Alternator workshop alarm when coolant level is low

Ihave Octavia Mk 1, elegance with automatic transmission. One of the coolant elbow is leaking so my level of coolant drops after every 100 kms drive, earlier I used to get alarm to check coolant level but since few days before getting coolant level low alarm I am getting alternator workshop alarm. I got my alternator output checked its fine above 14.5 v.but once the coolant tank is filled there is no alarm of any sort. Where the fault lies?....