Alright long time lurker, first time poster.
love these forums, helped me alot with my older 01 s-type that was rearended and wrecked.
Ended up getting a 97 xk8 convertible to replace in February of 2021
no problems at all until I let it sit for a week while I was on vacation, came back, put key in and the car thought it was being stolen so the alarms started going off (much to the charging of my neighbors)
Checked all fuses- okChecked battery, battery was a little weak so just replaced itSLM was corroded, replaced with one off of eBay with same numbers (the last three /006)
Don't believe car is supposed to have a transponder key but have the weird notch in key/fuses for KTM and such labeled in boot fuse box
without SLM the car will start and drive so I can take it to dealer without tow, but it's a bit of a drive so trying to elimate any other options
Think it may be the transponder? If so is that something I can fix or is a trip to the dealer in order as I fear? Thanks In advance guys

 

Disconnect the battery, do a hard reset and then try again. Report back with results.

 

Make sure the battery is FULLY charged. Remember, this is an electric car, no matter what they tell you at the local gas station.

 

Just to clarify a hard reset is leaving it unplugged for 24 hours correct? If so have already tried that after I replaced the battery.

 

I had it on a charger overnight with both the new battery and old battery and then tried it in the morning. I laughed out loud at your statement though because it is very true. 99.9% of my other problems were solved by just charging the battery

 

Sorry that did not help. There is a lot of knowledge here on this forum, maybe others have some ideas.

 

A hard reset is typically defined as disconnecting both battery terminal cables, leaving them disconnected for a couple of minutes, then touching them together for perhaps 60 seconds before re-installing them on the battery terminals. This helps to discharge some of the capacitors in the electrical system and can sometimes work wonders in fixing various electrical problems....

 

Hi - normal behaviour when unlocking using the key is to hear a 'countdown' series of soft beeps to give time to get the key in the ignition & turn to position ii to cancel the alarm sounding. Is this what is happening, or does the alarm sound immediately?

'97 US models don't have a key transponder/KTM, AFAIK. However, you can start the car so if yours is so equipped, it's working fine. Is it just the key remote fob that isn't working?

 

Alarm sounds immediately

AFAIK the 97 models aren't supposed to have it either, and the drivers/owmers manual makes no mention, but the boot fuse box has labels for the fuses.

The car starts only when the SLM is removed, with it in it will turn on the electrics, but won't let me crank- is it possible I just got two bad SLMs in a row? I followed instruction with matching the codes on the boot sticker but it's possible I still messed something up
I really appreciate all the help you guys are offering.

 

Gotcha. Will try this when I get home and update

 

Update to all, tried the steps given here and still no dice, to compound matters if it is the transponder i am SOL unless i can find a dealer that can program a car this old /sigh

 

So you can reach a state with everything connected where the alarm isn't sounding?

Separately, grab yourself a code reader if you don't have one. Even a cheap ELM327 clone paired to an Android/iPhone with Torque Lite is good for starters.

 

negative, alarm sounds the minute the SLM is hooked up- but with no SLM it starts at least

!Did not think to run the OBD reader, already have one and will run/check it tomorrow when I wake up- feel like an idiot for not checking that sooner

 

Did you get any further with this?

Are the symptoms identical irrespective of which SLM is installed?

 

Have not gotten any further, busy couple days at work , symptoms are same.regardless of SLM isntalled

 

Hi,
I don't know if you got any further with this?

You're in a catch-22 since you need to try the fob to cancel the alarm. However, since you've replaced the SLM, the fob won't work until it's paired with the car, which probably won't work during an alarm event. I can't explain why the key-in-ignition doesn't cancel.

The car won't crank with the replacement SLM as the alarm has been triggered, and the trigger state can survive a battery disconnection. From the Vehicle Care Security guide (copy attached):

"
Battery Tampering Alarm and Restart Procedure
This feature prevents the security system from being by-passed by
battery disconnection.
If the battery is disconnected when the security system is either
armed, disarmed or in the full alarm state, the security system will
automatically resume the vehicle state before disconnection
when the battery is reconnected.
"

Did the fob(s) work before this event? Try fitting the original SLM to see if you can regain control with the fob.

Perhaps temporarily disable the horns first to keep the neighbours happy

...and it's always cheap insurance to disconnect the battery before changing any module.


edit: do the remote trunk & gas cap releases work?

 

I haven't got any further with it just yet, the fobs didn't work with the original SLM, but that could have been due to a dead battery in the fob. Tomorrow I will attempt with the old SLM and fresh batteries in the fobs to see if that will help. I disabled the horns the minute I started working on this as it kept going off. Will update you all tomorrow

 

Apologies for the late response. I've been trying to fit all the symptoms together into a plausible scenario..

You're way ahead of me, I see

 

engine cranking control and a ton of other stuff is done by the BPM

you 100% do not have a transponder. a full alarm state is the only way the car will inhibit cranking

 

I do believe that it is in a full alarm state. Trying to use the fobs to unlock or stop it however did nothing. And it doesn't seem to recognize the keys if they're in the door or an ignition. Is there any other way to exit the full alarm state? As a last ditch effort as the fobs never worked since I got the car I'm going to check the fob antenna to make sure it is working