The power 3rd row does a little bit of kinematics in order to fold from flat into a seat. Part of the process involves sliding the bottom cushion longitudinally (along the rails). When it got to this point in the process, it made a fairly terrible grinding noise.
After spending at least 45 minutes adding waaaaaay too much white lithium to the tracks, I decided to see if the Cadillac forums had seen this before.
I found this post:
http://www.cadillacforums.com/forums/ca ... st12525057
There's a motor that rotates two cables, which turn worm gears on either end of the track, which turns a gear which spins a shaft. That shaft threading in and out is what moves the seat forward and back as part of its motion. This guy said his cables were actually the issue. I put my hand on the cables when the noise was happening and sure enough, you could really feel it vibrating. I guess the grease dried up.
I didn't take any pictures, but what you essentially do is unbolt the motor (pull the seat upholstery up to get at the two bolts). Once the motor is unbolted (two 8mm bolts), you can use a T-30 torx bit to remove the cable sheath from the motor on either side. The motor is a Bosch by the way.
Once the cables are unbolted from the motor, you simply pull the inner cable out of the sheath (like an old bicycle speedometer). I put some white lithium into a syringe and tried to squirt some into the empty cable sheaths but I think what really matters is lubing up the cables themselves. I did that and twisted them as I inserted them to spread the grease out.
Reassemble and the noise is totally gone. I believe the design flaw here is that the cable is actually wrapped, compressed wire, so it has a pitch as it rotates. I think it essentially pumps the grease out of the sheath over time, because I did see some grease at the end of both sheaths but halfway down the cable was pretty dry.
One POS problem fixed.