Hi All,

First time posting here so be kind

I have used this forum as a reference point for upgrading my sound system in my VY Executive. Please see below for the story so far:

1. Decided to upgrade sound system, without replacing factory head unit. Started by installing new Sony Xplod 6" speakers in the front (used existing wires)
2. Installed new Sony Xplod 6x9's in parcel shelf. Tapped into wires going into the door looms (factory speakers still in doors but not connected)
3. Sound quality was much better but the volume inadequate
4. Installed a Kenwood Amp in boot - mounted upside down so as not to impede on boot space. Ran remote power wire from the "handsfree" accessory wire behind glove box. Power wire runs down drivers side, through firewall and connected to battery (in line fuse connected close to battery). I used 15amp wire for both power wires (purchased at AutoBarn). Ground Wires are connected to chassis underneath rear seats (there was a connecting point already installed for this, ex police inspector car). High line connection used for amp input and bridge mode for speakers out. I used speaker wire purchased at Bunnings (thickest I could get there).

Many of you would consider this a standard and simple upgrade. I have not had any experience doing electrical work on cars and this was my first attempt (as I enjoy doing little projects like this).

Now, everything functions as it should (sounds exactly how I want it to) when the car is turned on (in accessory mode, as in radio on but engine not running). Once I turn the engine on, the speakers begin emitting a bit of a strange, high pitched noise (this doesn't happen unless engine is turned on). Can anyone please advise what might be wrong here?

I initially thought that the Ground Wire connection was inadequate. I checked this connection and ensure that it is fixed to the chassis/connection point.

What else could it be? Could it be the wire type I used?

Any help would be greatly appreciated!

Thanks
Nortorious