Hello, I just picked up a nice low mileage 1996 XJS 4.0. I've been driving it the last few weeks with no issues. Yesterday I went to take the car out and the key fobs were not working. I unlocked the car manually and turned the key and there was no cranking. The battery has a full charge and the batteries in the key fobs are good. I checked all of the fuses and the inertia cut off switch. I think the problem is somewhere in the security system....I don't have the security system manual. Any suggestions ? Thanks.

 

Sounds like the security system. Put the key in the ignition switch and rapidly turn the switch to accessory and off three times, that may/should turn the security system off. I've had similar problems with mine recently. IMO as these security systems age they are becoming troublesome. My '95 is going to be laid up soon for a variety of service and repairs and I will be researching these security systems. Stay tuned...

 

Thanks Roger95, I tried the key sequence, no change. I unplugged all three terminals from the security module and everything is the same, no change. I'll bet that the module is bad. I think I'll start researching security systems also....or I'd like to remove the system completely.

 

PawlB,

If you're sure the fob battery is ok, try re-pairing the fobs back to the security module. We gave seen occasions where the modules just forget their pairings. It's worth a try for the few minutes of effort.

Good luck

Paul

 

I ordered the security manual from Ebay and I'll try to re-program the fobs when I have a little more knowledge of the procedure. I've been doing a lot of reading and there seems to be a lot of different ways to reset the security system. The fact that I don't even get a "chirp" when I re-connect the battery puzzles me, unless the whole module is bad.

 

So I got word from a Jaguar tech experienced with the XJS. Apparently disconnecting the battery for a few minutes or even three hours is not enough time to reset the security module. He told me to disconnect the battery for 24-48 hours. As soon as I reconnected the battery the alarm sounded. I disarmed it with the remote, locked the boot with the key, opened the drivers door with the key, toggled the ignition switch 3 times between off and accessory and the car started. This doesn't make sense to me because I know there isn't a back up battery on the security module (I took it part and looked) but there must be one on the main ECU. Anyway I'm back on the road !

 

Result!

 

I'm not completely out of the woods yet.....now the power door locks don't work !
I'm just going to drive it a while and leave the locks for another day.