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View Full Version : Cheap and Easy LED 3rd Brake Light Conversion! -=NB=-



dweikum
03-14-2018, 09:19 AM
Miata NB - 3rd Brake Light LED Conversion

After installing a Brake Light Flasher Module on my 3BL in order to gain extra visibility, I was underwhelmed with the performance of the unit using the stock bulb. I went with a module from 3rdbrakeflasher.com that had a Brake Force Monitor and was programmable for the number and speed of flashes under different situations. More options is better. So, the unit works great, I got it all programmed, but the stock single filament bulb in the 3BL was not up to the task…oh, it flashed, sort of...more like ramped up and down as fast as it was able, but just could not keep up with the new electronics. It only attained full brightness when the flashing sequence ceased. Not what I was hoping for.

BTW, yes, I have read the discussions on if the flasher is the *right thing to do* because it may be *annoying* to the drivers following behind or it's *not standard* and they will *have to think* about it...all things considered, I opted for more visibility and my and my family's safety over someone else being annoyed. They already won't like the way I drive it like I stole it, so 5k-'em. Maybe if they are really annoyed then they will get off their damn phones and pay attention to the task at hand.

Getting back on track, while doing my online research on LED replacement 3BL, I stumbled across this post (http://mazdaroadster.net/showthread.php?7226-Cheap-and-Easy-LED-3rd-Brake-Light-Conversion!-(NA-and-maybe-NB-)) on mazdaroadster.net (thanks @jnshk!) where the OP retrofitted the 3BL on his NA with an LED light bar by modding the stock housing. This looked promising (and cost effective) so I ordered the light bars to give it a go on the NB. Of course, it was not anything like the NA, so I figured I would document my variation to add to the mix of DIY info for those who follow.

I used the United Pacific LED Taillight Bars 39687B from Summit Racing…low price, good quality, fast shipping. In the end, it worked like a champ and now I am SUPER annoying!

https://photos.smugmug.com/Miata-Projects/i-sDjrMDp/0/d1defb69/L/3rdBL-Finished-L.jpg

Here’s the rundown with supporting photos:

1. Remove the stock 3BL from your NB.

- Unplug the connector to the stock bulb housing
- Remove the 2 little wire guide grippers from the studs.

https://photos.smugmug.com/Miata-Projects/i-fkS5763/1/7e1c1aaa/S/3rdBL-15-S.jpg

They have opposing claws that grab the threads on the studs so just pry them open with a dental tool or similar and pull them off.

https://photos.smugmug.com/Miata-Projects/i-K5tcxJQ/0/0c3744d6/S/3rdBL-13-S.jpg

- Remove the 2 nuts that hold the housing in place. These are 10mm and require a deep socket.

https://photos.smugmug.com/Miata-Projects/i-QnmznF5/1/da5d4f54/S/3rdBL-16-S.jpg

- Slide a flat blade screwdriver into the slot on the passenger side and press the tab into the center to release the side clip. The housing should come off now. Be aware that the foam seal between the housing and deck lid will most likely disintegrate and need to be replaced.

2. Disassemble the housing.

- The housing appears to be 2 pieces clipped together.

https://photos.smugmug.com/Miata-Projects/i-CBfJqFR/0/6e58085b/S/3rdBL-2-S.jpg
https://photos.smugmug.com/Miata-Projects/i-3Rk8rbh/0/828613e6/S/3rdBL-1-S.jpg

Release the 2 clips and open the housing like a clam shell.

https://photos.smugmug.com/Miata-Projects/i-nM9Lv9n/0/ab05206e/S/3rdBL-3-S.jpg

Disconnect the 2 pieces at the web, we will reattach when finished.

https://photos.smugmug.com/Miata-Projects/i-Z3gx2fD/0/f2f596b9/S/3rdBL-4-S.jpg

- Next the clear lens needs to be removed. There are 2 tabs holding one side and the other side is held in with some gray adhesive that is heat sensitive.

https://photos.smugmug.com/Miata-Projects/i-8jLpLmk/0/371fc046/S/3rdBL-5-S.jpg

Bring out the heat gun and warm it up. I used a dental tool to help free the goo.

https://photos.smugmug.com/Miata-Projects/i-GCWTpgp/0/bec73ee8/S/3rdBL-7-S.jpg

Release the 2 clips with a screwdriver and start pulling the lens from the housing.

https://photos.smugmug.com/Miata-Projects/i-xsSKsxd/0/7882ec22/S/3rdBL-6-S.jpg

Be aware that the goo is now hot to the touch. Don’t worry about the residual goo in the holes, the lens is not going back in.

https://photos.smugmug.com/Miata-Projects/i-DzzXZMZ/0/a77c6a4f/S/3rdBL-8-S.jpg

3. Install the light bars in the housing.

- I went with 2 light strips, I’m sure one strip would be great, it would be 3 times as bright as the original and be clean and subtle, but I wanted maximum visibility and since there is room for 2, I went with 2. I sanded one side of each strip down a bit so they fit together better. They came with an uneven surface on the housings due to manufacturing. Zip-tied together they are easy to install in the housing.

https://photos.smugmug.com/Miata-Projects/i-rn88sLm/0/a5dcfd62/S/3rdBL-9-S.jpg

- With the housing sitting on the table face down, the LED bars can sit face down and be secured to the housing.

https://photos.smugmug.com/Miata-Projects/i-crxF42Q/0/8b479ef4/S/3rdBL-10-S.jpg

I used JB Weld 2-part adhesive to permanently secure the strips into the housing. You could use silicone or something else if you want to be able to remove them one day, but JB Weld sets in 5 minutes and cures in an hour and it will never come apart. I wanted to finish this job quickly and did not want to smell silicone for days.

https://photos.smugmug.com/Miata-Projects/i-gJZsqQT/0/8bfd44f3/S/3rdBL-11-S.jpg

- Use a spring clip or clamp or put it in a PanaVice to hold it while it cures.

4. Reattach the back of the housing.

- Press the back onto the housing so the 2 clips catch, and the web meets the housing.
- Mix up a little more JB Weld and apply to both surfaces of the web and add to the outside of the connection to add a little strength.

https://photos.smugmug.com/Miata-Projects/i-jzrTnj9/0/f81aaf15/S/3rdBL-12-S.jpg

- Allow to cure based on adhesive used.

5. Reinstall the housing (and probably a new seal) into the deck lid.

6. Wire up the lights.

- Red wire is the high output lead (brake lights.)
- Black wire is the low output lead (running lights)
- White wire is the neutral.
- Connect up the red to the brake light input wire (hot when the pedal is depressed)
- Connect the white to the neutral wire (the other wire at the old fixture)
- Reattach the little gripper wire guides to the studs (not going have a death grip anymore.)
- Tidy up the rest of the wires. Zip ties are your friends.

7. All done now! (https://photos.smugmug.com/Miata-Projects/i-NBS2Pth/0/02a573bf/960/20180312_151644-960.mp4)


Tools Req'd:

- Slotted Screwdriver
- Small slotted screwdriver or dental tool
- 10mm Deep Socket and ratchet
- Small/Medium spring clamp

Parts List:

- LED Light Bar - summitracing.com/parts/UPD-39687B
- 3rd Brake Light Seal - https://www.prioritymazdaparts.com/oem-parts/mazda-high-mount-lamp-gasket-nc1051592a
- JB Weld, Plastic Weld - amazon.com/J-B-Weld-50132-PlasticWeld-Quick-Setting/dp/B009EU5ZMK
- Flasher Module - 3rdbrakeflasher.com/brake-light-flasher-c-65/stop-alert-flasher-with-gforce-sensor-p-183.html

HarryB
03-14-2018, 10:12 AM
Wow, that's BRIGHT

Phatmiata
03-14-2018, 10:18 AM
Awesome write up!! Thank you sir !!

atank
03-14-2018, 07:59 PM
Very good write up!!!!!!!!

Agent☣Orange
03-21-2018, 10:10 AM
I love electronics writup like this. Well done!