I have a 1999 Miata with 71k miles on it. It is garaged and never taken out in bad weather. I also rarely, if ever, drive it at night. Tonight was an exception and I noticed that the headlights seemed pretty dim. I have had the car since 2004 and don't recall ever changing the headlamps. Can just the age of the lamps cause the dim display? Maybe I am just used to the brighter lamps in my Hyundai. Would changing the lamps help? If so, what is a good brighter choice?

 

Usually dim lights can be attributed to a voltage drop. I suggest you check all the associated earths making sure there clean and tight. A competent mechanic/sparky can quickly find them with a multi-meter.

 

The first thing no matter the age of the battery is to have it load tested. Then check the 4 connections at the battery and at the ground and starter.

If you want upgraded headlight bulbs contact the http I provided below .

https://www.headlightrevolution.com

 

Thanks. I am replacing the old bulbs. They were a bear to get out because the squeeze tabs had not been touched in over 20 years. I will check to see if the new bulbs are brighter than the old ones. Thanks for your help. G

 

Thanks The battery is pretty new, but will get it all checked out.. Alternator is fairly new too, maybe a year old. G

 

Fairly new and a year means nothing when it comes to actually first checking them to rule them out of either the problem or part of the problem..

The simple question when you purchased the battery before you left the store or before it was installed did you have it load tested or did you assume new battery must be ok. Most do not even know how old there battery actually is when they buy it new. The date code is not the date sticker and is actually a long code on the top case generally the lip.
You would need to get that number go to the manufacturer website and use their date decoder to find the actual birth of the battery.
It’s easier to just get the battery load tested. Call it preventative servicing even if the battery checks out good . If not then you at least can prevent possible future electrical problems by replacing the battery now if it failed the test.

 

I would think your Miata has H4 bulbs which do not degrade over time like the other incandescent bulbs which go black as the filament burns away over time. I still think your problem is a (voltage drop) bad earth in that part of the light circuit. Do you have a multimeter?