I have a 1999 disco 2 diesel. Car starts and runs fine with key with electronic components of the remote door opener. Other key does not have good electronic. Bad key opens door and powers up all dash functions including fuel pump but will not crank engine. Everything I have read says the basic key should start everything if the car was unlocked with the remote control. Both keys lock and unlock doors using the drivers door lock and manually unlocking door with key. Both keys power up everything but the bad key missing electronics will not crank starter. The one interesting thing is that when the drivers door is opened after unlocking the doors with the key the alarm sounds and can only be reset with the good key in the ignition. Anyone know what's going on. Car is in Costa Rica.

 

Perhaps unlike the North American trucks yours may have a coil around the ignition that picks up the electronic parts inside the special key. See attached page from RAVE shop manual. Solution would be another expensive key, plus getting truck and key to accept each other, not 100% sure if you would need dealer / advanced shop programming on that.

One way to test for this is use the plain key in the ignition, and just hold other key close by to be "scanned".

Real problem if you left the good key back in the show-me state.