Brake Light Mod?

Hey Guys

I have a posted related to this on in the Technical Forum. But I haven't gained any traction on that post. https://www.tacomaworld.com/threads/assistance-from-the-electrical-tecs-please.713212/

I have searched fairly extensively. And I haven't ran across any threads similar to what I want to do. I've seen all the posts related to tapping the rear break light. But I would like to find the circuit inside the cab for the Center Stop Light.

Has anyone seen any similar posts?

Thanks
Randy

 

Just incase anyone is interested. I updated mp post in the above link.
Thanks

 

You try the rocker panel?
Zim

 

I finally found what I was looking for. The plug containing the Center Brake Light circuit "is" located behind the driver side kick panel. The Cargo Light circuit is also located in this same area. But it resides on a different connector body.

The mod that I am researching doesn't seem to be very popular. Not much information to be found on the way that I propose to approach this mod. I recently purchased a new Leer 100XR topper. And eventually I plan on removing the aftermarket electrical installation. And connecting the new 3rd brake light to the OE Center Brake Light electrical system. Also refeeding the Leer Dome Light with the OE Cargo Light circuit. I will update this thread shortly with all the drawings I have found so that anyone else interested in this mod can follow.

 

Just for prosperity, I'm going to update this thread with my findings thus far. I understand that this mod takes considerable more effort to complete than just simply tapping the rear tail light assembly. And that is probably why this mod isn't as popular. But sometimes it's the little things that make a mod really stand out. And I also have a couple other goals in mind that this mod will fulfill. My shell was only recently purchased. And not expecting delivery for several weeks. So I'm taking this time to organize the process.

1) I want to retain the little flicker dance that the Center Stop Light does every time you step on the brakes. I know that there is an aftermarket flasher that will do something similar. But, since this function is already built into the truck.

2) I want the Cargo Light Circuit to power the Leer cargo light. (If you already have a OE cargo light in the bed, well, your lucky).

3) I'm considering completely severing the connection to the Center Stop Light / Cargo Light. There is no need for it to operate with the canopy blocking the fixture. The new Leer fixtures will serve the same purpose.

So here are the drawings needed to find and use the Center Stop Light Circuit. I haven't physically went out to the truck to verify any of this information as of yet. And I will verify the operation with a DMM before making any alterations.

The OE Center Stop Light Circuit drawing designates the connector body, connector body pin number and the wire color.


The Connector Body drawing will give you a better ideal of what the connector looks like and where the pin location will be.


The Connector Body is found on the Main Body ECU.




Location of the Main Body ECU

 

Now the Cargo Lighting Circuit. Same as before. The drawing indicates the connector body, pin number and location. And the wire color.


Reference to the shape of the connector bodies and the pin location. Not sure which one is which - yet.


Reference to the location of the connector body.


I will update this thread when I start the wiring install. I'll verify the pin locations and circuit functions also.

 

On the cargo light, there is also wiring for the Toyota bed lights neat the taillights.

I've already clipped in my bed light in this photo.

 

On 3rd stop light flashing, I need to look at that one!

Power is direct brake light to the third tail light, so if there is a strobe function I would think it's built into the tail light itself. The same power is used for combo stop/tail. Some OEMs run a separate wire from the BCM (Body Control Module) which does that function.

When you are looking at Toyota wiring diagrams they play tricks with your minds. Old days we had fifty gazillion wiring diagrams, oh my.

These days they show one, but alternate wires depending on vehicle as built.



So from pin 8 of 1F there is only one wire.

BE (Beige) or (SB (Sky Blue) is used.

I'm looking at the 2021 Tacoma Manual, hence the notes.

 

The *2 & *3 show some harnesses had the two bin connector C15A; Some Harnesses have a four-pin connector C15B

*2 No cargo light
*3 Cargo light

I'm starting to think there is no strobe feature to the third tail. So save time and run wiring from just the tail light connector.

 

Just adding C15B Center Stoplight. Hence why four connectors. Power for Stop, Cargo, ad two ground wires.

 

Hmmm I’ll have to look there is a guy naming a harness do do this. Just noted he’s making a second gen version. may save some time if interested.

 

The third generation would be welcome. RSI is shipping a harness, but it's messed up since it is missing the tail light function. Doh!

 

the guy making it first started on 3rd gen then making the 2nd gen. Seup to do brake light but can splice out for parking, signals etc. ill have to find the thread

 

here you go: https://www.tacomaworld.com/threads/plug-and-play-brake-light-taps.707529/page-13#post-25377933

 

I know that some models all read have a cargo light in the bed. I was wondering if the wiring may be there on my truck. I'll have to take a look.

The drawings that I posted do show the wire coming directly from the BCM. I referenced the plug body and pinout on the BCM page. Your drawings show this too. The gray box where [1F and 1H] is the BCM.

I'm not really interested in the connector to the Center Stop Light itself. I don't want to deal with the headliner.

 

I have limited documents but was hoping to see more detail about the BCM.

I suspect I have a dumbed-down TIS (only some chapters) as no details about BCM or ECM. Frustrating.

I missed this was the BCM pass-through (doh!).

Ford manuals did a great job of detail of the CAN and LIN Bus.

 

That one took me a whole day of searching also.

I have a 2016 - 2019 ??? Copy of the drawings and assorted other documents that I found links to on Tacoma World forum about a year ago. They seem to be very thorough. Wish I could find the links again.

 

My shell has been installed for a couple weeks now. Finally had some time (and good weather) to start investigating the mods that I want to do.


I was surprised to find out just how inaccessible the Main Body ECU really is. Pulling the kick plates is relatively easy. But I would need to pull the knee plate to get 100% verification on the brake light circuit. I decided not to pull the knee plate. So, I decided to look at other areas of the harness where I might be able to make a "guess" at which conductor is the circuit in question. The harness is pretty big underneath the floor plates. So I decided to look at the harness in the back seat area and try to find the portion of the harness that divides and extends up the rear column of the truck on it's path to the Center Stop Light. I figured that I could reduce my chances of picking the wrong wire if I could localize the circuit to this portion of the harness. And that Is when I got lucky.



@roundrocktom It appears that the ECU does NOT have anything to do with the strobe function of the Center Brake Light. I confirmed this finding with a DMM. This little gizmo is "cut" into the harness (almost looks like an afterthought).


(Don't bother researching the PN. I already tried. Looks like it's the PN for the shrink-e-dink). The brake light circuit has been severed in this area. Male and female barrel plugs have been crimped onto the conductors and flasher is simply plugged in. I'm hoping to locate the Cargo Light circuit in this same area and do the same procedure. This falls directly in-line with my plans to disable the center light all together. I've started running new conductors for this mod and the new LED tape lights that I'm installing inside the new shell. But I did run out of time on advancing the investigation for the Cargo Light. So I'll continue this post next oppertunity I get to move forward.

SIDE NOTE: I've been contemplating a mod for the guys who remove their shells often. It should be possible to splice these circuit across a couple of standard automotive relays. This would offer the availability to convert from "Stock Lighting" to "Mod Lighting" with a simple flip of a switch. If anyone is interested, let me know and I'll draw something up.

 

That is bizzare!

This doesn't appear in the 2021 FSM. Body Control Module shows a Violet (V) wire to the lamp. Your harness has Red/Yellow going to the "thing".

Toyota has driven me crazy with "substitution color" (super rare, but if they run out off Violet you may find another color used for the circuit). I've seen that historically, but haven't torn into wiring harnesses in a few years.

 

Full Disclosure: The "severed" circuit is Violet (V). The flasher is wired like a Photo Cell. Can't remember exactly which wire is which. But one is INPUT. One is OUTPUT and one is GROUND.