My horn on my 2003 sebring limited will not work, it sounds when you use the remote to lock the car but not when you depress the horn on the stering wheel. The fuse looks good what else should I check?

Do you have an air bag light lit on the instrument cluster ? Do you have C.C. button's on the steering wheel , do they work ? If the alarm fob (as u call it ) Can make the horns sound , the relay is sending B+ voltage to the horns Don't know how your testing.
System Description
The horn system consists of the following components:
• Horn fuse
• Horn relay
• Horn switch
• Horn(s)
• Body Control Module (BCM)
System Operation
The vehicle horns are activated under the following conditions:
• The horn switch is depressed.
• The body control module (BCM) commands the horns on. The BCM commands the horns on under either of the following conditions:
- When the content theft deterrent system detects a vehicle intrusion. For further information, refer to Content Theft Deterrent (CTD) Description and Operation in Theft Deterrent.
- When the panic button is depressed on the remote control door lock transmitter. For further information, refer to Keyless Entry System Description and Operation in Keyless Entry.
- When the OnStar® system is used to sound the horns, if equipped. For further information, refer to OnStar Description and Operation in Cellular Communications.
- When the keyless entry system is used to lock the vehicle, a horn chirp may sound to notify the driver that the vehicle has been locked. The notification feature may be enabled or disabled through personalization. For further information, refer to Keyless Entry System Description and Operation in Keyless Entry.

Circuit Operation
Battery positive voltage is applied at all times to the horn relay coil and the horn relay switch. Pressing the horn switch applies ground to the horn relay control circuit. The body control module BCM may also apply ground to the horn relay control circuit as described above. When the horn relay control circuit is grounded, the horn relay is energized and battery positive voltage is applied to the horn(s) through the horn control circuit. The horn(s) sound as long as ground is applied to the horn relay control circuit.

The vehicle horns are activated under the following conditions:
?€¢
The horn switch is depressed.

?€¢
The body control module (BCM) commands the horns on. The BCM commands the horns on under either of the following conditions:

-
When the content theft deterrent system detects a vehicle intrusion. For further information, refer to Content Theft Deterrent (CTD) Description and Operation in Theft Deterrent.

-
When the panic button is depressed on the remote control door lock transmitter. For further information, refer to Keyless Entry System Description and Operation in Keyless Entry.

-
When the OnStar?® system is used to sound the horns, if equipped. For further information, refer to OnStar Description and Operation in Cellular Communications.

-
When the keyless entry system is used to lock the vehicle, a horn chirp may sound to notify the driver that the vehicle has been locked. The notification feature may be enabled or disabled through personalization. For further information, refer to Keyless Entry System Description and Operation in Keyless Entry

System Description
The horn system consists of the following components:
?€¢
HORN fuse

?€¢
Horn relay

?€¢
Horn slip ring

?€¢
Horn switch

?€¢
Horn assembly

?€¢
Body Control Module (BCM)

System Operation
The vehicle horn system is activated under the following conditions:
?€¢
The horn switch is depressed.

?€¢
The body control module (BCM) commands the horns on. The BCM commands the horns on under any of the following conditions:

-
When the panic button is depressed on the remote control door lock transmitter. For further information refer to Keyless Entry System Description and Operation .

-
When the keyless entry system is used to lock the vehicle, a horn chirp may sound to notify the driver that the vehicle has been locked. The notification feature may be enabled or disabled through personalization. For further information refer to Keyless Entry System Description and Operation .

check for power to the horn relay. also check for signal to the relay from the steering wheel contact buttons. if all is good then must be a bad horn.

That is the security system coming on.

Have you checked if there are any mega fuses that went, maybe a shorted harness or bad relay?

Did you read the requirements for your particular system? The reason I ask is most remote starters will not work on a vehicle with a manual transmission, because of thier need to have the clutch pedal depressed in order to engage the starter.

sounds like only 1 of your 2 horns is working - up under hood near center in frt of radiator-or on 1 side down in front by wheel well horns are located

Don't see how one would blow the fuse an not the other . The remote function is controlled by the BCM - body control module or vehicle interface . Regardless ,the module an the switch on the steering wheel both energize the horn relay ! Do you know what a relay is an how it works ?
Check the horn relay

VEHICLE RELAYS Operation Diagnosis

check all fuse are normal , if damage change it first other wise
you have reprograme the remote with car or change the door control switch