HU on without ground??

[Jchan]

I just check the ground for the HU due to whining noise and stumbled into something quite confusing. After I removed the ground lead and see if whining was at the ground but turn out nothing change. However, my HU still can operate while the ground is removed. I just don't know how in the world it still operate without ground. I am really confused and the annoying whining still exist. Any feedback is welcome and appreciated.

[atobe]

well the whole car is ground and the HU's chassis is ground as long as those are touching it's grounded

[Jchan]

I understand what you meant, but the HU outercasing was not touching any part of the chasis and was not grounded. That 's where I wonder why it's still turn on. Maybe I 'll try to use process of elimination.

[touringcamry]

Yeah, the same thing happened in my old car. The radio could be dangling from the dash with the face resting on the shifter with the ground wire disconnected. No metal part of the stereo was touching any metal part on my car.

[cam2Xrunner]

It's grounded by the Antenna.

If you don't listen to radio, try disconnecting it there and give the headunit it's own grounding point. You may also want to ground the chassis to help get rid of noise.

[ID_hauler]

A lot of people forget that the antenna is a ground and of course a potential source of noise, one reason is a ground loop can be formed because of multiple grounds to the HU. I recall somewhere that there are "antenna ground isolators" to eliminate some specific problems.