Hey everyone,

First time poster here. After spending over a week on this forum troubleshooting, reading threads, and trying every suggestion I could find, I finally solved the white noise / hiss / static issue that happens when pairing an aftermarket head unit with the PAC RP5-GM11 in a C6 Corvette. Since there wasn’t a clear answer out there, I want to document exactly what worked so others don’t go through the same frustration.

The Problem:

After installing my Kenwood DMX5710s CarPlay deck with the PAC RP5-GM11 (into the factory Bose system), I was getting constant white noise/hiss/static through the speakers — even at 0 volume. Music still played fine, but the background noise was always there. The only way to get it to stop was to "mute" the stereo. The root cause is that the factory Bose amplifier does not like receiving high-level (speaker-level) inputs from the head unit. The PAC harness, by default, is wired this way, and it overdrives the amp’s input.

Troubleshooting I Tried:

• Checked and re-did grounds.
  
• Added an extra ground — no effect.
  
• Verified battery health/voltage and even swapped in a new battery.
  
• Carefully checked wiring and harness connections, completely rewired the harness.
  
• Crutchfield sent me a replacement PAC unit (great support, by the way), but the noise was still there.
  

Nothing fixed the issue.

What PAC Told Me:

When I contacted PAC support, they confirmed this exact issue: the Bose amp (and other factory amps) won’t behave well if you feed them high-level inputs. They suggested turning down the gain dial on the interface. This had no effect. They suggested two options:

1. Use a Line Output Converter (LOC).
   
2. Or bypass the high-level inputs completely and run RCA cables from the head unit’s pre-outs into the PAC.
   

The Fix (What Finally Worked):

• Ran RCA cables from the Kenwood’s pre-outs directly into the PAC.
  
• Made sure to use the amplified audio port on the PAC interface (all C6 Corvettes have a factory amp, Bose or not).
  
• Reinstalled the head unit and performed an “Initialize” (factory reset) on the Kenwood deck.
  

Result:

• The hiss/static is completely gone.
  
• The volume control is fixed — it used to be way too loud at “10,” but now the levels are normal and progressive.
  
• System sounds clean and works as it should.
  

Takeaway:

If you’re installing an aftermarket stereo (Kenwood, Pioneer, Alpine, etc.) with the PAC RP5-GM11 in a C6 Corvette and you’re hearing hiss/static at low or zero volume:

• Don’t waste days chasing grounds or swapping PAC modules.
  
• The issue is the factory amp receiving high-level inputs it doesn’t like.
  
• Run RCA pre-outs from your deck into the PAC, use the amplified audio port, and reset the head unit.
  

This worked with my Kenwood DMX5710s, but the fix applies to any other unit experiencing the same problem.


Hopefully this helps the next person searching the forum for answers!

 

The whole point of using the correct interface for your vehicle is so that it will make an aftermarket head unit compatible with your oem sound system. That includes sending a low level signal to the amplifier if you have a factory amp. I have the older Pac RP5-GM11 interface and on the Pac module there are 2 different locations to plug the wiring harness into. One side states for vehicles with factory amp and the other side is for cars with no amp. Are you sure you installed it correctly? All C6's have a factory amp, Bose and non Bose. The Pac RP5-GM11 is made to accommodate mulitiple vehicles and work with cars with and without amps. So if you installed it incorrectly in a car with a factory amp, you would get the static hiss noise that you were referring to. If you installed it properly and it was working properly, you wouldn't have any static.

 

This is a diagram of the newer version of the RP5-GM11. As you can see, it has 2 different ports for connector 3. One is for systems with no factory amp and the other is for amplified audio output. The amplified audio output should put out a low level signal to be compatible with an amplifier. Did you plug the harness into the correct port?

 

Yes, of course I did. I spent a week trouble shooting this issue. When plugged into the "non-amplified" port, the static was much louder. This is my 20th or so stereo install. First time with BOSE / factory amp involved.

This is an ongoing issue. See this thread which helped steer me in the right direction toward RCA's.

https://www.corvetteforum.com/forums...c-noise-2.html

Further, this message from PAC:

Maybe most guys who do the install don't pick up on this issue as its not noticeable when the engine is on.

Cheers

 

Ok, thanks for clarifying. Like I said in my post, the interface is supposed to be designed to send out a low level signal to work with factory amps. If it's not, then it's definitely not functioning properly. With the Pac RP5-GM11, that's why it has 2 different ports for the plug. One is supposed to be a low level output. From your post about your conversation with Pac technical support, it wasn't clear to me exactly what was going on since they didn't seem to acknowledge that the unit is supposed to be able to send out a low level signal. I wasn't aware there was an ongoing issue with the newer Pac units. Thanks for the additional information. Hopefully, between my posts and yours, someone else reading it will have a better understanding going forward. Thanks again.

 

The PAC only comes with 1 white and 1 red male RCA. The Kenwood has 4 ports for it for rear and front left/right. Did you use RCA splitters to achieve this?

 

The RCA cables on the PAC are the RSE (rear seat entertainment) cables used in some vehicles, these aren't used in the Corvette for obvious reasons.

 

You have something hooked up wrong I have Kenwood ddx9907xr and using Bose amp, Been in car for 2/3 yrs. I just added a compact sub which also has amp.
sound is fine low or high

 

I'm having this same issue with my Alpine HU. What RCAs did you hook into the head unit and into the PAC? You don't happen to have any photos of your wiring setup do you?