Horn Circuit Troubleshooting
Horn Circuit Troubleshooting
NOTE: SRS components are located in this area. Review the SRS component locations, and precautions and procedures before performing repairs or servicing.

1.
Problem verification:

Problem verification
?1.
Push the horn switch.

Does the horn sound?

     
YES
     
     
     
Intermittent failure, the system is OK at this time. Check for loose or poor connections.?
     
NO
     
     
     
Go to step 2.
2.
Fuse check:

Fuse check
?1.
Check the following fuse.
Fuse
No. B18 (10 A)
Location
Under-hood fuse/relay box

Is the fuse OK?

     
YES
     
     
     
Go to step 3.
     
NO
     
     
     
Replace the fuse, and recheck. If the fuse blows again, repair a short in the No. B18 (10 A) fuse circuit.?
3.
Horn relay check:

Horn relay check
?1.
Remove the horn relay from the under-dash fuse/relay box, and test it.

Is the relay OK?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
Replace the horn relay, then recheck.?
4.
Open wire check (+B HORN line):

Open wire check (+B HORN line)
?1.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Horn relay: disconnected
Test point 1
Horn relay 4P socket No. 2
Test point 2
Body ground
Test point 1
Horn relay 4P socket No. 3
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The +B HORN wire is OK. Go to step 5.
     
NO
     
     
     
Repair an open or high resistance in the wire.?
5.
Determine possible failure area (horn relay switch side circuit, horn relay coil side circuit):

Determine possible failure area (horn relay switch side circuit, horn relay coil side circuit)
?1.
Connect terminals A and B with a jumper wire.

?2.
Connect terminals A and B with a jumper wire.
Terminal A
Horn relay 4P socket No. 1
Terminal B
Horn relay 4P socket No. 2


Does the horn(s) sound?

     
YES
     
     
     
Go to step 6.
     
NO
     
     
     
Go to step 9.
6.
Open wire check (HORN SW line) 1:

Open wire check (HORN SW line) 1
?1.
Remove the driver's airbag assembly.

?2.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Test point 1
Cable reel connector A (20P) No. 2
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
Go to step 7.
     
NO
     
     
     
Repair an open or high resistance in the wire.?
7.
Cable reel check (HORN SW line):

Cable reel check (HORN SW line)
?1.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Test point 1
Cable reel connector C (20P) No. 14
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
Go to step 8.
     
NO
     
     
     
8.
Open wire check (HORN SW line) 2:

Open wire check (HORN SW line) 2
?1.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Test point 1
Horn switch 1P connector No. 1
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
Check the installation of the driver's airbag assembly and the steering wheel. If the horn switch plate is OK, replace the driver's airbag assembly.?
     
NO
     
     
     
Repair an open or high resistance in the wire.?
9.
Open wire check (HORN RLY OUT line):

Open wire check (HORN RLY OUT line)
?1.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Horn relay: disconnected
Horn relay 4P socket No. 1 and No. 2: jumped
Test point 1
Horn 1P connector No. 1
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
Remove the horn, and test it. If the horn is OK, check the horn ground.?
     
NO
     
     
     
Repair an open or high resistance in the wire.?