I recently got a used 2005 Cadillac Deville. It honked the horn when locking using the remote. Yesterday I picked it up from a mechanic and now it no longer honks on lock. He says he didn't change it. How do I reset the function?

What was the mechanic doing to it?

Does it still lock, and just not sound the horn?

Does the horn work other times?

How many miles on it?

What region does it live in?

Do you know any history on it from before you bought it?

Three weeks after having an "AAA advertised Pre-Road Trip Oil Change and 40 point inspection."
A drive of about 25 minutes, mostly up hill, (elevation change of 2500 ft.)in 105 deg. F. heat to the desert north of Los Angeles. Once I got onto the flat land. And into the housing tract the (oil can) warning light came on and the information screen read "Low Oil Pressure" Stop Engine" which I did Immediately. After towing the car to the shop. The replacement of oil pressure sensor and oil level sensor. The mechanic also (at my request to eliminate a steering wheel vibration / shaking at 65 - 70 mph) replaced front hub and bearings.
There was also a code of P0496 found during the diagnostic portion of the repair which required the replacement of the Evaporative emissions systems purge solenoid.
I have only owned the car for about 7 months.
The 2005 Cadillac DeVille Has 120,765 miles. It is the base model with a 4.6 liter V8 (Northstar) FWD, Automatic Trans
There were no service documents or history on the car that is reliable. It has had 3 previous owners.

Well, after some additional research. I've found some programming / reprogramming instructions on Chilton'* Online via my local Library'* Articles and Databases.

If one minute it honks and then it doesn't, it could also be a sign of a weak remote battery, or poor contact at remote battery.
With my Buick you hold down the lock and unlock buttons for 8 seconds simultaneously, to re-synchronize.
The remote programming options descriptions will be in your owners manual as well.
Take some time and familiarize yourself with your owners manual which can be found here in pdf format, if you do not have the owners manual.
https://my.cadillac.com/content/dam/...lle_owners.pdf

My questions and thoughts:

This is important, save for later.

So . . . like from Sylmar or Sand Canyon to Palmdale/Lancaster, right? I may or may not have spent a lot of time in that area.

About all that'* left there any more.

Did you hear any bad noises when this happened?

Did you check oil level while waiting for the tow truck?

Still wondering about the oil level before the mechanic touched it.

Also, how was the drain plug?

This is related to the "Save for later" above. I am wondering if AAA tech left the drain plug loose.

. . . and wondering why the oil level sensor was replaced. Low oil pressure sensor is easy(ish) to replace, and is directly related to the symptom. Oil level sensor is unrelated unless it was out of oil and didn't tell you.

. . . and confirming that this fixed the vibration/shaking issue?

This sounds like a good repair.

Woohoo! Give it a shot!

There are still libraries???

Still looking for answers for: