Okay I will attempt to keep this in clear steps
Bought car with no history, no key, car sat for at least 2 years
brought home on trailer, had key made
charged battery for few hours car started
Obvious fuel issue due to exhaust smell
ran some additives thru and car started and drove decently but would not start again untilnput on charger
pulled aftermarket alarm
Drove car four hour but when i turned it off no restart next morning
Got larger battery from a friend when plugged it in to jump pack a new alarm went off (original)
since then soon as I connect the negative posts to battery after charging it. The alarm goes off and with no key fob I run to put key in ignition it tries to start but stalls then I have to run to trunk and disconnect battery before my neighbors start throwing things at me.
I'm at a lost . I've searched for ways to disconnect horn. No luck. I've taken battery to garage and had them charge it. Soon as I get it back to car and install no power. I plug jump pack to it. And alarm goes off . Yes I need a brand new battery but I want to see if its bad before I replace multimeter shows 13.5 with battery outside of vehicle

 

Hi Dakico, the horn can be disconnected by pulling the relay that is situated directly behind the drivers side headlight. When you open the hood, there is usually a cover with labels showing the horn relay. Just pull it out and the horn will stop. If it is the alarm speaker, the horn on my XJ6 is on the passenger side behind the passenger side headlight. There are two wires that plug into it. Pulling one out of the connector will also render it mute. I know that having the correct battery for the car is always crucial so I would start with that first. Others will chime in I am sure with more information. Good luck!

 

Thank you so much I'm getting battery charged as we speak, I will look at relay when I get back to the house. Is the speaker a silver fuel filter looking peace with a rubber cone on it It... looked like it could be the alarm speaker siren of death

 

Hi, if you look under your center armrest there should be a switch to turn the security system off. It will be at the rear by the hinge. Mine has a trunk release and a security switch there.

 

So we disconnected all 3 horns so we could survive charging the battery and she finally started after much starter fluid...again it's been sitting for 2 years if not more..

I turned Security switch to off position...voltage reader shows 13+, alternator is good so next job is replacr fuel get oil changed and to maybe plug horns back in and see if alarm stays off