Brake Light Mods
Technical Correspondence
Roundel, Dec 1994
by Steve C. Wilson
I have often been tailgated by someone driving an oversized vehicle capable of squishing my prized BMW or worse yet, someone in a car that fits the description " no insurance, no license, no assets, judgement proof." Since I cannot always avoid these situations, the second-best solution would be to give them adequate warning that I am stopping or about to stop.
Unfortunately, the stop lights on my 6-series are not nearly as good as the brakes. Given the value of the car, they are a joke. Our 5-series car has somewhat better stop lights but they also need some major improvement. My solution was to make the European fog lights also function as brake lights. There are two additional high-intensity light positions behind red lenses in the taillight assemblies that are completely unused in the US-version cars. Using these as brake lights will double the illumination that appears when you hit the brake pedal. The following is applicable to the 5-series and 6-series cars. The 3-series and 7-series are probably similar.
For the 5-series cars, purchase two additional bulb sockets as used for the brake lights. Remove the rear trunk liner panel. In the vacant light position, remove the three-pointed plastic tab that blocks this hole. A new 1156 bulb and the new socket can be installed just like the other lights. The six-pronged electrical connector has one vacant spot. Unplug it and slip an uninsulated female spade connector with a short piece of wire attached into the connector plug, oriented identically to the other connectors. It will snap into place. Carefully remove a portion of the insulation from the brake light wire near the connector and solder the added wire to the brake light wire. To complete the installation, tape the connection to restore the insulation, plug the connector plug into the taillight assembly, test the lights and replace the trunk liner.
For the 6-series cars, our Munich designers have given us a more difficult task. The bulb contacts are integral with the plastic housing and seem to be unique to these cars. The vacant position has no contacts and no means of holding a bulb. The contacts are unavailable as parts. I attempted to duplicate the contacts with a metal bulb socket without success. Without giving up, I carefully soldered a wire to the contact point and another wire to the side of a new 1156 bulb, then wrapped the bulb base with electrical tape so that it firmly fits in the hole from the lens side. The hot lead uses a small alligator clip that attaches to the existing brake light contact. The bulb base wire needs to be grounded. It is now somewhat inconvenient to change this bulb, but the added light is well worth the effort, assuming the bulb ever does burn out. While the taillight assembly is apart, check the reflective surfaces. I found black paint overspray on what should have been silver. I am convinced the car came from the factory this way, further worsening the brake light situation. Plastic model paint restored the color. To complete the installation, double-check the wiring, test the lights, reassemble the taillights and replace the trunk lining.
The additional lights have absolutely no detrimental effect. The check panel will not tell you if only one light has burned out. If both lights do fail on one side, the check panel functions as designed. Checking your own stop lights periodically makes good sense anyway. You will now have either four or five stop lights for the person behind you to notice.