All,

Since purchasing my 2005 TL I have been without cruise control while driving with the headlights or parking lights on. I attributed this to a short in the tail light/brake light or in the cruise control system itself.

This weekend, I pulled apart my rear end:
https://acurazine.com/forums/showthread.php?t=716996,
took apart both tail light LED boards and found this:




My apologies for the large photo. That tiny nick (from wire chafing over the years?) in the red wire on the inside side of the LED board was allowing it to short on the plastic board. Obviously this wasn't enough resistance to disable the brakelight, but enough to trick the cruise control system into thinking it was receiving brake light feedback.

A little heat shrink and some electrical tape and we're off to the races.

Good luck to anyone else experiencing this problem.

Cheers!