My 1986 Daimler Double Six would start but ran badly and died on new years day. I’ve tried starting it a couple of times since that morning with the same results; starts but runs poorly, emits white smoke at first, and eventually dies and won’t re-start. The last time I had that problem and went through all the usual suspected components, it turned out to be the computer and I had to buy one from a breaker yard in England. I later saw one for a similar year XJ12 on ebay and bought it for much less, so I do have a spare to try. I hope swapping the computer gets it back to normal since it was doing so well before this. An odd thing is that the Code Alarm remote fobs were no longer locking and unlocking the door locks even with new batteries in them, but the driver door lock switch did, and now the driver door lock switch is not locking and unlocking the other doors. Can anyone tell me if the door lock function is controlled by the main computer? (Open the pod bay doors, Hal. I’m sorry, Dave, I’m afraid I can’t do that).
I may have to take the back seat out to see if the aftermarket Code Alarm control’s brain is hidden there and try to figure out how to disable it. The alarm was originally installed by the first owner in Belgium and I’ve never had an owner’s manual for it to know for sure what the two micro-switches behind the left side of the dash are supposed to do, but the remote fobs have previously worked to silence the alarm’s beeping when the battery is re-connected by locking and unlocking the doors. I removed the alarm siren years ago but left the beeper, and there are also two LED lights on the steering trim with a red one that blinks when the alarm beeper beeps.