I have added an aftermarket stereo to my 2000 disco 2 with Harmon kardon. I purchased the metra amp integration harness and soldered everything for clean connections. Everything went smooth with the exception of a buzzing sound that occurs as soon and the head unit triggers the Harmon amp. I added an additional ground to the head unit, once again soldered the connections with a high quality ring terminal to a ground point near the passenger foot well and it seemed to make the problem worse. I am trying to avoid ground loop add ons as they seem to mask the problem. I have also noticed that if I disconnect the rca from the head unit, it does not change the issue. Any other connections I should check?

 

Does the buzzing noise pitch follow your engines RPM?

 

It doesn't. The buzz can be heard even if the truck is in the acc position.

 

It doesn't sound like a ground loop issue at all then. First thing I would do is check for shorts in your RCA connectors.

Running additional grounds to other parts of the car is a bad Idea, just one good ground wire to your AMP from your Head Unit will all but eliminate ground loop induced noise. It is the potential electrical difference between various chassis ground points that cause ground loops in the first place.

 

Got it. I will run the ground to the amp just to see. Where is the Harman amp located?

 

It is under the drivers seat. Not to difficult to access.

 

Thanks for the help!

 

Difficult one. Possibly a potential between the HK amp and the new head or no ground or bad ground at the HK amp. Could even be interference from the alternator which isn't uncommon.

 

RUN THICK ground wire to ALL components.
One from the other.

May be a ground loop issue.
You need to run a thick wire from the grounding screw on each component to the other.

Also - if you are using an inverter or power convertor, that may be the buzz too.
You may be hearing switching power transistors.

you may want to try capacitors from ground to the power feed on each piece of equipment too.

 

Ran a ground from the deck to the ground on the amp and no dice. I don't really get these things. My 88 RX7 anything metal is a good ground.