The disco has been sitting for a few weeks over the holidays - hooked up to a trickle charger. Finally went to start it up and yeah, I'd get a click, and then immediately the horn would start blaring and the turn signals started flashing. Clearly it's anti-theft related, but why would it randomly decide that someone is trying to steal it?

 

Mine did that recently, but it was not on a charger. Battery was cold and mostly depleted. I went to start the truck and the alarm started, but I couldn't shut it off because the battery was so far down. It kept honking and flashing until there was too little power to do anything at all. Disconnected the battery and let the truck take a nap while I charged it. When I connected the battery again, the alarm went off but now there was enough charge to turn the alarm off.
I figured that the alarm being triggered was a product of the Disco's oversensitivity to battery voltage.

 

Was it locked with hood cracked open? There is a hood switch for the alarm. If not when the voltage gets down low you can certainly see plenty of odd behavior. Usually by securing everything & by either using the remote or key to lock/unlock it the LR alarm system should then work properly.

 

Try jumping it, regardless of being on a trickle charger. Mine would do this when I had a battery going bad and when it got cold it was a crap shoot as to when it would do it and time sitting didn't seem to matter. Also check battery terminal connections.

 

Problem solved - for some reason the trickle charger didn't fully charge the Disco. I think one of the alligator clips on the charger got slightly disengaged when closing the hood. I didn't even notice before starting it what the charge level was. I hooked the charger back up yesterday and left it charging overnight. It was down to under 25% and took all night to get back to 100%. Started like a champ this morning.

I feel dumb.

 

Hey no biggie, important thing is she fired up. In those kind of conditions is usually when I'll find a P1668 fault pending.

My battery charger has stupid clamps as well.