Questions and Answers

Mazda Dash Lights Q. Vincent, I am having sporadic problems with the dashboard warning lights on my 1989 Mazda MX-6 DX (106,000 miles, manual transmission). The "battery charge" and "rear light" dashboard warning lights periodically come on in tandem (never separately). However, all of the external lights are working properly and the battery checks out fine.

Sometimes the warning lights come on full strength, sometimes the lights flicker, and sometimes the brightness is proportionate to the motor's RPMs. The occurrence of the problem doesn't seem to have any correlation to the temperature of the engine.

Other than the described problem, the car runs great. It recently passed it's 100,000 mile check-up at the dealer with flying colors.

I've had bad experiences in the past with mechanics chasing electrical ghosts. Any ideas?

Regards,
Jim

A. What you are describing are classic symptoms of a bad diode pack inside the alternator. The diodes, along with converting AC current to DC current, also control some of the dash lights. It is common for the diodes to go bad and yet the alternator will still charge properly.

You can ignore the lights, but the thing is you won't know for sure if the alternator goes bad. Best thing to do is just replace it.

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