Did you try the horn relay? It is located near the fuse box.
right next to the emergency flasher It is a white three prong connector
The horn relay on a 2003 Pontiac Sunfire is typically located in the under-hood fuse box. You can find this fuse box near the battery on the driver's side of the engine compartment. The horn relay is usually labeled on the inside cover of the fuse box, making it easier to identify. If you're troubleshooting the horn, it's a good idea to check this relay first.
Horn relay Switches at steering wheel
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.
See stvndberryhill's answer under 1998 Pontiac Sunfire horn relays. This answer applies to all year models of Pontiac Sunfires.
The horn relay on a 1998 Pontiac Sunfire is located in the engine compartment, specifically in the fuse and relay box. This box is typically found near the battery, on the driver's side of the vehicle. You can identify the horn relay by consulting the diagram on the cover of the fuse box, which indicates the specific location of each relay.
The horn is located on the driver side of the engine, real close to the battery. No. It's on the passenger side next to the rad.
Should be in front of the radiator on either side. To easily find it, have a friend honk the horn while you find the source of the sound.
Horn relay Horn fuse steering wheel switch
On the core support, drivers side of the radiator.
The horn is located on the front of the radiator bulkhead, to the right of the rightside frame member, below the right headlight assembly. You can access it from below the bumper.