I have a 1984 LR 90 and have developed an electrical problem that I need advice on. The no charge light is illuminated when there is NO ignition. Once the ignition is turned on the light goes out. Normally if the alternator had gone I would expect the opposite. I suspect something in the alternator (diode?!) has gone but I am not sure. Has anyone had this problem? Do I need to change the alternator?