Today's mystery - 300 TDi ignition key

1996 300 TDi CSW.

Well today I finally got myself organised and had a second door and ignition key cut using a local key cutting service - when I bought the vehicle it only came with one set plus one alarm/immobiliser PLIP unit. No issues with the keys doing their job but when the engine has started with the new ignition key, a flashing red light comes on which is positioned on the warning light panel. To cancel the light I have to use the "Unlock" button on the PLIP and all is well - this is with the engine running. There is no problem with starting and stopping the engine with the new key.

I did glance at a previous thread a few months ago about a key issue and I'm struggling to recall if it was a similar situation to mine - but now can't find it. The original ignition key does have a black plastic cover over part of it and I'm wondering if there is some sort of transponder or similar impregnated in to the plastic - if you looked at it you would say no it hasn't but who knows. It would also be of assistance if someone could explain what the flashing light is warning me about.

Any ideas would be appreciated.

I think the transponder may be in the remote. Try disabling the alarm and then put the remote at a distance from the car. Try the key again and I think you will find that it wont start and the light will flash.

Found the answer - when I tried out the new keys I didn't have the second PLIP with me. It would appear that if the PLIP is attached to the key ring (that is, it is in close proximity to the following), the box under the dash which controls the alarm/immobiliser detects the PLIP and the flashing light does not occur.

As I thought but now confirmed by my Land Rover dealer, the key itself does not have a transponder built in to it.

That's what I tried to say above!