I have a 96 XJS with the 4.0

I notice when I start my car up in the morning, the horn is non-operational. This happens only when its is a very cold, 32F or below lets call it, morning.

Once the car is driven for awhile, the horn comes back.

Any suggestions?

 

Put a meter on the horn relay to see what side of the circuit is the issue. My guess is thermal expansion is playing a role in whether some contacts are working.

With a meter on the relay, press the horn button and see if the relay gets 12v. If it does, you know the button is working, if not then pop the button out of the wheel and inspect that.

If it does get 12v and still doesn't work, move to the other end of the relay to see if the relay is working and supplying power to the horns, if so, the horns are the issue. If the relay isn't working, replace it.

 

Thanks.

Here's the problem, I don't own a garage and it only happens when it's cold, so I'm not in a motivated state to try to electrically troubleshoot!

It is both buttons, so I don't believe it has something to do with the button(s) themselves.

Thanks. Maybe I'll get inspired someday....

 

Well, if you feel like trying to see if the relay is being affected, stick it in the freezer for a while and then test it on the bench, or swap out the relay for a similar one somewhere else on the car and give the buttons a quick press before running back inside.

 

Most likely the actual horn is getting so cold it cannot vibrate. Might even be freezing in place if it has some water in it.