I had two 94 XJS and successfully programmed a total of 5 remotes for them on a Jaguar PDU.
They never lost their programming over the 10 years I had them.
I heard there was an internal battery in the security ECM that could go bad.
Just in case that ECM is faulty, I have one in my spares bin that I know is good.
Have you checked that all the doors (including the fuel door and the boot are closed properly)?
You might have a faulty pressure switch on one of the doors.

 

Thank you for the response. I wouldn’t doubt the alarm backup battery has gone bad. It’s so old. But I believe the backup battery is only to keep the alarm sounding if someone breaks into your car and disconnects the car battery. I don’t think it has an effect on the car recognizing remotes. But maybe?

Everything is closed properly. 🤷🏻‍♂️

 

I had a problem with my 94 when I stuck a temporary 85 door on my 94.
Everything fit fine except the door card and all the electronics worked.
The remote wouldn't lock the door and it took me a while to figure out why.
No door card meant there was no chrome striker plate on the door near the A pillar.
Once I installed a striker plate with some material to thicken it up everything worked fine.
The door wasn't contacting the pressure switch.

 

That’s interesting about the striker plate.

My problem is really I can’t get the car to acknowledge my three remotes (they can’t all have bad batteries), and then after I do program them, the remotes lose their programming after a week. 🤷🏻‍♂️

 

It may be the car battery. If i park mine up for a week or so it will drain the battery. At the moment l have the alarm unplugged as l'm sorting out some wiring there.and the car battery isn't draining . I'm not sure how much the inactive alarm uses, but it will run the battery down.

 

The alarm battery may be the cause of my car battery drain. Maybe I’ll see if one of these battery stores has some kind of replacement. Do you know if the alarm battery is easy to remove? I know where the alarm system is, but I’m not sure where the alarm battery is.

 

On my '93 built in Sep. '92, the battery is located tucked in behind the rear antenna in the right rear fender well. It is hard to see but that is where it is. There is alot of stuff there including a fuse that appears (to me) to not be listed. It's tight but by moving the wires around, you will find the old battery. You may find a replacement by contacting Mal4d. The replacement is much larger than the original but that is all you will find and it does work. Good luck.

 

I have searched around back there and can’t find the backup battery. I do see the alarm box. I can’t even find the alarm antenna or where that fuse might be.

 

At some point, not sure when, the alarm system was changed and the backup battery was deleted. That may be why you can't find one.

 

Have you resolved this Issue?
I have been following this post since you first started it and commented with a few suggestions.
The cars sold between 1992 and 1994 have a mish mash of different components.
I don't believe either of my 1994 coups had back up batteries for the security ECM.
At least I never came across one with my cars, or the many cars I came across during my years in the shop I worked at.
If this is still an issue, you should PM me so we can get together and swap out my spare ECM with yours.

 

Have you read the complete thread ? Most questions are answered there.

 

There is not an alarm antenna in the back. The remote sensor (on my jag) is mounted on the right side behind the trim panel that is behind my passenger door.. I was referring to the radio antenna mounted on my right rear qtr. panel. The battery on mine is stuffed between the radio antenna and the extremely close rear body of the auto.

 

Thank you, everyone, for your comments. I don’t think my car ever came with a backup battery or an antenna for the alarm. The earlier cars must have been different than the ‘94’s.

 

I have read the whole thread. I think my issue is unique to the thread in that I successfully paired my key fobs before, but the car forgot the programming (twice) and stopped recognizing them. And now the car won’t pair to these same two key fobs at all. The car just doesn’t recognize them when it is in learning/pairing mode.
​​​​​​​

 

Thank you for your kind offer. I haven’t resolved the issue. I can easily get my car into pairing/learning mode where it starts chirping. It just won’t recognize any of my three key fobs. So, you think I need a new ECM? Yours is from a ‘94? Or it doesn’t matter the year?

 

It matters a great deal.
What is the DAC number on your ECM?

 

The numbers I have are:
DPP 1050/XX
SCS Frigette

It’s the same numbers as in your photo.

 

In that case, I suggest you try swapping it out for mine.
You will then need to reprogram ALL of your remote fobs.
If it doesn't fix the issue you can send it back.
Only cost will be shipping.
What do you think is a fair price for it?
Steve

 

Steve,
I will send you a PM. I tried sending one the other day, but it doesn’t look like it went through.

 

Update on my issue of not being able to program my remotes to the security system. Steve (equiprx) sent me the extra alarm ECM he had. I installed it, and all three of my remotes synched easily! My system now works!

Thank you so much, Steve!!

Danny