XJS alarm remote

I wonder if anyone can help. I’ve got a ’93 4.0 XJS (VIN xxxx189559) that has always had 2 (non-transponder) keys but only a single remote; something I’ve finally decided to try to address since I don’t like having a single point of failure. This existing remote seems to be after-market since it has no Jaguar branding and the PCB is stamped as being ‘Tech Tronics’ but I wonder if it is simply a replacement fob for the OEM system since the alarm seems to respond with the expected ‘chirps’ and ‘warbles’ that I have seen mentioned online.

With that in mind, if the alarm is OEM, can anyone advise where it would be normally located? Also if it is OEM, is there a simple way of determining whether it would operate at 318mhz, 418mhz or & 433mhz and which of the long list of fobs I might need? At the moment I’m rather lost in a list of DBC100852,
DBC10086, DAC6160, DAC7970, DBC10085, DAC7990, DBC100842.

Again, assuming the alarm is OEM, I’ve seen a couple of processes mentioned to code the replacement/additional fob to the car – one involving a ‘valet switch’ (Is DBC12022 correct?) that my car does not have. Again, is there a way to identify which method will be needed since I have also read that the ’03 XJS might not have the wiring for the valet switch under the centre console lining.

Thank in advance :blush: :blush:


Personal advice - throw that sht away, real men don’t use this type of toys…
Your alarm box will be trackable via wiring - 99.9% of these are connected to the inertia switch - just remove the the cover above footwell and trace those wires.
Your transponder rather looks like central locking remote, it has no code as the label suggest and can be remade by teenage ninja turtle with soldering iron. Try universal garage door remote (programmable).

The Facelift XJS cars were all pre-wired for an alarm system with the Alarm Module to be located in the boot behind the trim at the right rear - between the antenna motor and the right rear tail light. Sometime about mid 1993, the '93 XJS was changed from the older Alarm system (with the backup Gel Cell battery) to the newer system without the backup battery. There is a Jaguar harness that enables the '92 and early '93 XJS’s to use the older system, or the newer system without that harness.

The newer systems (XJS included) require the receiver in the car to recognize the remotes - the remotes are not programable. That’s why the procedure requires the pigtail that is in the area of the center console to be part of programing the receiver to recognize several remotes. Applies to the newer system from mid '93 through '96 XJS’s. See pics of the Alarm system connectors in the '92 XJS.

Early Alarm System (3)
Early Alarm System (4)
Early Alarm System (5)