Hi guys,

I'm new here, as a member that is. 32yo, riding my Jag daily since 2019, quite a lot of work but with help from the threads in this site a lot is fixed.

One thing that's not working is the key fob and with the numerous threads there are, I can't seem to find the solutions for it.
During winter when I was out for a while the car wouldn't respond to the key fob anymore, I thought it was the cold + old battery because the next day all worked fine again. Kept getting worse, so I replaced the battery for the exact same that was in there and had worked for the last 7 years (1x C2032), closed the case: all good. Next day won't work.
Read some more, cleaned the circuit board, closed the fob: again, all worked very well. Next day it won't work again.
Than I saw advice to place a aluminium foil between the battery and the circuit board, because the contact might be weak. Not sure if that's a "solution", so I lifted the pins underneath the battery, maybe that would help and indeed, when I closed the fob and tested it, it all works great. But I think you can guess by now what happened the next day: Nothing at all.

It seems to me that everytime I remove the battery, it sort of resets, works, and than falls back into the old issue.
If the fob works, every button works. If it doesn't, non of the buttons work... No matter how many times I press a button.

What's strange in my eyes is that it sometimes actually does work, so I don't think it should be "paired" with the car again, or is this my mistake?
What I want to do is check the Security Locking Module in the trunk for corrossion or any loose connections.

If you have any tips on where to look for, much appreciated!

I have the newer type, with buttons on the circuit board.

 

O I have to add:
Sometimes when it doesn't work in the morning (and have to open the car with the key) it also won't lock when I arrive at destination but strangely enough it does lock when back home end of the day.

 

As out ladies age, the lock mechanisms seem to become problematic. Some
members have found that the varied locking mechanisms work much better
after removing the door card and lubricating the varied joints.

 

(un)Locking with the key always works, it's just the fob that seems to have a mind of it's own.
Does that rule out the mechanism?

 

Some have found that the internals of the key fob sometimes get a bit
"gunked" up, causing the buttons to not engage as well as they should.
If the fob works "sometimes" and not other, it is difficult to determine
where the problem is. I would first replace the battery and clean up the
internals in the fob, and see if there is a good result.

 

I replaced the battery for the exact same that was in there and had worked for the last 7 years (1x C2032), closed the case: all good. Next day won't work.
Read some more, cleaned the circuit board, closed the fob: again, all worked very well. Next day it won't work again.

 

Test the battery (after it does not work) to see if it maintained a charge.
If not, the fob has a short and is draining the battery. If it still has a charge
then you can surmise the problem is with the receiver.

 

When it doesn't work, I open the fob, close it again and it works (for a day). Same battery.
Think that proves the battery still has charge?

Receiver = SLM in the trunk or antenna on rear window?
Check for corrosion and loose connections? Or would you suggest anything else?

 

It could be that opening the fob case resets the fob electronics in some manner
that allows it to send the fob signal. This is not a common issue.

 

Yes, seems like it, but why does it get... corrupted again after using..?
Can it be the fob then, or do you still think the receiver?

 

I think the handbook says 2x2016 not 1x2032. People say it's the same thing but I know my fob responds faster and from further away to a button press with 2x2016 than the other way. That's both as new fresh batteries too.
You are wiping the contacts & back of the buttons to get rid of the oily mess that oozes out of the old plastic? I think you mentioned it, but just double checking.

I think I'd be tempted to look for another fob on ebay etc, just make sure it's the same wavelength. Then pair the both to the car (you have to do all the fobs at once) and see if the new fob always works or not.

 

The early cars, around 97 and 98, used a fob with 2 x 2016 batteries.
This gives about 6V for what I assume is 5V logic chips used in the fob.

Later cars, say 99 ish and on, use a Ford style fob with 1 x 2032 battery.
This uses 3V for 3V logic
Using 2 x 2016 in later fobs, may work as it might overcomes voltage loss due to worn contacts etc however you also risk
damaging the fob as it is only designed for 3V

So 2 x 2016 is not the same as 1 x 2032 even though it may physically fit.

 

Before digging any deeper go get new battery of reputable brand and from reputable source, yours showing typical symptoms of dead one.

 

I don't think you wrote it in the thread, but your Jag is a X308 from 1999. I am pretty sure that the battery for the remote is CR2032 (and not 2 x 2016). I have a feeling that 6V could damage your remote.
Do you have a multimeter?
Did you measure the voltage of the new (and old) battery?
Those CR2032 are cheap as chips, but they could also have been old on the shelf and not have their full voltage anymore. Just yesterday I replaced a similar 3V battery in the remote of my cooling vent in the house - the old battery still had just above 3V, but it worked only very short distance, the new battery has nearly 3.5V, and the remote works now a dream.

I agree that your symptoms are strange, but lacking any other ideas, I suggest to property clean the contacts, which touch the battery and make sure that those contacts have no sign of being worn out mechanically (stress ageing). One way to rejuvenate the contacts on the bottom is to apply a tiny bit of tin after cleaning them (via soldering iron).

And just for good measure try another new battery an measure it, if it is quite a bit above 3V.

You never mentioned, what happens, if you use the remote of your second key!?
Does that mean, that you have only 1 key? That is highly dangerous and could cost you lots of money, if you loose that.
If you have only 1 key, have at lease one more done.
The remote may need to be programmed by a specialized locksmith for a lot of money, the transponder would be cloned one (if you currently have only 1 key).

And then you can see, if the car opens with the new key-remote.
I have 4 keys for all my Jags. The 2 OE keys never leave the house - for good reason.

So you have the 1999 X308. Which remote is it? I know the 1998 had a separate remote to the key, the 2003 had the combined Flip key.
I also know (because I did that): The 1998 remote cannot be programmed by yourself - which is silly, and the old remote cannot be bought anymore.
My cunning solution - which you could do as well: I bought the door lock security unit (a little black box) from a 2003 X308, put that into my 1998, got rid of the old remote (someone on ebay was very happy to buy it (that was, when it was still possible of offer something for sale on ebay - I do not accept that ebay demands now a copy of my ID card, before I am allowed to sell anything - risk of ID theft!)).
Then I bought 4 new Ford Flip keys (cheap online) had them cut (via mail order - I have send them the removed 4 blank blades - as the local locksmith is way too greedy) and programmed transponder and remotes myself - without special equipment.

 

^
The correct batteries (at least for later North American cars) is definitely two CR 2016’s and NOT a single CR 2032:

 

OK, if that is the old (separate from key) remote, than I know nothing about it - it could well be 2 x 2016) - the only thing I know about that one is, that it is close to impossible to buy one of those...
My assumption that it cannot be 2 x 2016 was based on my assumption that the 1999 has already the Ford Flip key.

But it just dawned to me: I too, have the 1999, not the 1998 - and yes: That is the old separate remote. No idea. how many batteries.
Still leaves you with the problem, which I was writing about in detail above: If you have only 1 key, you are utterly buggered once you loose that one.
And swapping the security module - as described above - for that of a newer model might be an idea.
Just an additional note about that: Normal flip keys are 6-digit-coded tibbe keys - the X308 is a 8 digit coded tibbe key: I managed to get that longer blade from a non-flip key into the flip key!

Other than that: If you have one 1 key and don't want to do anything about it, just do at least the very bare minimum:
Find instructions on the net - e.g. as below, but I am sure that there are better guides, and note down the code of your key somewhere, so that it can at least be cut, if you loose you only key:

https://www.americankeysupply.com/pa...-the-tibbe-key

 

Damn, i was dropping 2032 into fob since always, just swapped 3020 for 2016 and now it locks from 20m at least v 5m with 2030
This fob gives up on just below 3v, partially discharged 3v+ battery may be ok on warm day but drops to 3v- at subzero thus fob stops, warm up fob and it will go for a while but drop out at next cooling event, it gives really narrow margin of use and almost full battery may cause problems on cold days, it won't happen with 2x2016 which will drop to 1.5v per cell before fob gives up

 

That's what my handbook says for a 2000 UK car too, with the later frequency fob. As far as I'm aware the only change from the early to late x308s fob wise is the frequency. Hence I use 2x2016 & it solved the issue for me.

 

Last Version of the Handbook switched up to 2032. This is for the 2001, but no changes (that I am aware) since.

 

The photo above was from the handbook for a 2001 XJR so I’m not sure when that switch might have been made.