IND

Ryan@IND · 06-02-2015, 05:09 PM

Kohlenstoff Rear Diffuser Walkthrough

Up to this point, the aftermarket support for the F8X has been nothing short of stellar. Manufacturers and tuners alike have responded in a grand way and are delivering product to fill nearly everyone’s individual preferences. One such piece that was recently released is the Kohlenstoff LED equipped rear diffuser. Drawing inspiration from the circuit, this diffuser is equipped with a center mounted LED strip that is triggered by engaging the brake.

Below is a general installation guide for the Kohlenstoff rear diffuser. As always, we welcome feedback and alternatives. There are many ways to install components and the guide below provides insight into how our technicians remove these pieces. If at any point you do not feel comfortable with the installation process, then contact a body shop or your local BMW dealer for assistance.

Tools required:

Flat-head screwdriver
10mm socket
8mm socket
extension
ratchet or socket driver
nylon prybar

Step 1 – Remove Passenger Taillight

Step 1 - Pop the trunk and remove the plastic screw from the black cover between the taillight and trunk liner. (flat-head screwdriver)
Step 2 - With the screw removed from the plastic panel, remove this panel. This will show you the two 10mm nuts securing the taillights to the vehicle.
Step 3 - Remove the bolts with the 10mm socket
Step 4 - Now that the bolts are removed, the only thing securing the taillights to the vehicle is a round plastic tab. To remove this tab, carefully mask the outermost corner of the taillight. Protect both the paint and taillight. Take the nylon pry bar and lift the taillight using leverage.
Step 5 - Carefully pull the taillight away from the vehicle and remove the PnP connector on the back of the housing.

Step 2:
Now that the passenger taillight is removed, the next step is to feed the power and ground wire that will be used on the Kohlenstoff LED module. Feed the wire through the opening at the base of the passenger taillight area.

Step 3:
Work on feeding the wires through the passenger exhaust outlet. As you can see from the photos below, we draped them directly over the passenger exhaust tips. This will give you a good straight line connection to the Kohlenstoff module.

***PLEASE ENSURE THAT YOU HAVE PLENTY OF SLACK ON BOTH ENDS OF THE WIRES***

Step 4:
With the line in the correct location, it is now time to focus on the connections. You will be tapping into the PnP connector that connects to the rear passenger taillight. The two wires to focus on are the brown color coded wire and black/blue wire. Using two wire tap splice connectors, connect the red wire with the black/blue. After this is complete, use the second connector and mate the black wire with the brown wire. Photo breakdown below:

Red – Black/Blue

Black - Brown

Step 5:
Using two heat shrink sleeve connectors, we now focus on connecting the Kohlenstoff LED module with our black and red wires. Please be sure to rest the diffuser on an object that will not scratch the finish. Also, this is where a little extra slack is quite the luxury. This step is fairly simple. Strip the ends of the red Kohlenstoff wire and our red wire. Join these with the heat shrink sleeve connector. Now repeat with both black wires.

Step 6 - Removal of the factory rear diffuser

Step 1 – Using an 8mm socket, remove the BMW 8mm screws on the outside corners of the OEM diffuser
Step 2 – Gently pull back on the OEM diffuser one section at a time. This pressure will release the clips from the bumper.
Step 3 - Remove the 8mm bolts holding the center of the exhaust shield.

The below video shows this removal during the RKP diffuser install:

Step 7 - Install the Kohlenstoff rear diffuser

Step 1 – First, focus on clipping the center part of the diffuser into the factory slots.
Step 2- There are two bolts on both ends of the diffuser. Using the 8mm socket, tighten all 4 bolts (2 on each side)
Step 3 - Tighten the two center bolts

Step 8:

Before installing the passenger taillight, secure and protect all connections with electrical tape.

Step 9:
Install the PnP connector into the passenger tailight

Step 10:
Align the passenger taillight with the mounting tabs and push forward while applying light pressure.

Step 11:
Using a ratchet or drill install the two 10mm nuts. Then install the plastic cover with the rivet located at the top inside edge of the taillight.

Fellfromdsky · 06-02-2015, 11:04 PM

omg i need this diffuser lol

CaptBTKirk · 06-02-2015, 11:42 PM

Great write-up. Any worries that the exhaust tips will be hot enough to compromise the insulation on the wiring (apart from my own

?

evm3 · 06-03-2015, 06:48 AM

Thanks IND for the install , I was looking for a more unique part to set it apart from other m4's.
Now to concentrate on performance upgrades.

Ryan@IND · 06-03-2015, 10:10 AM

Quote:

Originally Posted by CaptBTKirk

Great write-up. Any worries that the exhaust tips will be hot enough to compromise the insulation on the wiring (apart from my own

?

We apologize, but we did not get a photo of the solution for this concern. The wire is tucked on top of the heat shield over the exhaust.

MCanadaE46 · 03-05-2018, 01:10 AM

Interested in this.

How complicated will it be to wire this up to turn on with the rear fogs?

I've done the LCI tailight upgrade and as well have done the emergency brake light mod (rear fogs flash during hard braking).

I'm not a fan of having them light up everytime I brake...but for emergency braking and for them to function as rear fogs it would much cleaner. Is this possible?

WatashiEd · 01-22-2019, 05:42 PM

Nice products as always IND!

Is there any aftermarket connector / harness that we can buy to avoid spicing the factory taillight wiring? Just a bit of OCD and doesn't want to do any permanent mod to the car, and I return the call to full stock condition if needed

skalberti · 01-25-2019, 03:22 PM

Quote:

Originally Posted by Nalen

Interested in this.

How complicated will it be to wire this up to turn on with the rear fogs?

I've done the LCI tailight upgrade and as well have done the emergency brake light mod (rear fogs flash during hard braking).

I'm not a fan of having them light up everytime I brake...but for emergency braking and for them to function as rear fogs it would much cleaner. Is this possible?

You can code this on. There's a DIY on the forum. You already have the button on your dash to turn the rear fogs on and off.

flexspec · 08-11-2020, 09:03 PM

So excited to have this diffuser installed. Of all the mods I have done, this one is the sweetest. Absolutely stunning!

M3nmotion18 · 08-20-2020, 03:35 PM

Iceweasel,

Diffuser looks great!

I might get this or 3D Design!!

flexspec · 02-24-2021, 09:35 PM

Quick update on the diffuser - looks much better with a proper exhaust setup. Also - I had the exhaust wrapper in clear XPEL PPF.
I have no other comments. Overall a well made product that fits well.

Kudos to @houstoncarenthusiast for the awesome pics

Cheers!!

airkenny · 06-11-2023, 02:54 PM

I've had these for over 4 years now and noticed quite a few led lights have died.

Any idea if there's replacement leds available? would hate to have to buy a whole new diffuser.

06-02-2015, 05:09 PM	#1
Ryan@IND 1765 Rep 7,650 Posts Drives: ACR Join Date: Mar 2008 Location: Chicago iTrader: (18)	IND \| Kohlenstoff Rear Diffuser DIY Kohlenstoff Rear Diffuser Walkthrough Up to this point, the aftermarket support for the F8X has been nothing short of stellar. Manufacturers and tuners alike have responded in a grand way and are delivering product to fill nearly everyone’s individual preferences. One such piece that was recently released is the Kohlenstoff LED equipped rear diffuser. Drawing inspiration from the circuit, this diffuser is equipped with a center mounted LED strip that is triggered by engaging the brake. Below is a general installation guide for the Kohlenstoff rear diffuser. As always, we welcome feedback and alternatives. There are many ways to install components and the guide below provides insight into how our technicians remove these pieces. If at any point you do not feel comfortable with the installation process, then contact a body shop or your local BMW dealer for assistance. Tools required: Flat-head screwdriver 10mm socket 8mm socket extension ratchet or socket driver nylon prybar Step 1 – Remove Passenger Taillight Step 1 - Pop the trunk and remove the plastic screw from the black cover between the taillight and trunk liner. (flat-head screwdriver) Step 2 - With the screw removed from the plastic panel, remove this panel. This will show you the two 10mm nuts securing the taillights to the vehicle. Step 3 - Remove the bolts with the 10mm socket Step 4 - Now that the bolts are removed, the only thing securing the taillights to the vehicle is a round plastic tab. To remove this tab, carefully mask the outermost corner of the taillight. Protect both the paint and taillight. Take the nylon pry bar and lift the taillight using leverage. Step 5 - Carefully pull the taillight away from the vehicle and remove the PnP connector on the back of the housing. Step 2: Now that the passenger taillight is removed, the next step is to feed the power and ground wire that will be used on the Kohlenstoff LED module. Feed the wire through the opening at the base of the passenger taillight area. Step 3: Work on feeding the wires through the passenger exhaust outlet. As you can see from the photos below, we draped them directly over the passenger exhaust tips. This will give you a good straight line connection to the Kohlenstoff module. *PLEASE ENSURE THAT YOU HAVE PLENTY OF SLACK ON BOTH ENDS OF THE WIRES* Step 4: With the line in the correct location, it is now time to focus on the connections. You will be tapping into the PnP connector that connects to the rear passenger taillight. The two wires to focus on are the brown color coded wire and black/blue wire. Using two wire tap splice connectors, connect the red wire with the black/blue. After this is complete, use the second connector and mate the black wire with the brown wire. Photo breakdown below: Red – Black/Blue Black - Brown Step 5: Using two heat shrink sleeve connectors, we now focus on connecting the Kohlenstoff LED module with our black and red wires. Please be sure to rest the diffuser on an object that will not scratch the finish. Also, this is where a little extra slack is quite the luxury. This step is fairly simple. Strip the ends of the red Kohlenstoff wire and our red wire. Join these with the heat shrink sleeve connector. Now repeat with both black wires. Step 6 - Removal of the factory rear diffuser Step 1 – Using an 8mm socket, remove the BMW 8mm screws on the outside corners of the OEM diffuser Step 2 – Gently pull back on the OEM diffuser one section at a time. This pressure will release the clips from the bumper. Step 3 - Remove the 8mm bolts holding the center of the exhaust shield. The below video shows this removal during the RKP diffuser install: Step 7 - Install the Kohlenstoff rear diffuser Step 1 – First, focus on clipping the center part of the diffuser into the factory slots. Step 2- There are two bolts on both ends of the diffuser. Using the 8mm socket, tighten all 4 bolts (2 on each side) Step 3 - Tighten the two center bolts Step 8: Before installing the passenger taillight, secure and protect all connections with electrical tape. Step 9: Install the PnP connector into the passenger tailight Step 10: Align the passenger taillight with the mounting tabs and push forward while applying light pressure. Step 11: Using a ratchet or drill install the two 10mm nuts. Then install the plastic cover with the rivet located at the top inside edge of the taillight. __________________ IND DISTRIBUTION \| 866-963-4520 • INSTAGRAM • FACEBOOK • FLICKR Last edited by Ryan@IND; 02-02-2016 at 02:51 PM..
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06-02-2015, 11:04 PM	#2
Fellfromdsky First Lieutenant 124 Rep 299 Posts Drives: 2020 M2c - 6 speed Join Date: May 2011 Location: Los Angeles iTrader: (1) Garage List 2020 BMW M2 Competi ... [0.00]	omg i need this diffuser lol __________________ Current: 2015 F82 M4 \| MW/SO \| M Performance Parts / KW Sleeve / Hüper Drei 35 / Blackboxguard / Stormtrooper valvestems Previous: 2011 e92 M3 \| SG/FoxRed \| ModeCarbon V2/ KW Sleeve/ Vorsteiner bootlid/ Arkym diffuser / Hüper Ceramic 15 Other Previous: F430, F355 & F328
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06-02-2015, 11:42 PM	#3
CaptBTKirk New Member 9 Rep 19 Posts Drives: 435i xDrive MSport Join Date: Dec 2013 Location: Washington State iTrader: (0)	Great write-up. Any worries that the exhaust tips will be hot enough to compromise the insulation on the wiring (apart from my own ?
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06-03-2015, 06:48 AM	#4
evm3 Second Lieutenant 56 Rep 236 Posts Drives: M4 + others Join Date: Feb 2011 Location: Great Lakes iTrader: (3)	Thanks IND for the install , I was looking for a more unique part to set it apart from other m4's. Now to concentrate on performance upgrades.
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03-05-2018, 01:10 AM	#6
MCanadaE46 Private First Class 150 Rep 163 Posts Drives: BMW M3 F80 Join Date: May 2015 Location: Toronto, Canada iTrader: (0)	Interested in this. How complicated will it be to wire this up to turn on with the rear fogs? I've done the LCI tailight upgrade and as well have done the emergency brake light mod (rear fogs flash during hard braking). I'm not a fan of having them light up everytime I brake...but for emergency braking and for them to function as rear fogs it would much cleaner. Is this possible?
	Appreciate 0 Quote

01-22-2019, 05:42 PM	#7
WatashiEd Second Lieutenant 29 Rep 270 Posts Drives: 2015 F82 M4 DCT Join Date: Mar 2016 Location: Sydney, Australia iTrader: (0)	Nice products as always IND! Is there any aftermarket connector / harness that we can buy to avoid spicing the factory taillight wiring? Just a bit of OCD and doesn't want to do any permanent mod to the car, and I return the call to full stock condition if needed __________________ Sapphire Black M4 \| iPE - Valvetronic exhaust \| VRSF 3″ catless dp \| Bootmod 3 Stage 2 \| OEM LED alcantara steering wheel \| OEM M4 GTS CF hood \| Vorsteiner GT wing \| M Performance CF splitter \| Vorsteiner CF front lip \| M Performance CF side skirt extension \| 3D CF diffuser \| OEM CF mirror cap \| H&R lower spring \| Rays Engineering TE37 Ultra Bronze 20x10F 20x11R
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08-11-2020, 09:03 PM	#9
flexspec Second Lieutenant 367 Rep 257 Posts Drives: F80 M3, E90 330i Join Date: Nov 2012 Location: Houston, TX iTrader: (4)	So excited to have this diffuser installed. Of all the mods I have done, this one is the sweetest. Absolutely stunning! Attached Images Last edited by flexspec; 08-13-2020 at 11:23 AM..
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08-20-2020, 03:35 PM	#10
M3nmotion18 Captain 390 Rep 656 Posts Drives: 2018 IR ZCP BM3 Join Date: Aug 2018 Location: Seattle, WA iTrader: (1) Garage List 2018 BMW M3 [9.87] 2021 MINI COOPER [10.00] 2023 GENESIS GV60 [10.00] 2017 LEXUS RX350 [10.00]	Iceweasel, Diffuser looks great! I might get this or 3D Design!!
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02-24-2021, 09:35 PM	#11
flexspec Second Lieutenant 367 Rep 257 Posts Drives: F80 M3, E90 330i Join Date: Nov 2012 Location: Houston, TX iTrader: (4)	Quick update on the diffuser - looks much better with a proper exhaust setup. Also - I had the exhaust wrapper in clear XPEL PPF. I have no other comments. Overall a well made product that fits well. Kudos to @houstoncarenthusiast for the awesome pics Cheers!! Attached Images __________________ IG: @FLEXSPEC
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06-11-2023, 02:54 PM	#12
airkenny New Member 0 Rep 19 Posts Drives: 18' F80 ZCP Grigio Telesto Join Date: Feb 2017 Location: somewhere on East Coast iTrader: (1)	I've had these for over 4 years now and noticed quite a few led lights have died. Any idea if there's replacement leds available? would hate to have to buy a whole new diffuser.
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