Land Rover Repair: 96 lr disco diff wont lock, fly wheel, abs light

Question
Hi Bruno,
Here is my problem: I own A 96 disco. I am the 4th owner,I personally known the last two, this car has been fanatically mantained. all fluids are synthetic, all belts and hose are new.It has 136k miles.automatic.
The diff wont lock. The shifter is not stuck it goes to the  hi & low positon, and lock and unlock position just fine, but the dash light does not illumunate,nor does the streering get stiff when trying to turn on solid ground.
hi and low gear wroks fine. all linckeage is there and funcional. I removed the center console but did not remove the rubber boot around the shifter because I could see from below that it was not a stuck shifter.
here are some things I know are wrong with the car, maybe they have something to do with the diff problem.
1st: the abs light is ,and has almost allways been ON.I think this is a regular problem.
2nd:the transmision seems to make a grinding noise only some times when you firts turn the car on, but not in all gears, only park and neutral I think. I suspect that it might be my ignition swicth getting stuck and leaving the starter engaged againts the fly wheel, because the noise gaoes away  if I re-start the car  
the car runs great other wise  

Answer
Hello JP,
Series one discos also rely on the transfer box solenoid to shift in diff lock so if the problem  is not within the shifter assembly, then it might be the tranfer box solenoid or it's circuit that has failed. The solenoid is located on the top right of the transfer box. If that is not the cause, then the internals have failed.
As for the abs, it's very hard to determine the cause of the problem since I can't scanned the ecu for fault codes.  Yes you are probably right as for that grinding sound heard when you start the vehicle, as discos are known for bad ignition switches.
Sorry I can't help you more
Bruno