steering wheel
Check the horn fuse first, followed by the horn relay. If both of these are ok then the horn button or the horn are bad.
The horn relay in 1996 Geo Tracker is located under the left hand side of the instrument panel attached to the CEM. Two green wires connect the power from the fuse to the relay, a blue/green wire connects to the horn and a green/black wire carries power to the horn.
On the firewall to the left of the wiper motor