[salguod]

So, while poking around under the hood trying to see if I can fix my AC line, I noticed that after I turn my Outlook off, I get this high pitched, vaguely electronic sound followed by a clunk, then it repeats. Sort of 'Wheeeeeeeeeeeeee-katchunk Wheeeeeeeeeeeeee-katchunk'. It sounds like it's coming from up under the base of the windshield, at the firewall. I don't see an obvious source, though.

I also seem to hear the high pitched sound while the engine's running too.

Is this normal and I've just not noticed it before?

 

[BigTallV]

Not sure if you're just hearing the various things coming to a rest state. Is the 'kachunk' similar to the ABS test you hear when you first pull away from your driveway and start getting up to speed? I hear that everytime I shut off my Outlook and it's normal.

The Wheeeeeee electronic sound, on mine I hear a similar sound, much alike what a leaking capacitor sounds like on some consumer electronics devices (like a TV set). That high pitched (yet faint) sound is normally lasting for a little while after shutting off the vehicle too.

 

[salguod]

Yeah, that's what I was thinking, stuff shutting down. Since I've got this early AC failure, it's got me paranoid about sounds that seem odd and I don't remember hearing this before.

 

[XRDreamliner]

Origin of Noise @ Shutdown - Transmission Solenoids

Normal noise... per GM Techlink:

Transmission Noise
By techeditor on April 1, 2007 7:34 PM

The owner of a 2007 GMC Acadia or 2007 Saturn Outlook may hear a high pitched buzz or whine noise after the engine is shut off. This buzz or whine noise is coming from the solenoids in the transmission. These solenoids will stay active during the TCM shut down, which will last about ten seconds.

DO NOT make any attempts to repair this concern. This is a normal characteristic of this vehicle.

- Thanks to Ron Erman

http://www.sandyblogs.com/cgi-bin/mt/mt-search.cgi?search=.&IncludeBlogs=3,6,7,10,11,12,14,23,28,29&limit=8&page=393

Be aware, that while this note is for 2007's, the 6T75 transmission design has not changed significantly through MY2012, so this note applies to all Lambda years.

 

[6Sixathome]

Same here, normal sounds.

 

[salguod]

Good, that's reassuring.