Vansibel

It's been going on for almost two year now and I finally decided to post a video. When the car is started for the first time during the day after 25 second (doesn't matter if I'm in park idling or moving in reverse - parking brake are not engaged and gas engine is usually running) there is an audible squeal coming from what seems to be (but not 100% sure) the middle/back of the car (as shown in the 20 seconds mark near the end of the included video). I just noticed in the video there also a small high pitch noise at the very start. This usually don't happen again during the following starts during the day. It's as if an actuator or other mechanical part was shutting down after the car sit for a while and then reopen when the car is started. Could be wrong but I get the impression that if I manage to find the part a small amount of grease would fix this. I know that there seems to be an actuator/switch on the ls600hl exhaust that sometime get faulty (hydrocarbon switch) by getting stuck in place. Maybe this is what is rubbing when it's opening, I have no idea.
Thanks for the help
Edit: seems to be doing it more than once a day when the car is started and not only the first time

rmawyer

Air suspension issue? Assume it's not your belts or pulley bearings?

Vansibel

Air shocks don't seems to be the issue as the noise won't happen when adjusting the suspension height. I'm pretty sure the belt is not the culprit as the sound don't seems to come from the engine bay and does not sound like a worn belt.

Vansibel

Small follow up if it can help a fellow member. I ended up having the dreaded P1083 code which relate to the hydrocarbon switch being stuck and after that the sound stopped. Got under the car and sprayed some non flammable rust penetrant oil through the aluminum shield space of the actuator without dropping the exhaust. Cleared the code and waited half an hour. That actually got the actuator unstuck and saved me a 8k dealer visit. My recommendation would be not to wait when the problem occur in order for them not to have the time to get stuck really good or even lubricate them as a preventive measure preferably with non flammable and heat resistant grease.