OEM LED Headlight Conversion Harness

This harness is offered in two forms. Orders can be placed by following the link at the top and bottom of this post.

Ordering

Base Conversion Harness
With Grille Lights

Installation Videos
Chloe
Eric
How to connect eBay grille lights

Troubleshooting Guide

If you need a tap for MESO v5 mirror turn signal switchbacks or one for a switchpros, please let me know via DM for now. I will add those as options in the future to the items listed above.

If you need special consideration for some reason and square isn't possible for you, you can send me a DM.

NOTE2: The DRL signal does not engage until your parking brake is off. This is the same behavior for halogen and LED headlights. I found it confusing myself as have several others.

1. A standard TRD OEM LED conversion harness which is available from several alternative locations. The harness I produce has a few very minor differences noted below but is functionally equivalent to all of the others.

• I use labels on each wire (this is time consuming) to identify the wire's purpose and aid documentation and understanding. Since the high and low beam connectors are identical, this can help with the installation as well.
• I use 3.5" of PVC tubing to keep wires together instead of loom or braided sleeving. Mostly because I like the tubing better than sleeving and loom.
• I use high quality TXL wire from a very specific supplier as I like the colors, the quality, the copper strands, and the extra protection.
• I use OEM spec connectors with OEM part numbers for the DRL and Turn signal connectors. This decision costs around $10 more than using generic connectors. Technically, plastic is plastic and the connector either works or it doesn't work but to me a $1500 set of headlights demands the best possible connector available.
• I use white with a blue stripe for the low beam wire on the passenger side and white with a red stripe for the low beam wire on the driver side. The OEM harness uses solid blue and solid red respectively. I use white with a blue stripe to disambiguate with the other solid blue wire on the passenger side used to carry the parking light signal. This decision is mostly an aid for me when building the harness to avoid mistakes. However, there is also some pleasant aesthetic symmetry with the ground wire (white with black stripe) and their location on the MX-150 connector.
• I use OEM color scheme for ground wires, white with a black stripe, and I go up to 16 gauge on the ground given that it's a common ground for the other 5 signals. Sizing up on gauge is purely for my own personal satisfaction, 18 gauge is already oversized for a 7" length, but it feels to me like the ground should be one size larger, gauge-wise, than the 5 positive wires who rely on it.

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2. A blend of two existing concepts, a standard TRD OEM LED headlight conversion harness (described above) and a DRL Grille Light harness. It is modular, allowing taps of DRL and/or Parking Lights to feed alternate sources. It includes a standard adapter to combine DRL and Parking Light triggers using diodes to feed grille lights so you are prepared for the rapture. Additionally, this style allows an optional feed for MESO v5 switchback mirror turn signals.

At this point in time, only the TRD harness is available for purchase it this thread. So you must own a Sport, OffRoad, Limited or Pro which came with halogen headlights.

If you own an SR or SR5 and want to add OEM LED headlights, this is your thread.

If you order the "Without Grille Lights" harness, what you receive is pictured below:

• One driver side conversion harness
• One passenger side conversion harness
• Two caps for your unused sidemarker connectors

If you order the "With Grille Lights" harness, what you will receive is pictured below:

• One driver side conversion harness with 3 position AMP female connector to provide DRL, Parking Lights and Ground.
• One passenger side conversion harness without any additional taps.
• Two caps for your unused sidemarker connectors
  
• One 3 position AMP male to 2 position AMP female harness with integrated diodes.
• One 2 position AMP male with bare leads
• One 2 position AMP male with plugs (so you can do grille lights later or remove them)
• Two solderless butt connectors to connect the bare leads if your grille lights do not use a 2 position male AMP to connect.

I also include 2 blue and 2 orange fender flare clips as I'm able to keep them in stock (currently OOS on those but I have re-ordered). The extra clips only help if you break one of them during the installation. Since installing headlights on a third gen Tacoma requires dropping the front bumper to access one of the bolts, the front fender flares must be partially separated from the front bumper and that is where it is possible to break one of the clips.

If you already own an OEM LED conversion harness and just want a DRL grille light tap, you can purchase that from Running4Tacos or I will (on a case by case basis) make one for you. If you want a completely plug and play grille light option without using heat shrink butt connectors, R4T is the only one I know of. My kit requires connecting red to red and black to black to mate the pigtail connector to the grille lights of your choice.

If you already own a grille light harness and want to convert to OEM LED headlights, you can keep it as is or you can convert to my integrated solution and resell the DRL grille light harness to someone else.

NOTE: Installation should be as straightforward as I'm able to make it but you can mess up and swap low beam and high beam as well as get polarity wrong on either. Please do your best to match up to the correct connector. The high beams have 2 wires and are an exact color match. The low beams have one wire and are white with the corresponding color match as a stripe.

NOTE2: Some have reported trouble (3 people so far) exclusively with the passenger side. I just got done with a troubleshooting session with the third guy today and by removing the harness and replacing it the problem went away. I suspect there is some confusion about the force needed to properly seat the h9 connectors. Since the high beam provides the ground for the entire headlight, this could manifest as flickering or uncertain behavior in the headlight itself. I select the h9 male connectors specifically for a tight fit with the OEM H9 female connectors. But with that said there is no OEM spec for male H9 connectors as the intent is for the female connector to seat directly on the bulb. Therefore, other conversion harnesses may fit looser or differently. I much prefer how the H9's fit but they do require some force to seat properly. Pay extra attention to these 4 connections particularly the high beam, make sure it's correct and fully seated.

You have multiple options for OEM LED conversion harnesses. I try to keep a running list of them in the OEM LED Harness DIY thread for anyone who wishes to shop around and compare/contrast.

 

Photos of the product (NOTE missing H9 connectors at the time these photos were taken, your harness will have all required connectors and will be fully plug and play.)

Without Grille Lights:


With Grille Lights:


More details on how these are built:
This module combines DRL and PARK signals using 1 amp diodes to feed a constant +12V whenever either is on. The module on the far right is an early prototype.

This is a detailed view of the driver side

This is a detailed view of the passenger side

This is the new diode module for combining DRL and parking light signals to a constant ON whenever the stalk is not OFF


Installation:

The DRL and turn signal connectors only fit one way so they are not possible to get wrong. Make sure you hear an audible click and that you can’t pull them apart. The sidemarker caps are fully independent and meant to form a watertight seal with the sidemarker connectors which are not used with the LED headlights.

The high and low beam connectors, however, are possible to get wrong. I’ve started placing heat shrink labels on these to make the installation easier.

The trick is to color match the wires noting that low beams on my harness are white with a stripe matching the solid color wire on the OEM harness. Here is an example of how it looks when properly connected.



The ground for the entire assembly is off the high beam connector. It is essential to get that connector oriented properly or nothing will work. This is a little tricky with the driver side where positive is solid white and the ground is white with a black stripe.

Here is an example of what not to do. Notice how the yellow + wire and white / black ground are swapped. Also notice the exposed tab. If you do this by mistake, unplug and flip it around.



How to connect eBay grille lights
Video instruction on how to use heat shrink butt connectors.

 

yeah, maybe if you want to risk getting left behind!

 

Awesome!

 

NICE

 

Well done, Dave! I need this harness in my life. I figure if I purchase the harness and leave it lying around in the garage for a little while, then I'll have no choice but to purchase the LED headlights and install everything.

I'll send you a PM.

 

Troubleshooting guide

1. Check to make sure all connectors are fully seated (audible click) and not kinked or sliced against metal, not smashed into a corner, etc. If unusure, disconnect, visually inspect for any debris or shards of plastic/rock/etc and then reconnect. You should be able to recognize an audible or tactile "click" when fully seated.
2. Check to make sure none of the terminals have pulled out of the connector. This can happen with excessive force or if, for some reason, they were not properly seated originally. If this happens, try to push it back in (firm but not excessive force, ensuring proper terminal alignment) and if you're still stuck, reach out to me for help via DM with photos.
3. Double-check all of the black H9 male connectors. The latest version of the harness has color matched green and yellow heat shrink on them to match up to the green and yellow inserts. H9 and H11 connectors look deceptively similar, green is H11 and yellow is H9. So you match up green to green and yellow to yellow to ensure the high beam on the harness is matched to high beam from the truck and vice versa for low beam.
4. Double-check each individual black H9 male connector for polarity. The wire colors on both sides should be an exact match. Pay extra attention to the driver side high beam which has solid white for positive and white with black stripe for ground. All grounds are white with black stripe. Only the high beam connectors on the conversion harness have a ground, low beam has no ground since the OEM LED headlight assembly only needs one ground and we take from the highest rated circuit (high beam) to supply it. You'll also notice that the H9 males have retaining tabs at different height, matching the OEM female curves, this is yet another visual aid to guide proper polarity. Finally, note low beam and high beam are pinned opposite on Toyota's side so they are correspondingly different on the conversion harness. Polarity does not matter for halogen bulbs but it is necessary to get polarity right on the OEM assembly or it won't work.
5. Double-check your fuses in the engine bay fuse box (DRL, High x 2, Low x 2) and in cab fuse box (Parking Lights) if you observe a failure of one or more specific fused circuits. My harness should not have any way to short power to ground, it'd float instead since there is only one ground. However, this is an easy step to rule out issues and worth the time to confirm.
6. NOTE: The DRL circuit on most Toyota vehicles does not engage until the parking brake is released once ignition is on. This is a little confusing until you see it in action. The ECU sends the DRL signal when the stalk is in DRL mode or Auto mode and the ambient light sensor detects adequate outdoor light. The DRL signal is also present when parking lights are on if low beams are not on, note AUTO will turn on low beams when low ambient light is detected. Proper DRL is a bright white "C" on both headlights which you should see for DRL and Parking Lights without low beams. Meanwhile with low beams on you'll have Parking Lights and no DRL which is a dim "C" as well as the sidemarker and lower 3 led's in front (along with the low beam). If you are in parking light only mode (low beams off) you should see a bright C since DRL is still "on" as well as sidemarker and lower 3 lit up which I call DRL + Park.
7. If you still have trouble at this step, swap driver and passenger sides. They are symmetrical but the wire colors won't line up. So, if you do this, yellow on the passenger side for high beam positive will now feed white on the conversion harness and vice versa on the driver side (white feeds yellow). Also the low beams will be blue to red and red to blue. Now re-test and you should either see the problem stay on the same side or move to the other side. If the problem follows the harness that points to either a problem with the harness or a problem connecting the harness to the truck. We've had one problem which was resolved with a new OEM female H11 connector, I really didn't see it or understand it but I was happy to get things resolved. If the problem stays on one side it's most likely a bad assembly or potentially some trouble with the truck's wiring.
8. If you still have a problem, reconnect the halogen headlights (you can rest them on towels on top of things in the engine bay, make sure you don't short any battery terminals) and confirm your testing methods. Then reach out to me with photos and a full description of your observations via DM and I'll help guide further.

If there is a problem with my harness that is not due to abuse I will replace it at no charge. And if there is a problem that is due to abuse or crash, I will still replace it and we'll just see, based on the circumstances, what the proper cost should be. I'm pretty generous in this respect but I don't like to be taken advantage of so just be open and honest and we'll get the problem resolved.

 

Sounds good (sorry, I was sending you a PM as you were sending me this). Tomorrow might be tight with my work schedule, but I'm not going to rule it out just yet. Shoot me a text and let me know what time you're planning to come up this way.

 

Am I reading this correct that this harness will allow you to convert to the 2020 LED Pro headlights and also tap off the DRL to run grill lights? I know the harness that Running 4 Tacos sells says it would not work with 2020 LED Headlights.

 

100% correct on everything.

 

@daveeasa How to I order sir

 

Bottom link in first post.

 

@daveeasa done

 

Just wanted to double check that I don't have to have connect those famous grill lights for this harness to work? I just want to convert the halogen lights on a 2021 TRD Sport to the TRD Pro Led lights.

 

So here is the deal on people who aren’t scared of the rapture.

I will sell you my harness with no grille light tap. I am ok with that. But it’s basically the exact same thing as what Mike is providing. And that makes me feel like a jerk. Similarly I would feel like a jerk selling a DRL tap for grille lights since R4T has that. At least with the two combined I can fool myself into thinking my product is different enough to relieve whatever guilt I feel.

So, maybe what I can do is an off menu option for $85 with no grille tap? That’s what I offered @KrnTaco08 so I guess I should extend it to others.

Out of curiosity, though, why buy from me instead of the other options I list in the DIY thread?

 

After reading through that other thread, I see that you are very responsive and super helpful to people. I'm always willing to pay more for great customer service. Plus I'm just a YouTube mechanic so if I run into any problems it's nice to know that there's someone responsive that will answer my questions.

 

Here Here. I was about to ask the same question if you would provide the "Mike" harness as an option for those of us not planning on doing grill lights. Your harness seems to be well built and having someone on the other end to reach out to incase something goes sideways has a lot more value to us DIY'ers.

 

I appreciate that. Please know any help/advice I give is free. The harness stuff I do is purely for meditative relaxation when I can’t sleep late at night or early in the morning. I consider it my male knitting.

I’m also totally happy to help someone out who buys the eBay product and wants sidemarker caps for $10. I’ve done that for a couple of people.

But I’m definitely happy to help out informed buyers actively selecting my stuff for reasons like yours at the $85 price with no grille light tap.

I plan to add a waterproof cap to the base product for times when someone does not want to use the grille light tap. Should have those extras next week.

If you’re sure you don’t ever want grille lights, it’s a bit cleaner to just do a straight set with no tap.

It looks like I didn’t take a photo of the set I sent to @KrnTaco08 but maybe he can post a photo once they arrive. I’ll be able to make more once I get the DRL connectors which shipped on Friday, I had ran out of those.

 

Awesome! Filling out the form now. Oh and yes, I'm completely sure I don't want those grill lights. Also, totally cool waiting for those extra parts to arrive since my truck just started it's journey from Mexico and is still somewhere in the middle of the Pacific Ocean.