Questions and Answers

Mazda Miata Flickering Lights
Q. The problem is that my lights high and low beam flicker in my 1994 Mazda MX-5 Miata. I took it in to Pep Boys and they tested the electrical system they said everything is okay.

I bought an amp meter, the kind you stick in the cigarette socket, and it always stays 15.1 volts to 15.5 volts. Could you please e-mail back with a hint as to what could be bad. I wanted to just go ahead and replace the alternator but the people at Pep Boys said that it did not appear to be bad. I have not had any other problems with this car. Help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Thanks,
Art
Fort Worth, Texas

A. 15.1 to 15.5 volts is considered overcharging on this vehicle. The regulated voltage is supposed to be 14.3 to 14.9 volts at idle. You didn't say anything about the battery however. Did anyone bother to check it? You can't accurately test a charging system with a weak or bad battery.

Most often the kind of flickering you describe is caused by a weak or bad battery. It is not storing enough power to smooth out the normal voltage fluctuations of the alternator. It might also explain the higher charging voltage as well. If your battery is more than four years old, I would simply replace it and then see where we are.

I would recommend that you have your Mazda dealer to a complete charging system check, including load testing the battery and the alternator.