Have a 1995 vdp that sat in a warehouse for 6 years and narrowing down the issues. (Wish I could have afforded the 35k for the xke convertible v12 that was parked in the same warehouse).Fixed the bad shocks, bad bushings, flat spots on the tires, 7yr old fuel issues, now working on the keyfobs/security module. Could not get any chirps from entering programming mode. Car would not auto lock/unlock all from the door lock. Replaced the security module beside the gas neck at the trunk and could control all locks from door lock, would lock all when put in drive and would unlock all when put in park. Tried to program fobs and got chirp for programing mode but would not get signal from fob to the scm when pressing large button. Would time out and chirp again after 15 seconds. Thought it might be the antenna on the back glass but have realized, the replacement scm module I replaced with was from a 1997. The one I had was a lna2600bb/xxx and I replaced it with a lna2600cc/xxx. For anyone in a simular situation, the lna2600bb scm looks for a key fob that transmits at 315 mhz and the lna2600cc looks for key fobs at 433mhz. That's why everything works between the bb units and the cc units except for programing the key fobs. There is also a lna2600bc unit at 315mhz. My luck. I have found 2 working cc units but no bb or bc units. Belive they made the bb and bc 315mhz units from 1995 to mid 1996 and switched to the cc units in late 1996 to 1997. If you find any lna2600 scm modules, they will all work from 1995 to 1997 on locking and unlocking the car and also putting the car in security mode. To program the key fobs, you will need to replace with the correct frequency for your fobs. Either 315 mhz or 433 mhz.
will bide my time waiting for a bb or bc unit at my local junkyard and proceed to fixing my airbag dash lights and ac system. At least I'm down to 3 problems with a car that now rides like a dream.

 

I have a similar issue with my 1997 XJR. I let the battery run down to about 5V over the winter. With the battery replaced, the security/central locking system still does not function. My car has the LNA2600CC. I've had trouble finding a replacement. As luck would have it, one became available on ebay today and I ordered it.

Currently, there are three LNA2600BB's listed on ebay.