Accumulator Noise
 

Hi all,

I have a 2011 Silverado Hybrid with just under 50,000 miles on it. As I have posted before this truck has been nearly trouble free but over the last 10,000 miles I have a new noise which makes me a bit nervous. There noise sounds like a grinding/vibration, which is very noticeable at low speeds and while stopping. It is intermittent and seems to be coming from the brake accumulator (my suspension confirmed by the Dealer tech). There are no codes being thrown or any other issues - just a loud noise. The accumulator still seems to make the 'normal' noise at least some of the time - but from time to time it is very loud.

The dealer was going to do some research to see if a TSB or other advisory is out there on this.

Any thoughts?

Re: Accumulator Noise
 

is it like a ticking sound?

Re: Accumulator Noise
 

It's has a higher frequency than a tick - it is more like grinding gears.

Re: Accumulator Noise
 

You can pump the brakes while in Auto-Stop to make the brake pump run. If you do it in a garage a couple of times that can help sort out the pump noise from others.

Re: Accumulator Noise
 

I had the truck go into Limp mode yesterday. Got to the dealer this morning and try found the source of the noise and my traction alarms - bAd thottle body. Turns out the noise was from the TB the trick was to pop the hood and bypass the safety switch - as soon as that was done you could hear the TB grinding away. Accord to GM no warrenty on TB after 2010 - I guess they consider them a wear item. I am out of pocket about 600 bucks- but it should be fixed.

Re: Accumulator Noise
 

under 50k miles, it is a warranty item. go to another dealer.

Re: Accumulator Noise
 

the dealer replaced mine because of the annoying sound but no driveability issues.

Re: Accumulator Noise
 

I looked at a few sites online - GM changed the covered items in 2010 so that Thottle Bodies are no longer covered by the powertrain warranty. They also CLAIM it is not an emissions component - however I am not sure about that under California Law. They vehicle would have failed smog check due to a check engine light. Lucky for me I happen to have a few contacts in the Air Quality World (it's my day job).