when i have the lights on both driving and headlights, i can actually see them get dim and bright every little while, and it gets worse when the defrost is on high.
the dealer tells me its normal but i dont buy it cause this happens at highway speeds as well as at idle. any ideas tips things to check myself?
TIA

 

The same thing happens to mine, I think they all do it. You will notice dimming when the compressor comes on for the air conditioning system. This also happens on defrost because it uses the compressor.

 

they are very weak alternators. I also think that mazda underdrives them from the factory to help with power output. There are a few companies who can make you a more powerful alternator in the $300 range if you have a big stereo or whatnot.

 

it's normal..if you do have a high powered stereo system though and the power output is not enough then my suggestion would be to use capacitors rather than upgrading the alternator...its a cheaper alternative

 

can you add a capacitor to the existing (cough) kenwood system?

 

capasitors are nice, but only help the stereo, not any of the other problems, lights dimning, ac, so forth.