I've got a ground loop between my new head unit and the stock amplifier in my ES300. I've re-grounded both the stereo's adapater and the stock amp's adapter, to a common point and i still get the noise. I was told by one person to try to ground the actual metal cage my stereo is in, i dont know..

the Lexus schematics show the ground on the harness encircling all the other wires and it says it's shielded. i suppose the Nakamichi doesn't have this same setup, as its illustrated as just for the Pioneer stereo.

So, does that mean the ground is connected to the rest of the wires' shielding? the wires are simple ones, just copper strand in a sheath. i don't see shielding in anything aside from the RCAs..

What have other people on here done to balance a new head unit with their Lexus system? I see lots of people with issues but no-one ever posts what fixed their problem. Either they dont find the answer or don't bother to tell the world.. a shame

 

I'll reply to myself, because I made some progress. It seems like attaching an additional ground wire (it has a normal ground and now an addt'l ground wire, to the same bolt near the wheel well) to the metal sled of the stereo helps, but I still get engine whine. it seems like it cuts the problem in half. so, do I:

a) run long wires to the battery negative for the head unit and the amp? (already have a hole in the firewall)

-or-

b) add a thick gauge connection from the battery to the chassis?

expert advice, anyone?

 

 

I have always had success with choice A. Whenever you ground your electronics to the body, the system becomes susceptible to any currents flowing in the body metal (ground). These currents can induce local voltages that disturb the nature of the ground, producing noise.
You can usually get away with grounding an amp to the body, since the currents are high. But the headunit is more sensitive, so a direct battery connection is better. Create a single point ground and ground any other electronics to the same ground.