Horn System: Inspection: Trouble Symptom

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

Horn does not sound

Wiring diagram:

Horn system Ref. to WIRING SYSTEM>HORN SYSTEM>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

CHECK FUSE .
Check the horn fuse inside the fuse box. Ref. to HORN>RELAY AND FUSE>INSPECTION>CHECK FUSE

Is the fuse blown out?

Yes : Replace the appropriate fuse.

No : Go to 2.
CHECK HORN RELAY .
Check the relay inside the fuse box. Ref. to HORN>RELAY AND FUSE>INSPECTION>CHECK RELAY

Is the relay OK?

Yes : Go to 3.

No : Replace the horn relay.
CHECK STEERING ROLL CONNECTOR .
Check the steering roll connector. Ref. to AIRBAG SYSTEM>ROLL CONNECTOR>INSPECTION>UNIT INSPECTION>STEERING ROLL CONNECTOR CIRCUIT (EXCEPT FOR AIRBAG CIRCUIT)

Is the steering roll connector OK?

Yes : Go to 4.

No : Replace the steering roll connector. Ref. to AIRBAG SYSTEM>ROLL CONNECTOR
CHECK HORN SWITCH .
Check the horn switch. Ref. to HORN>HORN SWITCH>INSPECTION>CHECK HORN SWITCH

Is the horn switch normal?

Yes : Go to 5.

No : Replace the satellite switch assembly or the driver's airbag module.
- Satellite switch assembly: Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>STEERING WHEEL
- Driver's airbag module: Ref. to AIRBAG SYSTEM>DRIVER'S AIRBAG MODULE
CHECK HORN .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor, perform [Active Test] in [Body Control], and check the horn sound. Ref. to BODY CONTROL (DIAGNOSTICS)>ACTIVE TEST
Does the horn operate properly?

Yes : Go to 6.

No : Go to 7.
CHECK HORN .
1. Turn the ignition switch to OFF.
2. Check the horn assembly. Ref. to HORN>HORN>INSPECTION
Is the horn normal?

Yes : Check the harness and body integrated unit.

No : Replace the horn assembly. Ref. to HORN>HORN
CHECK HARNESS .
1. Remove the steering roll connector. Ref. to AIRBAG SYSTEM>ROLL CONNECTOR>REMOVAL
2. Measure the resistance between the horn relay and steering roll connector.
  Connector & terminal
  
  (B128) No. 1 - Fuse No. 11:
  
  (B127) No. 1 - Fuse No. 12:
Is the resistance less than 10 Ω?

Yes : Check body integrated unit. Ref. to BODY CONTROL (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE

No : Repair or replace the defective part.