I have a 1990 Honda Civic EX and it only has 120,000 miles on it. We replaced the alternator and the battery and it ran fine until last month. Now, 50% of the time when we start the car, the battery light is on and the alternator won't charge the battery. When the car dies and we jump start it with another vehicle using jumper cables, the light goes off and everything works fine. If we put a trickle charger on the battery to charge it, the battery light still comes on and the alternator won't charge the battery. It seems like a short somewhere in the electrical system? or someone else suggested a bad relay? Has anybody else had this problem and is there a simple solution? The car runs great except for this new problem.

 

Most likely you got a dud alternator from a chain store.