HELP - horn honks all the time

[PatJ]

My wife has a 2004 limited. Tonight I went out to the car to get something from out of it. I pressed the "unlock" on the keyfob which unlocked the driver's door. I opened the door and grabbed something out of the car. After closing the door I pressed the "lock" button on the keyfob which would normally sound a brief "beep" from the horn. Instead, the horn engaged and hasn't stopped since. It is a constant, solid, horn tone.

The car starts, runs, locks, and unlocks normally. I was able to start the car and pull it in to my garage to lessen the embarrassment with the neighbors while I did my troubleshooting. Once I uncovered the battery, I was able to unhook it and silence the horn. With the battery disconnected, I removed the horn relay under the hood. With the horn relay removed I am able to reconnect the battery without the horn sounding. With the battery reconnected, the horn will immediately sound once the horn relay is inserted.

I have done some testing on the horn relay (which is numbered the same as a normal Bosch-style relay.) The relay is functioning normally and is not stuck closed. The pins from the relay "box" that supply the relay's coil are supplying ~12v. In other words, the relay is simply doing what is told to do and does not appear to be defective.

I have downloaded and read the owners manual from front to back. I did not see anything that would cause the horn to honk constantly and steadily. Does anyone know where this horn relay gets its coil signal from? Does anyone have any guesses as to the problem?

Thanks in advance to anyone that has any suggestions as to what to check. In the meantime I hope she is able to drive the car normally with the horn relay removed.

Thanks again.

Pat

[quicksilverdon]

My guess - the RKEM (Remote Keyless Entry Module) went south. If you read the owners manual, you should be able to program the key fob so that the horn doesn't honk, just lights wink when you lock - but I'll be it won't...
Can you lock & unlock the car with the fob? Do the door locks lock/unlock by themselves?
Based on what you described, the RKEM told the horn to sound and "forgot" to tell it not to...
Good job checking the relay...
The RKEM is above/behind the radio in the center dash.

[PatJ]

Thank you for your reply quicksilverdon

Yes right now (with the horn relay removed) the car works totally normally. The doors lock and unlock with the keyfob and the interior switch normally. My wife was able to drive the car to work and back without any problems. Everything is the same as before - except if I try and insert the horn relay I can feel the relay tick and the horn immediately sounds.

I will do some more research in to the RKEM. Is there a way it can be "reset?" Thanks again for your help.

Pat

[quicksilverdon]

You can try taking the positive cable off the battery for a few minutes. That resets everything.

[CREWZIN]

Here's a thread to read, might help.......

Radio and Horn