Hi everyone,
I am new to the forum and would appreciate any suggestions on how to make my horn work when remotely locking the car (xk8, 2001, 120k miles.)
thanks!

kkxk8

 

Not an easy one to diagnose, as there are different systems according to model / market etc.
Assuming you mean the little "chirrup" - it comes from a little security sounder just behind the headlight on the right hand side wing. It may be "passive" or "intelligent" depending on whether it is also linked to "tilt sensors" and other stuff. Worth checking Fuse 9 (10 amp) in the engine bay fuse box - if you're lucky, that might be the problem. Otherwise, the most common problem is that there are two rechargeable NiCad batteries in the sounder which, after many years, corrode and do this :



It is possible to sort-of dig them out of the rubberised potting compound and replace with new, but it's not a straightforward job. Or ............ replace the whole sounder unit with new, but that won't come cheap !! You can look at the wiring diagram on Gus's site :
www.jagrepair.com, under "security and locking". 13.2 if my memory serves !!

 

I also have a 2001 and on my car it is not the horn that sounds off when remotely locking the car, as it is with most every other car. The fact of the matter is that it is a very low chirp that you can't even hear if you are not near the car. Stand right up close to the car and see if you can hear it. If not, then you will want to follow the suggestions of Devon David.

 

Thanks for the photo. What is Jaguar thinking? Quite a job to excavate the batteries and replace them. Why did Jaguar not use a 12V sounder?

 

John S - They did !! It's just that if a thief manages to get into the trunk (boot) to disconnect the battery to silence the alarm, the rechargeable cells in the "security sounder" will keep the alarm sounding.
It's quite a complicated circuit :



If everything is working properly, it "recharges" once the ignition is on, and is "primed" by the locking circuit. What can also happen, is that the two NiCads corrode and stop working, thus providing a constant current drain on the battery which is frequently the cause of a low battery after a period of not using the car.
Mine stopped working, I tried to replace the NiCads but the rest of the circuit had also stopped working, so I replaced the unit with a second-hand one. Everything is "potted" in a sort-of rubber compound, so it's difficult to dig out. In theory, it should be 100% waterproof, but it's in a very vulnerable position, so the tiniest bit of water getting in by capillary action starts the corrosion, which then just gets worse !

Edit : In some countries, a "passive" sounder is fitted, which doesn't have an internal power supply, and is much less complicated. I think the only way to be sure is to disconnect the plug to the sounder under the front wing and see how many wires there are, with reference to the wiring diagram.

 

Further to above .......

Wiring diagram :



Your car will have EITHER the passive sounder OR the active sounder - not both. If two wires, the former, if 4 wires, the latter.

 

What I can't understand is with those batteries so badly corroded, why on earth didn't the security module throw a complete wobbly and send a message to the transmission module to tell it to stop working, send another message to the engine ECM causing it to throw a whole multitude of error codes causing a 'Restricted Performance' message whilst simultaneously saying 'Trac Not Avail' and 'ASC Not Avail' and of course locking the boot and fuel filler flap that can only be opened using a dealer level scan tool
Or am I getting a touch cynical in my old age?

Andy

 

I prefer mine not working as I think they are annoying. The lights flashing to confirm lock/unlock is good enough for me,


Dave

 

Apology and correction ................. it's some time since I did mine, so memory is a bit fuzzy (or is that old age ??).
I think Jaguar used the same loom for both types, so there will probably be six wires on the plug irrespective of whether active or passive. The label and part number on the sounder will confirm which type you have.

 

Thank you so much! Great information, though I suspect the fix will be difficult.
Thank you!

 

Thanks. Unfortunately, my lights stopped working now too....

 

My lights stopped working now as well. The only thing I hear is the locking mechanism. I wish I could at least get the lights to work.

 

Have your tried it with the Key only?
Insert and turn counter-clockwise (anti-clockwise), you might also want to perform a hard reset, just a couple things to try before you replace the sender/battery unit?

 

VERY helpful info on the passive sounder.
Question...If one wanted to add a passive sounder on a different make and model auto, what would the two wire (wu & wb) wires get supplied from?
Any help would be appreciated.
Ed

 

And also, which two of the six terminals are used?
thank you again, Ed

 

alcoed - not sure that what you are suggesting is a practical proposition. My guess is that the BPM (Body Processor Module) is the same in both cases (passive or 'intelligent' sounder) It may be that it has to be programmed - don't know.
I can't see how it could work on a different make and model as the BPM is Jaguar specific. But ........... I'm no electronics / electrics expert, so maybe someone else has a more experienced view of this.

 

Looking at the wiring diagram, it appears the 'sounder' gets a simple 12volt + &- feed.
I understand that it may need a module for intelligent timing, but a generic alarm would 'tell' it when to sound off. I could be wrong but doesn't this make sense ?
Ed

 

You may well be correct. I have no idea what is inside the "passive" sounder. The two NiCads in series would give 3 volts, and the "active" sounder is designed to work if the car's 12v battery is disconnected, so my guess would be that it is more likely to work with 3v+ & ground, rather than 12v+ and ground. I can't think that the actual "sounder" module (i.e. the bit that makes the noise) is different for 'active' and 'intelligent'.
If you can get hold of one, it would be fairly simple to test. The pin numbers are marked on the wiring diagram.

 

Mine became silent and using the key in the drivers door to lock and lock it once restored the chirp