Wiring It Up: NB2 Headlight Conversion

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The NB generation of the Mazda Miata is as popular with the aftermarket as it’s early pop-up headlighted brother, the NA. You can find lots of visual upgrades like bumpers, fenders, hoods, wings, body kits. Even though there are 2 versions of the NB (the NB1 and the refresh, referred to as the NB2) both versions can pretty much interchange parts with each other. Well, except for one thing.

Headlights.

NB1 Headlights

My old and broken NB1 Headlight.

The NB1 came with a single bulb (H4) setup for both low and high beam. Keep this in mind, it will come up later. If your headlights have remained in good condition, you really won’t run into too many problems, other than maybe having to recondition them if they become cloudy or yellowed from age. If you need replacements however, there is just one vendor to get them: Mazda. The aftermarket for replacement NB1 headlights is practically non-existant at this point. The only vendor who had at one point offered a set, Depo, no longer makes them. Thankfully some can be found from salvage resellers, but it is sometimes less expensive to buy the NB2 headlights than the NB1 set that you need!

NB2 Headlights

The NB2 Headlight. These might be candidates for refinishing!

In 2001, Mazda gave the Miata a visual refresh, some body panels were altered and the headlights and taillights were changed. In the rear, the tail lights lost the orange reflector for the turn signals and in the front, Mazda switched the headlights over to a projector style setup for the low beam (9006) with a separate reflector for the high beam (9005). This headlight style was used for the rest of the NB’s run (2001-2005) and is the headlight most associate with the NB. There are lots of aftermarket replacements available, everything from BMW style halos to full on HID conversions. There are also lots of examples in the salvage reseller market, since they were produced in larger numbers, it is quite easy to find a used factory replacement, far easier than an NB1.

My Problems

Now that the history lesson out of the way, let’s get to the reason I am working on this lengthy write-up! I have an 10th Anniversary NB, a NB1, and my headlights are in sad shape. Originally I was going to try my best and recondition them (I had already purchased the supplies) but upon further inspection, the headlights were going to need more than that. A couple of the mounting tabs were cracked or missing, so repairing them would be a very daunting task. I decided to just replace them and I could not find a set of NB1 headlights. No aftermarket replacements. I eventually did stumble across a set, but once shipping was factored in, it was MORE expensive to buy the used NB1 set than even a brand new set of aftermarket NB2 headlights!

I finally decided to take the plunge and just order a set of NB2 headlights, but it is not so simple as a remove and replace. There is a bit of work that you actually have to do for everything to work properly.

Turning One into Two

As was stated earlier, the NB1 uses a single H4 bulb for low/high beam. The NB2 is a dual bulb setup (9006/9005). This is the hurdle that some people have with this doing this conversion. Wiring can be a daunting task, but for this project it is actually simple. You will need some supplies though:

  • (2) 9006 Low Beam Headlight connectors
  • (2) 9005 High Beam Headlight connectors
  • Soldering iron
  • Heat shrink tubing
  • Power probe/Voltmeter
  • Wire cutters/Wire stripper
  • Notepad
I ordered these from Parts Geek (no sponsorship).

Before you begin, I advise doing one side at a time. This will keep the number of wires you handle to a minimum. Remove the first headlight and unplug the bulb. There will be 3 wires running to the stock connector. You can turn on the headlights and use your probe/voltmeter to figure out which wire is used for the low / high beam. Since I have already done this, I will give you a tip: the wire color for the low (red) and high (white) beam is the same on both sides of the car, the only different wire in the connector is going to be the ground (passenger side:green/driver side:tan and white) wire. Make note of this on your notepad and turn the lights off.

Now would be the time to remove the negative terminal from your car’s battery.

A helpful diagram to make the wiring easier.

This is the part where the trepidation sets in; the wiring part. I have seen this done two ways. First way is to use spade connectors on the new headlight pigtails and then plug everything into the stock H4 socket. That way if the owner decides to switch back to the NB1 headlights, the process is reversible. The second way is to go full send, snip out the old H4 connector and solder in the new connectors. Guess which way I decided to go?

Note both ground wires running to the green ground wire.

Once you have the old connector removed, strip the ends of the wires and prepare your new connectors. To make this easier for you all I have provided a simple diagram that shows how I wired mine. You need to run the grounds for both connectors to the SAME ground (as shown in my diagram). It will be done this way on the driver’s side as well. I have verified that the high beam indicator on my dash is working (some others who have done this conversion have stated their indicator doesn’t) and I have not seen any other issues. Once your connections are done, make sure to use some heat shrink tubing for added protection and connect the battery to check your work.

The Conclusion

Once I figured out the wiring, the rest of the conversion went pretty easy. I decided to solder mine in, I don’t see myself going back to NB1 type headlights anytime soon (I prefer the NB2 style ). There is one more thing you need to keep in mind if you do this: the NB1 bumper is shaped different than the NB2, so using NB2 headlights with an NB1 bumper doesn’t quite fit. You can finesse it to fit or slightly round out the headlight area on the bumper until the headlight sits flush (Dremel made short work of this) or swap to a NB2 front bumper (hmmm..). Other than that, enjoy driving your car with a newer set of headlight housings!

-R