Hey everyone, in this thread I will show how to move the front turn signals to the front marker lights location and run both the marker lights and the turn signals through the SAME bulb. This method will effectively turn your new lights into dual filament bulbs, without drilling into the housing, and will give the most stock looking marker/turn signal possible.

The stock turn signals are located in the front bumper. If the stock bumper needs to be removed, the turn signals have to be incorporated into either an aftermarket bumper or by some other way. When I designed my steel bumper, I did not want the turn signals to be part of the bumper. In order to keep a clean stock look, moving the turn signals to the marker light locations was the best choice for me.

Before this mod, there were three ways to incorporate the turn signals into marker lights.
(1) Replace the marker light bulb with a dual filament bulb. This method gave a clean look, but required drilling the housing and using silicone to make everything waterproof. If the bulb needed to be changed, the silicone had to be chipped off and re-applied. (01-04 Blinker Relocation Mod | Tacoma World)
(2) Drill the housing underneath the marker light location and install the turn signal in the new hole. With the turn signal lower in the housing, it is not in an ideal location to reflect and may have adverse lighting characteristics. (Turn Signal Mod: Aftermarket Bumper ~WRITE UP~ - Toyota 4Runner Forum - Largest 4Runner Forum)
(3) Clip the positive from the turn signal, the ground from the marker light, and connect the two together. This method is called the Floating Ground Method, and doesn't require drilling into the housing, but the turn signals and marker lights must be the same brightness. There can also be feedback issues when using the turn signals with the marker lights off. I believe this method is also technically not DOT legal because the marker light flashes off (instead of brighter) when the marker lights and turn signals are on.


In THIS mod, we are changing the circuit configuration to as follows:



In this configuration, both the turn signal and marker light run through the same bulb, WITHOUT drilling, AND act like a dual filament bulb.

Note: This mod can also work on other vehicles. I provided my math at the bottom of this post on how I determined the best resistor value, so if your vehicle uses different lights, you can determine what resistor will be best for your application.

Supplies:

- Four Diodes (3 Amps) ( https://www.amazon.com/Install-Bay-D...r=8-2-fkmrnull )
- Two Resistors (4.7 Ohm, 10 Watt) ( https://www.amazon.com/uxcell-Power-...gateway&sr=8-3 )
- Two 921 Incandescent Mini Light Bulbs ( https://www.autozone.com/electrical-...ulb/165375_0_0 )
- 18 gauge wire
- Weatherproof Butt Connectors ( https://www.autozone.com/ignition/el...archText=85244 )
- Heat Shrink (various sizes)
- Soldering Kit
- Heat Gun
- Wire Strippers & Crimp
- Screw Driver (both Flathead and Philips)
- Towel


Step One:

On a work bench, connect 18 gauge wire, resistor, and diodes in the following configuration:


Solder everything together, and then use heat shrink and the heat gun to seal everything up.

Step Two:

Open the hood and remove the top screw holding the marker light. Insert a flat head screw driver (covered with a towel to protect the paint from scratches) and pry on the housing moving it forward. Remove the the bulb from the housing by turning the terminal counter clockwise and pulling it straight out.



Step Three:

Cut the positive lead to the marker light about 3" from the light. Cut the positive lead to the turn signal as close as possible to the light, leaving as much wire length as possible and route the wire to the marker location. Connect all of the wires according to the new wire configuration. Use the weatherproof butt connectors to connect everything. Remember to crimp the butt connectors and use a heat gun to seal everything up.


*in the photo I lengthend the ground wire. This is not necessary, but it will help to make more room

Step Four:

Remove the stock 2825 mini bulb, and replace with the new 921 incandescent mini bulb. The base may have a little difficulty holding the light, if so, use a mini Flathead screwdriver to bend the pins in the base inward.



Step Five:

Install the bulb and base back into the housing. Snap the housing back in and screw the top. Repeat with the other side.


Now your marker/turn signal lights will perform as follows:

Marker Lights on


Marker Lights off, Turn Signal on


Marker Lights on, Turn Signal on


*There are a few drawbacks to using this method*. This resistor value ONLY works with the 921 bulb, so if you want to switch to an LED or another light later on, you will need to re-wire everything. Also, the 921 bulb (being a larger bulb) takes a little longer to light up, so if you have a remote lock/unlock feature, the lights will flash very dim (because of the quick on/off flash, time is too short for the 921 bulb to light up). The 921 light bulb may be brighter than the stock 2825 bulb (264 Lumens vs 50 Lumens), but the bulb is not as bright as the stock turn signal bulb (465 Lumens). The new location is easier to see though (the marker housing is clearer than the old turn signal housing) and seeing it in person it looks plenty bright.

If you have another vehicle and need to determine the proper resistor value, or if you are interested in how I determined the resistor value, here is my math:


From this we find that a 4.49 Ohm resistor of at least 5.22 Watts is necessary. The closest commonly found resistor is 4.7 Ohms, 10 Watts. The lamp re-rating formulas must be used to determine the best resistor because incandescent bulbs resistance values change depending on the supplied voltage/current. More info about lamp re-rating can be found here: https://en.wikipedia.org/wiki/Lamp_rerating

The diodes should be chosen according the max current that passes through them. No more than 1.4 amps will pass through a diode, so these 3 Amp Diodes work just fine.


Hope this helps someone looking combine their marker / turn signal lights. If anyone has any questions, please comment. Thanks!

@Team_Jake

I want to do this mod but keep my original turn signal as well. I have the factory 96-98 bumper.

My plan is to follow your directions except to tap into the turn signal wire rather than cutting it. That should let the turn signal keep operating uninterrupted. Does that sound right?

Nice work

Good job, one thing to note though is that the light seems pretty dim and I don't like having a weak turn signal with how terrible some people drive. Using a 3157 switchback LED in a clear lens marker puts out a lot of light both in marker and signal form.

It does carry the drawback you wanted to avoid of having to glue the bulbs into the housing, but I've had the set in my truck for about 2 years hiccup free, and was able to easily remove the bulb and put it in a new light when I cracked a lens.

Just my .02

Sent from my JSN-L23 using Tapatalk

I believe that should work as long as you split the signal wire before the diode, otherwise your original turn signal light would be affected by the marker light.

Even though the bulb is more dim than the original turn signal bulb, it is in a more pronounced location with a clear housing. I haven’t compared mine side by side with a standard 3rd gen front turn signal yet but I would guess the brightness between the two is similar. Seeing it operate it person it looks plenty bright.

That said, I do like the idea of doing this mod with an LED bulb to get a little more brightness, but I don’t know what I would need to do though to have a dimmer mode for the marker light and a brighter mode for the turn signal, since the way LEDs operate are totally different from the way incandescent lights operate. I’m a mechanical engineer, not an electrical engineer, so if someone knows more of this kind of stuff I’d be eager to learn.

No diodes/resistors needed and the LEDs bulbs will be at full brightness in parking light mode wit these LED Switchback control modules VER.1 (for 1 color LED setup) | PAIR – CorsoMotion. I run them on my dad's CRV because the OEM turn signals are located at the inner corners of the headlights, pretty stupid placement since at some angles you can't even see them from the side. As for DOT legality I know some older GM vehicles use light assemblies that are both market and signal that use single-filament bulbs, so when the marker lights are on they flash off when signals are used.

One can also 3D print these adapters to allow using a 7440/7443 bulb socket in their corner lights 7440 Bulb Adapter by finallygotregistered - Thingiverse It appears you'll still need to open up the existing bulb opening though.

What does that product do? Their web site doesn't explain it.

It uses no 'additional' diodes or resistors Because they're already on the inside.

Kinda of pricey for what it is, just buy your own resistors for a couple bucks and wire in if you want to avoid the fast blink. Which I kinda like, it blinks and gets Everyone's attention, isn't that what we want?

This?



(I have the wiring schematic handwriting of a 7 year old, sorry bout that)

Converts single-function lights (like our corner lights) and makes it multi-function so it's now also a turn signal, without dimming the bulb down at all.
- Parking lights on, they're at full brightness.
- Parking lights off/signals on they blink in sync with the existing turn signals.
- Parking lights on/signals on they still blink in sync by flashing them off then on.

I just realized OP completely bypassed his bumper signals. These modules I mentioned will fast flash if you wire these in place of actual turn signals, they don't create enough of an electrical load.

Yes, that’s what I had in mind. Be sure to use the same resistors / diodes / bulbs I used.

@APhelps , you’re an EE, could you confirm this?
Jziggy wants to keep his turn signal functioning normally and his marker light to function like a dual filament bulb with a dimmer marker light and brighter turn signal light, basically do what I did but splice into the turn signal line rather than cutting it.

This can always be solved by changing out the turn signal relay with one that’s not load dependent. Any Auto Zone will carry these.

If you want do do that, connect the ground wire (white-black) from your current corner light to the turn signal positive wire instead of ground. It will flash with the turn signals when the lights are off and opposite the turn signal when the lights are on, like this (ignore the switchback main turn signal, focus on the corner light):

YouTube

I also put in a very bright LED corner bulb to help out with brightness there.

-Charlie

Charlie,

I like this approach. Can you help me understand from a wiring perspective why it works that way?

Which LED bulb did you use?