double din picking up throttle sound

**surkon** · 02-08-2009, 10:38 AM

Hi guys, Im looking for some help with my double din head unit in my 2005 sierra denali. I have installed it myself and have installed many in the past without a hitch. My problem is this, with the unit instaled everything works great but there is a "whistling" sound coming through my speakers. Its picking up my tps sensor I think. The best analogy I can make is that it sounds like an overactive turbo. Lower pitch at low idle but almost sounds like it "spools up" as engine rpm increases. I have an on star adapter box installed in line with the head unit. could that be the problem? any opinions are welcome! If it helps the head unit is a kenwood DDX712 and the onstar unit is called a "GM onstar class II data bus interface"
Thanks!

**FastBlak** · 02-08-2009, 11:13 AM

First thing i would do is re-ground the headunit. Assuming you used the factory ground in the harness. Factory grounds suck

**RichDash** · 02-08-2009, 03:25 PM

sounds like you ran power and signal wires together...

**Exalted512** · 02-08-2009, 04:59 PM

I'm assuming you don't have amps? If re-grounding doesnt work, it is more than likely your harness (if its the one that uses RCAs). If it is the one that uses RCAs, unfortunately theres not a lot you can do besides buying a couple of ground loop isolators...the model number is PAC SNI-1.
-Cody

**surkon** · 02-09-2009, 04:24 PM

Wow, I never would have guessed that a ground would do this. Ill have to give that a shot. I do have the rca connections... but hopefully that ground will do the trick. Just a normal groung wire to the head unit case is good enough?

**Dyabolical** · 02-09-2009, 05:12 PM

Alternator whine.

Reground the head unit, preferably to an actual ground point and not just to sheet metal.

**07blkchevyz71** · 02-09-2009, 06:12 PM

My OBS Sierra did this and I thought it was the harness so I bought some ground loop isolators and they didn't do anything...so I just regrounded it to something a little more stable.