i have an xj6 , 1995 , has been stood for several months and the battery has gone flat , put a new battery on today but from the fact that the engine check light goes out i have found out the immobiliser is active . have re-registered key with valet switch procedure but it is still not disarming , any ideas or is it a job for someone with odb ?

 

or even obd . he he , have tried swapping security units with one of my other jags today , this one after much messing about , still wouldnt go with another unit from a running car , or is it not that simple ..help please..

 

You have a UK spec car. There is a transponder chip in the ignition key that is matched to the Security & Locking Control Module (SLCM). When the ignition key is inserted into the ignition switch the security chip in the key is read and compared with the information in the SLCM. If they don't match the car is immobilised. Unfortunatley dealer level tools are required to match the module to the key. If the module is replaced on it's own the ignition key security checks will fail and the car will be immobilised. The remote key fob simply enables and disables the alarm on UK cars and does not reset the immobiliser.

 

Thanks for that information .
I have now tried changing the chips in the key heads also, so that the chip matches the security module, but the same symptoms ,ie- engine check light goes out .no sound from fuel pump etc and no cranking, i am now thinking about wiring a switched supply to the essential systems as a temp measure as the car is supposed to be one of our wedding cars next weekend . if that works then after the wedding , i will have to get the module re coded i guess .

 

having just sent my xj300 to have the key/security unit recoded it has come back with the same symptoms , ie the engine check light still goes out after a few seconds of turning ign on and there is no sign of the engine turning over or sounds of the fuel pump priming as there always was . have i been ripped of with the supposed recoding , or is there some other possible reason that the engine check light would go out ....help please , this car is supposed to be one of our wedding cars in a weeks time . thanks in advance guys