My '06 TL has spent most of its life in the warm Southeast. Currently in Colorado Springs, the horn started blowing continuously in the wee hours of the morning while parked outside in 6 degree temp at a rented condo. The neighbors and subsequently, the police were not amused. This was not the alarm as the horn was blowing continuously and the lights were not flashing. Pressing the steering wheel would momentarily silence the horn but it would start back after a few seconds. Had to disconnect the battery to silence the horn. Reconnected the battery several hours later when it was nearly 30 degrees and everything was OK. Any ideas? Don't want to have to take the horn fuse out every night. Also, where is the horn relay located?

 

Check you PM inbox. Could be the relay, horn switch or cable reel.

 

Ill bet its the horn relay - old relays have a tendency to 'hang-up' in the closed position when they are NO (normally open).