I am looking to buy a used rear windshield for my 98 XJR. I don't need it, but they will become (already are??) impossible to find, so having one on hand would be ok with me, since I have no plans to ever sell the car. I have a place to store it. Anyway, I need to know two things:

1. How do I tell if my car requires the 433 mhz or 315 mhz built in antenna? I don't see anything on the VCATS label, and I'm not sure where else to check.
2. Is there a way to verify the mhz of an antenna, in the event that I find one? Seller statements are ok, but I'm sort of a 'trust but verify' kind of person.

Thank you!

 

Hey there aquifer, to my knowledge these cars were not factory equipped with antennae in the rear glass.
There used to be some eBay sellers that had conversion kits, however a stock equipped x308 will have it mounted in the rear right fender,

 

It's the security antenna, not the radio antenna. There are actually two different part numbers for the rear glass, depending on which security antenna you have. I think this antenna is for the key fob remote. Sorry, I should have been more clear what I was asking about.

 

The SLCM will have the frequency?

 

Vauxi, I should have known that! Especially when I reread the post and recognized the frequencies.

 

Just measure the length of your antenna and make sure to match - the higher frequency will have a shorter wavelength/shorter antenna. Not sure anyone selling a used screen will know the frequency of the antenna unless it's marked, but they can measure the length.

 

Jaguar issued a TSB for the X300 along the same lines.

 

A picture's worth a thousand words. I owe you a debt of gratitude. I've never been able to get the key fob to program on my Mark 2 XJR project. Plums (Bob) had the great idea to paint the antenna on the Mark 2 rear windscreen with defroster repair paint (I miss that clown). I copied the antenna profile on my wife's car which (I now discover) has the wrong 315 Mz frequency. I'll calculate the antenna length for the higher 433 MHz antenna and duplicate the later profile. I do notice the key fob Jag sold me for the 2001 donor car has an ID ending in 322 - not the 315 on my wife's fobs - and not the 433 I'd expect to see. Not sure what that's about but we'll make the change and see what happens. Many thanks for the post.

 

Great advice, thanks everyone. Here is what I have learned: not sure why I didn’t think of it first, but I googled the part number on my fobs. They are 315mhz. Going by Motorcarman’s pdf, this is confirmed based on the drawing of the antenna in my rear windshield. I definitely have the 315 antenna. All of this info will help make sure I get the glass with the right antenna. I did see in the pdf that the antenna isn’t supposed to make too much difference, as long as the fob and the SCLM are the same. However, given a choice, I might as well have the right antenna too, in my opinion.

When I first got the car, it had only one key and one remote fob. I got a new fob, a new key, and a valet key from Jaguar at the time, and paid them to program everything so it worked. All keys and fobs worked fine, and they still do. I use the old fob and old key as spares, because the new ones look nicer.

Again, thanks everyone for the helpful advice!

 

It never really occurred to me where the receiver was for the key fob signal. Looking into it, that placement makes perfect sense. It does however, not make sense that Jaguar would switch frequencies. I wonder what caused them to do so?

 

There are different frequencies for different countries.
Sometimes it's a matter of GOV'T REGULATION.

 

american cars with the 4-button ford remote are 315, european is 433. earlier NA cars with the special 4-button remote i don’t know but probably 315 as well

doesn’t really matter either way

 

So it goes without saying that with this type of system, there is a constant (if minor) electrical draw on the battery.

 

Total quiescent drain should be around 30ma. The SLCM does add to the total.

 

That is not much. It’s good to know though.