1997 XJ6 123,000 miles.

I seem to be having a problem with the security system. If the car is locked and I open the trunk with the key, the alarm sounds. Horns blaring, etc. Very embarrassing. Turns off when I unlock the driver's door. Also, possibly related, the battery won't hold a charge more that about ten days. Brand new large battery.

I'm turning the car over to my sister and don't want her to have these problems. I would like to disable the security system.

Removing the 10 amp fuse for the system in the boot also disables the ignition switch so this isn't an option.

 

Trunk manual key release isn’t meant to be used normally. Pretty sure it’s operating as intended.

 

I concur, the trunk key mechanism doesn't have an alarm disable switch. That happened to me too. But only once, in my early days of Jaguar ownership! So the alarm system must be shut off before opening the trunk with the key. That's how it was made....

For sure it is important that Sister knows how to reset a full alarm! It can be reset by putting the key in the ignition and turning it on. Perhaps also by unlocking the driver's door with the key? I've never tried that.

The alarm system and locking system are pretty tightly inter-connected, so I don't know how you would disable the alarm system while still being able to lock and unlock normally using the fob. It is a desirable idea though. But without power door locks it is difficult (and a bit embarrassing) to get other people into the car with you! The Security and Locking Control Module is located behind the fuel filler neck, accessible through the trunk (not easily). One module for both systems! That module interacts with the Body Processor module, so confusion will happen if the SLCM is removed.

For battery longevity I would suggest removing and testing the relays from the 5 fuse box locations. Those are ignition ON relays which feed fuses 10, 12, 14, and 16 in each box. If one of those relays sticks ON when the car is shut off, then some circuits will be incorrectly powered on even when the key is off.

 

My experience is different in that I can open the boot with the key without setting off the alarm but it might be market dependant as mine is a UK car.

Richard has given great advice about the battery drain and you should track that down as if the car has a full battery and goes into shutdown properly it will sit happily for over 5 weeks.

If the alarm is an issue for you could try just disconnecting the plug at the alarm horn just behind the headlights. That would mean you lost the lock/unlock chirp and obviously you wouldn’t notice if someone broke into your car but how many people respond to alarms these days anyway?

Peter

 

Good idea to pull the alarm sounder plug. Maybe also a little clip of the wire that activates the main horns too. Then an alarm state would only be flashing lights.

It is amazing how they built so many market variations into one model of car. And how they decided which market needed what! Apparently they decided the UK cars didn't need security for the trunk (boot), but in the USA both the trunk and the hood (bonnet) were alarmed. Maybe there are more car thieves here? Along the way in 1995 they deleted the hood alarm, but I have lifted my unlatched hood several times with the car locked up and was rudely hit in the face with the Jaguar full alarm state! But I sure wouldn't want one of those cars where thieves could steal your engine and no one would know it....

 

Good info thanks.

I haven't yet bothered to reprogram the two keyfobs, so if I can get those to work then the problem will largely go away.

I was wondering how those relays worked and that makes perfect sense. Odd fuses are always on, evens are ignition-on, triggered by a relay to reduce load of the ignition circuit. It's how I retro-mod old cars by installing an auxiliary panel or panels. Those will be easy to diagnose using the method that you described for the evens, then if necessary jumpers across the individual odd fuses to read with my DC ammeter.

 

I've already tried removing the sounder fuse. All that did was stop the sound signal that tells me that the system is armed. The horn alarm still played its happy tune.

Good advice about snipping the security-to-horn wire. It must be some secondary circuit to the horn relay trigger?

 

I found that the SLCM output to sound the horns in alarm mode comes from the Green with Blue stripe wire, located on connector CA21 which is the largest of the gray connectors on the SLCM. Pin 24. It is spliced into the wire of the same color that comes from the horn switches on the steering wheel, presumably somewhere near the left dash.

I'm going to see if I can remove that wire, set off the alarm and see how it sounds. I think the horns blaring on top of that siren is just too much!