1. Disconnect the negative battery cable..
2. Remove the front bumper..
3. Remove the horn..
4. Apply battery positive voltage to horn terminal A, and connect the horn retaining bolt to ground as shown in the figure, and then verify that the horn sounds.

If the horn does not sound, replace the horn.
Horn
Horn Removal/InstallationController Area Network (Can)
Outline
The DSC HU/CM sends and receives data to and from other modules via the CAN
system. Refer to MULTIPLEX COMMUNICATION SYSTEM for a detailed explanation of
the CAN system..
Data sent
Cruise control system-related information
DSC system-related information
...
Multiplex Communication System
A controller area network (CAN) system has been adopted in which multiplex
communication is performed using a single communication path.
A high-speed controller area network (HS-CAN) has been adopted for the communication
between the following modules:
PCM
...
Speaker [Without Bose®]
Purpose
Converts the audio signal from the audio unit to sound.
Function
Full-range speakers, which can output wide-range sound from low to high frequency,
have been adopted.
Specification
Item
Front door speaker
Rear speaker ...