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Discussion Starter #1
Hey folks,

Bought my '08 9-3 Aero SS just a couple of months ago, and it has always made a strange, whirring sound, repeating every second or two, when the key is turned to on, even before I've started up the engine. It sounds like a cell phone that's set to vibrate is somewhere behind my dash, here's a video (might need to turn the sound up to hear it). It will just keep doing that until I turn the car off - I think it does it with the engine on, too, just harder to hear. If I press on the brake, seems to change the duration of the sound.

Any thoughts on what it might be? I thought maybe ABS module, but i'm not getting any strange indicators on the dash (nor CEL), and the sound doesn't seem to come from there with the hood open, seems to be somewhere in the front passenger side of the engine bay. Also, I just replaced the ABS pump (pump & valves only, not the electronic module) a couple of weeks ago, and it made no difference.

I didn't care much about it until last night when I had the key in the on position (but engine off) for about 10 minutes or so playing with a new radio I'd installed, and it ran my battery dead.
 

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Couldn't hear it even with my laptop volume all the way up. Could it be the HVAC fan? Turn off the ACC (turn fan speed control fully counterclockwise) and see if sound goes away.

(If radio kills your battery in 10 mins you may need a new one.)
 

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By what you are saying, it is the brake vacuum pump. Located PS wheel well, front of tire.
You can disconnect the connection on the vacuum sensor, this should turn off the vacuum pump.
The sensor is located right by the RH side strut mount, as seen in this thread.


If the sound stops after removing the connection, you have a leak in one of the hard lines for the brake booster. Pretty common

link for the parts diagram, to give you a better idea of what you are looking for.


good luck
 

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Discussion Starter #6
so, based on the video I posted, I diagnosed my problem to be a leak in the vacuum hose that has the T connection and runs to the engine (this part) . I replaced it, and unfortunately the vacuum pump is still coming on repeatedly (though I think less often than before?) any other ideas where the leak might be? If I bypass the T connector and connect the other two hoses directly, the line holds vacuum (no pumping after a bit).

Somewhat unrelated, while I was in there replacing the hose, I removed the MAP sensor that was in the way of the hose near the rear of the engine. It looks like it should have a hose connected to the bottom of it, but it didn't. Where would I find the hose that should be connecting into this?
270644

270645
 

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it's the Atmospheric/Barometric sensor..MAP sensor is located in the manifold..
 

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Discussion Starter #8
whoops ?, thank you. I googled the part number and it said MAP sensor, I guess it pulls double duty in other cars. Should definitely have no tube connected to it, then, correct?
 

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Yep, no hose. Sits on bracket held in place with the 10mm bolt.

As for the leak, in the "T" fitting system. One side goes to the intake but has a check valve. I would remove the connection and see if it is sucking air from there, tho i doubt it-worth the time to check it.
The other side goes to the Venturi valve which is connected to the valve cover. The venturi might be cracked or the check valve is stuck open.

Not sure if you download the WIS yet, there is a wealth of information in there.
Good Luck
 

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Discussion Starter #10
you nailed it, Salth. Had the car w/ a Saab mechanic this weekend, he traced the problem to the check valve in the venturi piece being stuck open. New one on order and should be installed in a day or two. Sort of wish I had tried swapping it myself, first, but just glad it's getting fixed, haha. Thanks again.
 

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you nailed it, Salth. Had the car w/ a Saab mechanic this weekend, he traced the problem to the check valve in the venturi piece being stuck open. New one on order and should be installed in a day or two. Sort of wish I had tried swapping it myself, first, but just glad it's getting fixed, haha. Thanks again.
No problem, glad i can help. I had that fail about 6 months ago. Keep in mind, there is a seller on Ebay that has these for about 100. They don't have the correct fitting on the end that connects with the tee. I saw that just prior to ordering it.
As a side note, saw you removed the factory Nav and installing a new radio in another thread. If you are thinking about getting rid of the Factory radio let me know. I can put that to good use.
 
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