Best DRL solution - looks OEM - easy under-hood connection, converts turn signals to white DRL / amber turn

[centerpunch]

WARNING: I AM NOT RESPONSIBLE IF YOU OR YOUR CAR EXPLODE.
IF YOU DON'T HAVE EXTENSIVE EXPERIENCE WITH AUTOMOTIVE ELECTRICAL SYSTEMS, PLEASE STOP READING NOW.

I'm a believer in DRLs, especially on silver cars that can blend in with the background on overcast days.

I searched here and found several helpful threads, but the ones I found require that you run a wire into the car's interior to make the connection.

However, I discovered there is a source of switched power under the front hood.

The connection is in the underhood fuse box on the passenger side of the car. There are five large fuses. The four to the right are connected to constant power, but the first fuse, on the left, is for the windshield wiper circuit, and is switched on and off with the ignition switch.

If you connect your DRLs to that, they'll come on when the car is on, and go off when the car is off.

I used one wire lug attached to a small fuseholder connected to a thicker wire. The wires of the fuseholder fit snugly between the large fuses to hold the fuseholder in place. I used a 3 amp fuse, plenty for most small LED bulbs.

To take the power from the little fuseholder to the DRLs, I used a two conductor 18 gauge wire from Home Depot- 62 cents a foot and rated to 90C. I only used one conductor, but wanted a wire with an outside sheath to protect it. I routed that wire to the passenger side turn signal area, then ran another length from there to the driver side turn signal area.

The easiest method to add DRLs to your car would probably be to mount separate standalone LED fog or DRL lights and connect to this new switched power feed.

A second pretty easy method would be to rewire your parking lights (the outer segment of your turn signal assemblies) so they use this switched circuit instead of going on and off with the headlights. You would want to use brighter LED bulbs for an effective DRL function.

I did a third method (modifying the turn signals by eliminating the inside amber lens, changing sockets, rewiring, and adding switchback bulbs) which is very cool but a lot of work. I'll post details on that in a second post.)

Anyway, that's an overview, maybe some folks will find this helpful.

I used one of these fuseholders

Amazon.com

I'll add some photos and a video.
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[centerpunch]

For my car, I wanted an integrated DRL solution, not add-on lights.

So I modified the turn signal housings to use switchback white/amber LED bulbs. Here's an overview of what is involved in doing that:

1) Note: If you’re ok with amber DRL you can skip this step.

If you want the DRL to show white, you have to remove the amber lens from inside the turn signal assembly so the white LED will project white. I did this using needle nose pliers through the bulb hole, but that is a huge pain in the ass. You also need to remove the metal heatshield to get the amber lens out. Both parts are very tough. I left the clear diffuser lens in place. If I were doing it again, I'd cut this turn signal assembly open like this guy did.

https://www.nsxprime.com/threads/diy-clear-front-turn-signals.218205/

2) You have to modify the bulb opening slightly so you can use a socket for a two circuit bulb (an 1157 instead of the original 1156).

I used these sockets

Amazon.com

3) Obviously, you have to wire the new sockets to both your existing turn signal wires (I just cut the old sockets off) and to the new DRL power.

4) Since the switchbacks are LED bulbs, your system will "hyperflash" (blink very fast). Since the LEDs use less current, the car assumes one of your bulbs is burnt out, and flashes fast to alert you. There are two ways to fix this. The easy way is to add load resistors in parallel with the LEDs, so they actually use the same current as a normal bulb. Another way is to remove the oem flasher, open it up, and modify it per the pdf in this post. (I did this, it's a pain. And note, I needed to use .3 ohms for my car.)

https://www.nsxprime.com/threads/le...ke-lamp-failure-solution.178540/#post-1754058

Anyway, hope this is helpful.

UPDATE: Please read post 12 in this thread- it has some good additions and caveats, and a link to bulbs that have built-in resistors.
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This sketch shows the parts inside the turn signal housing. I left the clear diffuser inside, but removed the metal part and the amber lens.


This last photo shows the new socket, with the blue wire attached to the new DRL power, and the red and black wire connected to the wires that used to go to the original turn signal socket. (After I took this photo I slid the heat shrink tubes up and heated them to seal over the soldered connections.)

 

[centerpunch]

PS If you live in some crazy country where they're real picky about how many lights can be on at once, you could easily wire a relay to the parking light wires to make the DRLs automatically go off when your parking lights or headlights go on.

 

[Wild Turkey]

Well done and great write-up! This will be a great help for future DRL additions. I'm going to add something similar.

Which "switchback" 1157 LEDs did you use? I haven't seen those before. Something like this? (It seems to have add-on resistors so you don't have to fiddle with the relay?)

LASFIT signature

I think this a video would really help to explain it. I just noticed for the first time that my OEM turn signals/markers blink differently (both together vs. alternating back and forth) depending on whether the running lights are on or not.

 

[centerpunch]

Which "switchback" 1157 LEDs did you use? I haven't seen those before.

I think these were the ones I used.

https://www.superbrightleds.com/catalog/product/view/id/202617/s/1157-switchback-led-bulb-dual-function-60-smd-led-tower-a-type-bay15d-bulb/category/2/

 

[I_M_Legend]

Nice write up. I recall reading somewhere that you could use the factory DRL connection by inserting the correct terminal into the head light connector. The car came pre-wired for DRL for the Canadian market or something like that.

 

[centerpunch]

I think this needs a video when you're done. I just noticed for the first time that the OEM turn signals/markers blink differently (both together vs. alternating back and forth) depending on whether the running lights are on.

I'm out of town for a few days, but will do that when I get home.

 

[Wild Turkey]

Oops, that came out a bit more gruff than I intended. I just wanted to be encouraging.

 

[centerpunch]

I think our cars need resistors. The bulbs with "canbus" fix built in are for newer cars with digital system to monitor bulbs. Our cars use old-school current sensing.

 

[centerpunch]

I think this needs a video when you're done. I just noticed for the first time that the OEM turn signals/markers blink differently (both together vs. alternating back and forth) depending on whether the running lights are on.

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[Wild Turkey]

That is awesome - thanks for the video! That's exactly what I'm looking for so I've ordered the parts. Thanks also for confirming that my wiring is correct, and that the signals are supposed to switch from synchronised to alternating when the running lights are on. Nifty, but I wonder why they went to that effort and didn't just have them alternate all the time.

I especially like how the DRL component of your switchback LED shuts off for a brief period after the signal component illuminates, to provide maximum contrast for the "off" portion of the signal. I've seen some that just go back to white when the amber is off during signal operation and the signal be hard to see in some low-viz conditions. This is much more noticeable with the Amber-Off switching. It's similar to a lot of newer cars that now shut off the headlight on one side when the turn signal is activated, if the headlight was on as a DRL, to maximise the turn signal contrast.

 

[Wild Turkey]

Great mod to add this DRL @centerpunch , while preserving a very OEM look and not compromising air flow to the AC! I think it will definitely improve our visibility, and not just for Silver and Black NSX's. I just finished it. Here's a video showing how the DRL "drops off" during signal operation to maximise contrast.

I would add the following notes for other folks doing this mod:

1. I used 18-gauge wire (overkill for the 0.4 A the two LED bulbs draw) with nylon sheathing. It fits easily beside the main wire loom and doesn’t require cutting the fuse box cover.
2. Be very careful running the wire for the DRL to make sure it does not interfere with the headlight retractor mechanism as it moves, especially on the right side. Also watch how the added lens wiring moves when you insert the lens back into the bumper. You can see it looking back if the headlights are "up". With some work you can tuck it under the existing loom and out of the way.
3. You can modify both the bulb holder and the lens each a little bit to accommodate the 1157, so it will still hold the stock 1156 assembly securely if you decide to go back, but probably the best way to go back will be to just use amber incandescent 1157 bulbs and pull the DRL fuse and/or the wiring, which would take ~5 minutes.
4. Totally agree on opening up the lenses externally to get the amber out vs pulling it out though the bulb hole. It’s impossible to get that amber portion out without opening it up and then re-epoxying.
5. I found these bulbs from amazon: Awesome! The white LEDs stay off for a period after the amber illuminates, to have maximum contrast during signaling but then go back to DRL operation shortly after the signal ceases. And they are BRIGHT.
6. Most importantly, the bulbs also have built in resistors with amber illumination so they DON'T require any additional external resistors or changes to the internal relay for normal turn signal operation.

Link for the bulbs I used:

Amazon.ca

Wiring that fits the fusebox without trimming the opening:

 

[Honcho]

You guys are doing some great work here.

 

[centerpunch]

You guys are doing some great work here.

It's kinda fun working out slightly improved mods for a car that was introduced over 30 years ago.

 

[Wild Turkey]

It's kinda fun working out slightly improved mods for a car that was introduced over 30 years ago.

I'd say more than slightly improved. This looks practically stock & fits the pre-2002 look way better than the add-on LED strips or even the CanDM "fogs" in the AC condenser venting. And, it doesn't make it harder for other drivers to see the front turn signals that are close to the LED DRL's.

 

[NSXnZ]

Thanks for this write up. Definitely one of the best things I did for the car. I didn’t want to cut my harness and was able to get a 1156 to 1157 adapter to wire in the DRL in case anyone doesn’t want to cut into the original harness.

 

[jsullyboy]

If you had the JDM clear turn signal lenses would this eliminate the step of cutting out the amber lens from the existing unit? Also do you know where the DRL module is located? I would like to see if I can install the module, fuse and run the wire off the factory harness.

 

[Wild Turkey]

Not clear what market you're working towards since it isn't in your profile. The Canadian model NSX's had ugly DRL's in the air conditioning condenser inlets, as shown in @Kozuchowski 's thread. Compare that to the videos above. Yes, if you have clear turn signal lenses, there is no amber to remove.

If you have a USDM model, you can't just add the DRL module (which may be discontinued) because some of the wiring is not there. @Kozuchowski just had a thread on this - a lot of work for minimal benefit. You'll have to run a ton of wiring all over the place (ebrake, ignition, headlight switch etc), for no real benefit. Just wire it as @centerpunch has shown in this thread. I'd recommend the bulbs I referenced above.

One other note. If you're doing this to get registered, you may not need to. Both of my NSX's each passed at least 2 safeties without issue because the mechanic thought the running lights were DRL or just didn't check that carefully. Since I had bought them both from Canadian owners, I had just assumed that the DRL's had been added by the previous owners, and only discovered the lack of DRL later.

Here's my thread on DRL's front & rear:

Solved: Motorcycle style Front & Rear Daytime Running lights - "Super DRL's"?

Done: See post 8. It seems everything on the road is getting bigger and we are getting harder to see. My search has turned up empty except a couple of threads on how many red/black wires you need to interrupt with switches to get the clock, dash, radio, and climate control to high intensity...

www.nsxprime.com

 

[jsullyboy]

Not clear what market you're working towards since it isn't in your profile. The Canadian model NSX's had ugly DRL's in the air conditioning condenser inlets, as shown in @Kozuchowski 's thread. Compare that to the videos above. Yes, if you have clear turn signal lenses, there is no amber to remove.

If you have a USDM model, you can't just add the DRL module (which may be discontinued) because some of the wiring is not there. @Kozuchowski just had a thread on this - a lot of work for minimal benefit. You'll have to run a ton of wiring all over the place (ebrake, ignition, headlight switch etc), for no real benefit. Just wire it as @centerpunch has shown in this thread. I'd recommend the bulbs I referenced above.

One other note. If you're doing this to get registered, you may not need to. Both of my NSX's each passed at least 2 safeties without issue because the mechanic thought the running lights were DRL or just didn't check that carefully. Since I had bought them both from Canadian owners, I had just assumed that the DRL's had been added by the previous owners, and only discovered the lack of DRL later.

Here's my thread on DRL's front & rear:

Solved: Motorcycle style Front & Rear Daytime Running lights - "Super DRL's"?

Done: See post 8. It seems everything on the road is getting bigger and we are getting harder to see. My search has turned up empty except a couple of threads on how many red/black wires you need to interrupt with switches to get the clock, dash, radio, and climate control to high intensity...

www.nsxprime.com

I am in a similar situation. I purchased the car in Canada and it was already imported but drl was never added. Unfortunately the shop doing the safety of my car knows the cars and won’t pass it without a drl solution.

 

[centerpunch]

Assuming Canada allows either white or amber DRLs, you could use the turn signal housing as is without removing the internal amber lens.

Then you just run a wire from the fuse, swap to different sockets and bulbs, file the socket opening slightly (all detailed above and in my video) and you’d be good to go.

Or maybe even easier, just add a pair of small led fog or drl lights and run a wire from the fuse.

Super easy job. If you’re not comfortable doing it, I think any car stereo place could do it.

 

[Wild Turkey]

If you just run the extra LED/fog or DRL lights, they won't shut off when the turn signals are operating, making it harder to see your front turn signals for oncoming traffic. That's why the switchback LED's are such a good solution. I believe most cars in last few years have incorporated this DRL suspension when the turn signals are active, for maximum contrast and visibility of your turn signals.

Any solution that reduces the effectiveness of the front turn signals is sub-optimal in my opinion - which was highly reinforced at NSXPO last year. While driving in a group, I couldn't see the turn signals of some NSX's that were following me because the LED strip-style DRL's were so bright.

 

[jsullyboy]

Great mod to add this DRL @centerpunch , while preserving a very OEM look and not compromising air flow to the AC! I think it will definitely improve our visibility, and not just for Silver and Black NSX's. I just finished it. Here's a video showing how the DRL "drops off" during signal operation to maximise contrast.

I would add the following notes for other folks doing this mod:

1. I used 18-gauge wire (overkill for the 0.4 A the two LED bulbs draw) with nylon sheathing. It fits easily beside the main wire loom and doesn’t require cutting the fuse box cover.
2. Be very careful running the wire for the DRL to make sure it does not interfere with the headlight retractor mechanism as it moves, especially on the driver’s side. Also watch how the added lens wiring moves when you insert the lens back into the bumper. You can see it looking back if the headlights are "up". With some work you can tuck it under the existing loom and out of the way.
3. You can modify both the bulb holder and the lens each a little bit to accommodate the 1157, so it will still hold the stock 1156 assembly securely if you decide to go back, but probably the best way to go back will be to just use amber incandescent 1157 bulbs and pull the DRL fuse and/or the wiring, which would take ~5 minutes.
4. Totally agree on opening up the lenses externally to get the amber out vs pulling it out though the bulb hole. It’s impossible to get that amber portion out without opening it up and then re-epoxying.
5. I found these bulbs from amazon: Awesome! The white LEDs stay off for a period after the amber illuminates, to have maximum contrast during signaling but then go back to DRL operation shortly after the signal ceases. And they are BRIGHT.
6. Most importantly, the bulbs also have built in resistors with amber illumination so they DON'T require any additional external resistors or changes to the internal relay for normal turn signal operation.

Link for the bulbs I used:

Amazon.ca

Wiring that fits the fusebox without trimming the opening:
View attachment 184078
View attachment 184079
View attachment 184080

Do you have a link to the inline fuse holder you used and the fuse type?

 

[Wild Turkey]

https://www.amazon.ca/Pack-AWG-Inline-Fuse-Holder/dp/B0B3J33H38/ref=sr_1_1_sspa?crid=1TFJ207K2UZGC&dib=eyJ2IjoiMSJ9.wrzysw-xVq-hEhDcWCG9cFrxsZAR_a3j5BB_VXlZFbWn0LcvNFfR9kSwcpxvpwS39kixq7md0uf4lAZPUGMIW5MNEGul5_9J3X8vk1ks3fJIASgHuLRfIce7U1C_YLN58g4lypY9aglmZzCrfurmH_k7uCJBKcT2LNL5CTNefjPM_UEHVVVFq4ndO20wyQ1J8AuA9U59pP1mPWMzkrK1eAgVmPr6VMJci7bNe-pJNoqNqb1nwU-p6ToqVgfCKFnQNIyObi3bljJXh08uDzgBiA7BzMZObXEOHp8K774_JJs.qMNKCg_bdG9oypBM3M0hFaGaNXSVyPGJG1D25QFAePg&dib_tag=se&keywords=fuse+holder&qid=1710897105&sprefix=fuse+holder%2Caps%2C97&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

2 A fuse.

 

[jsullyboy]

https://www.amazon.ca/Pack-AWG-Inline-Fuse-Holder/dp/B0B3J33H38/ref=sr_1_1_sspa?crid=1TFJ207K2UZGC&dib=eyJ2IjoiMSJ9.wrzysw-xVq-hEhDcWCG9cFrxsZAR_a3j5BB_VXlZFbWn0LcvNFfR9kSwcpxvpwS39kixq7md0uf4lAZPUGMIW5MNEGul5_9J3X8vk1ks3fJIASgHuLRfIce7U1C_YLN58g4lypY9aglmZzCrfurmH_k7uCJBKcT2LNL5CTNefjPM_UEHVVVFq4ndO20wyQ1J8AuA9U59pP1mPWMzkrK1eAgVmPr6VMJci7bNe-pJNoqNqb1nwU-p6ToqVgfCKFnQNIyObi3bljJXh08uDzgBiA7BzMZObXEOHp8K774_JJs.qMNKCg_bdG9oypBM3M0hFaGaNXSVyPGJG1D25QFAePg&dib_tag=se&keywords=fuse+holder&qid=1710897105&sprefix=fuse+holder%2Caps%2C97&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

2 A fuse.

Thanks

 

[centerpunch]

Using skills and/or magic, I shortened that link.

https://www.amazon.ca/Pack-AWG-Inline-Fuse-Holder/dp/B0B3J33H38