Image by Greg Banek

OUTER LED RE-WIRE GUIDE FOR RETROFIT BMW OEM LED TAIL LIGHTS

For BMW M3 (E46) models 2001 - 2003.5
by TigerDave

For models 2003.5 - Present that came from the factory with LED tail lights, please check out this guide instead.

Kudos goes out to hotcello and peterlai for discovering this!

 

DISCLAIMER:

This DIY guide is only for informational purpose and the author or the website owner is not responsible for any malfunctions, damages, property loss, injuries or accidents or liabilities of any kind. Proceed at your own risk. There. Now with that said...

DETAILS

In the middle of the 2003 model year, BMW switched from the tail lights on the M3 from regular incandescent bulbs to tail lights that contain LEDs. These newer style lights are brighter, never burn out and just plain look cool. The best part is that if your M3 lacks the LED-style tail lights, you can buy and install them yourself!

The LED tail light itself is broken down into 3 parts, the top portion which flashes yellow (turn signal or hazards), the red bottom portion which glows faintly when the parking or headlights are on but intensely when brakes are applied, and a red outer ring of LEDs around the bottom portion which also glow faintly when the parking or headlights are on but intensely when the brakes are applied hard. This is known as "Adaptive Braking". Since the older model M3's came with non-LED tail lights they do not have adaptive braking, and therefore the outer LEDs always glow dimly, even if brakes are applied.

If you have an M3 that is 2001 - 2003, you can purchase and install the new LED tail lights, however, the outer ring of LEDs will always remain dim, even if brakes are applied because such models lack the adaptive braking feature.

PLEASE NOTE

Even after you swap out your non-LED tail lights with the LED ones, you may need to take your M3 to the dealer and have your Light Control Module (LCM -- the box that houses your headlight control switch) reprogrammed to get rid off the "Tail Light out" warning lights on your dash (shown on right).


However, some people (including myself) noticed that although the warning lights DID appear after I connected the unmodified adapter cables, they went away after doing this re-wire mod!


Also, M3s with a production date prior to 09/2001 will need a new LCM altogether.


This how-to guide will show you how to rewire the BMW wire adapters so that the outer LEDs will also light up intensely any time the brakes are applied.


Tools you will need:

  • 2 Quick Connects that work with 22-gauge wire

  • Pair of pliers

  • Electrical tape (optional)

DIRECTIONS
(REFER TO PHOTOS BELOW)

First of all, the new LED tail lights will come with a pair of wire adapter cables. They are labeled LEFT and RIGHT.

If you wish, you can remove the cover on the end that plugs into the tail lights so you can familiarize yourself with the insides, but it's not required for this mod.

To remove the cover, simply insert a jewelers or a small flat head screwdriver under the raised area shown in the photo on the right. Twist the screwdriver slightly to raise the cover and then slide the cover off.
    
You will notice that slots 1 and 8 are labeled and that slot #4 is empty. This is the slot that triggers the outer LEDs to glow intensely when power is sent to it.     


On the large end of the adapter cable, carefully remove some of the electrical tape. Enough to expose about 2 inches of wires is sufficient.     


Trim off the excess electrical tape and locate the black wire with the green stripe. This is the wire that supplies power to the cluster of LEDs when the brakes are applied. We are going to tap into this wire and send power to slot #4 also.     


You will need a pair of "Quick Connects". You can find them anywhere. I found a 4-pack at the local Wal-Mart for $1.17.

Try to purchase the smaller Quick Connects that work with 22-gauge wires.

If you have never worked with these, then you're in for a treat. Quick Connects allow you to splice into an existing wire and also send the electrical signal to another wire. No cutting, soldering, or taping is needed. Just a pair of pliers.
    
Slide the Quick Connect over the Black/Green wire and then slip in the new wire you wish to also send power to.

Side note: Although it's not required, I recommend that you purchase an extra pair of adapter cables like I did (~$20 US) so that you have the proper connector that slips into slot #4. You can also try to locate those connectors yourself, but don't bother trying Radio Shack. Because they don't carry them.

If you would like to purchase a pair of wires that have the correct connector, just contact me directly and we'll see what we can do.
    
Once both wires are in place, use your pliers to crimp the metal portion into the Quick Connect. If done properly, the metal part will bite into both wires piercing the outer jacket and coming in contact with the actual copper wire inside.

Snap the Quick Connect closed.
    
Slide the other end into Slot #4.

Side note: Although it's not required, I recommend that you purchase an extra pair of adapter cables like I did (~$20 US) so that you have the proper connector that slips into slot #4. You can also try to locate those connectors yourself, but don't bother trying Radio Shack. Because they don't carry them.

If you would like to purchase a pair of wires that have the correct connector, just contact me directly and we'll see what we can do.
    
With the new wire securely inserted into slot #4, slide the cover back on (if you removed it), wrap electrical tape around it so it doesn't hang loose from the rest of the wires, and install!

Once installed, turn your key to position #2 and have a friend press and release the brake pedal. The outer LEDs should glow intensely when the brakes are applied.

Don't forget to take your M3 to the dealer to replace or reprogram your LCM to turn off the tail light warning lights on your dash -- if you get them. I didn't!