'00 S-type V8.

Had a battery issue, got a new one, and once reconnected, the alarm will start and go off once the key is in the ignition, but other than that, the car acts as if it is 100% dead.

For the purpose of thorough details, and maybe a possible fix, after reconnecting I close the trunk. All doors are locked as of that time, and when the drivers door is unlocked, that is when the alarm sounds. Is there maybe some sort of way to "trick" the alarm in this scenario?

Thanks in advance!

(I did search thoroughly but was not able to find anything)

 

I believe all the S-Types sound the alarm if you unlock the drivers door with the key and continue until you cancel the alarm (key in ignition or use fob). The reason is that the door is essentially a mechanical thing (angles cut into the key) but the alarm wants to see a valid security code (which it gets if you press the fob or put the key in the ignition).

This should not have changed due to a replaced battery.

No, it can't be bypassed as it's a decentralised system spread across multiple modules connected via computer buses. (Well, if you create your own modules and pass the right packets over the bus, but by far more work than it's worth...)

If it now won't start, watch the PATS light as you try to start the car and for the next minute or so. If it's a security issue it will flash a code.

 

Thanks for the reply, I was able to reconnect the battery and get in (lights on etc.) and put the key in the ignition without the alarm sounding. When I put the key in the ignition the steering wheel comes out like normal, but as soon as I turn the key, the battery acts as if it's dead. The steering wheel stays in its spot and all the lights go off and whatnot.

This time after getting the battery reconnected and closing the trunk, the door was locked to start. I unlocked, relocked, and the unlocked again based off of some things I have read that worked for others, but apparently not for me. Is there something else I should be trying here?

 

Sounds like still no or very little power.

So... back to the battery etc. Is it a second bad one? (Does happen.) Too poor spec? Is there a wiring problem? Any damp/water in trunk (remove spare). Etc....

 

Ditto to Jagv8. Touch the pos. and neg terimanls together for 30 seconds then reattach to battery.

 

Follow JagV8's advice. What is the PATS light doing on the dash? I think the car still is not happy with the security.
.
.
.