Land Rover Repair: Electrical/air suspention problem

Question
P38 2001 4ltr  My battery started draining very quickly and at the same time one of the relays in the engine compartment fuse box was getting very hot. On closer inspection the fuse box was melting just beside that relay.Purchased two second hand fuse boxes to find they had the same melted points beside  the same relay point. So I thought not much point in fitting those and bought a new one. I should say the relay was the one for the air suspension.Once fitted I checked the alternator to find it was only putting out 10.5 amps.when the a/s relay was removed it went up to 13.1 amps.Tried new alternator-same thing. Going by the other fuse boxes it seems like a common problem, but what is my problem? many thanks

Answer
Fuse box meltdown is very common

You should unplug the suspension compressor and see if the hot relay resolves.  If so, you may have a bad compressor.

If the alternator output reading you cite is accurate, the alternator is bad or there is a wiring problem.  

To test the alternator put a clamp on probe on the heavy output wire from the rear of the alternator and put on lights, high fan, defogger, etc.  Rev engine and see what output you show.  Also check voltage.  Alternator should hold over 14v at near rated output, which is 80+ amps depending on year