I have a 2001 S-type that bought from an impound auction. Had a key made and chip programmed at that time. Car ran super great, no problems. Let sit til I decided what to do with it. Has ran the battery dead several times over the past 2 years and had to get a new key programmed. Every time you try an start it, the alarm goes off. This last locksmith says that it’s in anti-theft mode and nothing he can do. Any advice would be helpful, thanks. (Tried taking it to local Jag dealer, but they won’t work on anything over 6 years old)

 

The Jaguar security system (Ford PATS) is not readily disableable (if that is a word). You will need access to dealer level software to get your issue sorted. You have not indicated where you are located, but a good Jaguar independent shop will have access to the IDS/SDD software needed.

You also should have stopped by the New Members forum and posted a brief "intro," as it is expected and will help you to get full membership privileges on the site. It is also nice to say "hello" prior to commencing to pick out collective brains...

 

i rarely work on early stypes either they’re weird cars

worst case you can buy used pcm + cluster + keys pair and transfer that key’s chip into your old ignition key

 

Before throwing any parts at the issue, test for a parasitic draw when the ignition is in the OFF position.

Also with the ignition OFF, the battery should have a minimum of 12.6 volts available when checked across the terminals with a voltmeter.

 

Will the engine still start? If so, I don't think that's the anti-theft feature kicking it, as it would prevent the engine from starting. In some scenarios, the fuel pump is inhibited, but the starter will still crank as normal. In other scenarios, the starter is also inhibited.

If you're just getting the alarm but it can be silenced with the fob or key in the ignition, that may have to do with low voltage as previously suggested. On my '02, if I have the battery disconnected, the alarm will typically sound when the battery is reconnected. I've learned the hard way to always have the key handy. If that's how your car is behaving, it's very likely due to something running down the battery while parked. If you park for a short time, say under an hour, is the alarm silent? Does it sound only when parked for an extended period? That would be another big clue.

 

One potential problem is if emissions testing is required. Most places read the VIN electronically via the OBD port. If done that way, the reported VIN will not match the physical VIN plate.