Land Rover Repair: speed control, t4 system, dry rot

Question
i bought a discovery 4000cc the year is a 2000 and the speed control douse not work.the switch light comes on but that is all.Can you please advise.

Answer
90% of cruise problems stem from dry rot cracking of the vacuum hoses, especially the hose to the dump switch above the brake pedal.  Check that.  If you don't get anywhere you will need a shop with a T4 system.  That's the only tester that can talk to the cruise and test it.