girvan

Here's how to use the additional lights you already have installed but are disconnected!

These models use only four of the six 21W brake lights present. (I was curious as there are 6 dual filament bulbs and 6 "running lights" on the GS300/400, also several other Lexus models use 6 brake lights.)

There are two brake lights in the main rear clusters, however only the lower is connected. The upper one is wired into the trunk where the wire comes to a dead end about 2 inches inside the car!

I bridged this to the active brake light wire using Scotch snap on connectors, one at each side of the trunk and re-taped the black tape on the loom. Unfortunately I did this 3 years ago and do not have a note of the color codes. One thing I do remember is that the color codes have NO relationship to those in the wiring manual as this cable is part of the light fixture which has no color code correlation the the rest of the car! The looms can be found immediately behind the rear lights where the wiring enters the car trunk via a rubber grommet.

A minor downside is the brake light failure detection is still calibrated to warn for 3 or less filaments, so there will need to be 3 of the 6 filaments out for it warn. I had intended to bridge the resistor in the warning sensor to recalibrate it but life is too short...

Sorry I cannot be any more specific because it was a while ago, but if you need to ask you probably shouldn't be thinking of doing this.

The end result is brighter brake lights, which in my opinion tend to keep people a little further back and a more symmetrical look and probably the look the lights were designed for. I suspect the lights were found to be too bright for US DOT specs (the same specs that force much US car lighting to 3rd world status)