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2006 'servo sound' after braking.

B

BBC0

Full Member
Joined
Jun 5, 2013
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33
At slow speeds, say in a parking lot, when I let the brakes off I can hear the sound of a servo or something running for a few seconds.  The sound is coming from the drivers side front of the engine compartment and is repeatable.  Under the hood I can see a beer can sized item which is part of the braking system and has wires going to it.  I am not sure what this is or if the sound I am hearing is problematic at all.  The brakes work fine.  I have owned my Avalanche for about a year but only recently noticed the sound after lending the vehicle to a friend who turned off the radio!
I would appreciate any insight into this.
Thanks,
Barry
 
I believe your talking about your master cylinder.. I've never noticed a sound coming from my 02 that... but then again i've never really listened hard to it.. If it bothers you get it checked out.. Do you have a friend or maybe a have a friend of a friend?
 
Thanks I know the normal components of the braking system, master cyl etc., but not this piece.  The part that I am reffering to stands vertically on top of another part that has brake lines coming and going to it. It's painted black.  I am guessing that it is something to do with ABS or stability control, but not sure. 
The sound that I hear is like a slow electric drill, just before the battery gives out. 
 
on 2006 you use the Power Steering pump as the Power assist in  lieu of old school vacuum.

 
Here are some pictures of the thing I am trying to identify and which I believe may be making the sound that I am hearing.
 

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and another....
 

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Does anyone know what the heck that is in the picture
 
FIrst is it STOCK or MOD?

IT has wires going into it and looks like an electric motor.
Is it some sort of Comrpessor pump?
Or hydraulic pump/motor set up
 
Don't believe either of our AVs (02/03) have anything like that...
 
In the first pic it looks like it has a readable sticker on it. Can OP get the #'s off it so maybe we can or he can google them or cross reference in Rock Auto?
 
Here is a picture showing the number on the item in question.  I think it is: R00990395  Not sure where to go to research this.
 

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This picture shows that the big hose from the master cylinder reservoir connects into this part. As far as I know, this is a stock item.  This Avalanche seems to have just about every option available.
Thanks for all the interest.
 

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your master cylinder picture is hard to see as the sun washed it out.

Re-take please and show where this hose goes into the part in question...
I see the 2 big RED & Black WIres?
 
Question BBC0 do you live in the US. ?
 
It's not in the service manual also.
 
My Avalanche is a Canadian vehicle.
Here is a pic of
a) the master cyl. reservoir hose connection
b) same thing from above
c) the other end of the same hose connecting to this unknown device.
I notice now that there are no vacuum connections to the power brake system.
 

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Are you the original owner. I pretty sure I know what it is.
 
As mentioned earlier, this is a 2006 that I purchased less than a year ago. 
 
Well it sucks brake fluid from reservoir thru the hose.
Then pumps it out under pressure thru that single line to something.

Follow that metal line to where ever it goes...

 
I think it's a PTO (power take off) for a snow plow.
 
BBC0 said:
My Avalanche is a Canadian vehicle.
Here is a pic of
a) the master cyl. reservoir hose connection
b) same thing from above
c) the other end of the same hose connecting to this unknown device.
I notice now that there are no vacuum connections to the power brake system.
Click to expand...








I can see the accumulator now in the pic. Snow plow PTO part. Good call.
 
I looked and the only line leaving this device is going to what looks like a 3 way valve with a blue marker on it.  The lines exiting this valve go up to a thing attached to the end of the brake master cylinder where the big vacuum thing usually is.  There are no other lines taking of for any other extra, and I doubt that there would be enough volume in the reservoir to drive anything else but a sealed hydraulic system like brakes.
I have taken more pictures but its hard to get room for decent shots.
1) 3 way valve ?
2) 2 exit lines from 3 way valve to deal on the end of master cyl
3) 3 way valve from above
4) Reservoir
5) Reservoir from drivers side
6) as above different angle.
 

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