Ground Loop Resolution

[S0CAL]

I redid my entire audio system and it was working stellar until my 2 year old Kenwood head unit crapped out last week and I replaced it with this new Kenwood. Now that I swapped my HU out, I have a nasty ground loop. This was surprising, as I reconnected (re-soldered) the harness, and other than the length of some of the extensions (USB, rear/front camera video-in pigtails), all the connections are the same.

I started chasing the buzz. I did notice I initially ran the remote power connection wire in parallel with my RCAs along the passenger side, back to my amp (dummy move). I re-ran it, and the buzz did lessen, but it is still there. I also noticed the aftermarket rear camera video RCA dropped much of the loop when disconnected (this little guy was flaking out on me anyway, so I plan to replace). I have since left it disconnected, and removed it from the switched power, too.

Even with the amp/sub not powered on (disconnected remote power wire), and running only speaker line-in to the dashspeakers, there is some buzz, albeit faint.

Having said all this, is it possible that the new HU has greater resistance than its predecessor? Do I need to ground it to the chassis and not rely on the ground wire currently in play between the harnesses?

I am pulling my beard hair out here chasing this down.

Thanks!

 

[barr0208]

I would try grounding the chassis it wont hurt and may eliminate the buzzing.

 

[BadHabit2Break]

I would ground it also. You can either "T" it at the ground connection in the harness and ground it to metal behind the dash, or ground the chassis to metal behind the dash.

 

[KCaudill]

Have you tried one of these? I had same problem and tried this. All is silent now

https://www.crutchfield.com/p_127SN...a&awnw=g&awcr=47623509025&awdv=c&awug=9008704

 

[S0CAL]

Have you tried one of these? I had same problem and tried this. All is silent now

https://www.crutchfield.com/p_127SN...a&awnw=g&awcr=47623509025&awdv=c&awug=9008704

Wow how did I miss this on their site. Thanks for this, and even if it doesn't work, I am only out $10!

 

[S0CAL]

I think I am going to move the amp's ground to the bench seat bolt and use a big ring terminal. I think there is some ground potential with where I currently have it, which is using triple self-tapping screws into the floor.

 

[IRSmart]

Have you tried one of these? I had same problem and tried this. All is silent now

https://www.crutchfield.com/p_127SN...a&awnw=g&awcr=47623509025&awdv=c&awug=9008704

plus one for this solution. i had a nasty one in my mustang and all i installed was a new HU. threw a ground loop isolater on and all was well in the kingdom.

 

[S0CAL]

any pair or all preamps?

 

[adrianp89]

Ok lets look at this step by step.

1. Was there ground noise before? If not then the issue 98% lies with the new unit/install. I would start with cutting all solder joints and using just crimp caps. Solder can sometimes create serious headaches with one cold solder, and really provides zero benefit over a crimp cap (unless using data wires).

If that doesn't work, then try swapping the amp to see if you still get it. I don't know what happened to the old head unit but it may have taken the amp out with it.

Lastly, I would try a new head unit.

If the issue wasn't there before, no reason to touch anything wiring wise by the amp.

If the issue was there before, let us know and we can take it from there.

 

[S0CAL]

The loop was definitely not there before installing the new head unit. I worked with Crutchfield on Saturday and ended up ordering a new harness adapter, isolating one of the issues I originally experienced (reverse signal wire and parking brake sensor wire signaling weren’t seen by head unit).

The buzzing sound can be almost eliminated if I connect the ground wire from the head unit to the old backup camera video and power cable run (I clipped both ends of this wire but it is still resident in a separate but parallel run of loom from rear bumper, along driver side, all the wall to firewall and into the cab). I found that it worked as I was in the process of running a ground wire to the amp’s ground to the head unit’s ground wire (which did nothing itself to kill the buzz). Since it worked, I left it like that, and thought I was done. I put the HU back, tucking everything away. It sounded really good... until I plugged in my iPhone. The iPhone connects via a USB lightning cable. If I remove the usb from my phone, the buzz goes away.

So, I am back to square 1. Next weekend, I will cut out all my solder connections and crimp everything and go from there. Seriously bummed out.

 

[adrianp89]

The harness issue definitely sounds like that could be caused by a cold solder. (Not to knock your soldering skills).

If the old camera wire is still grounded, un ground that. It may be causing some issues. Actually I would just rip the whole thing out.

 

[S0CAL]

The harness issue definitely sounds like that could be caused by a cold solder. (Not to knock your soldering skills).

If the old camera wire is still grounded, un ground that. It may be causing some issues. Actually I would just rip the whole thing out.

Yeah, I plan to yank it all out and clean it up. No ego issues on my soldering, I just want the buzz to stop. So butt connectors is my next move, next weekend!

Thanks guys.

 

[BadHabit2Break]

did you try grounding the new HU to metal?

 

[WilliamS]

I would start by disconnecting anything not required like the cameras, antenna, and usb ports. If the noise still exists, start with the ground wire for the head unit make sure its not leading elsewhere in the harness. Ive had hundreds of harnesses not match up to the cars wiring over the years. Pull the ground from the headunit side of the harness and ground it to the frame behind the headunit. Thats where I would start, but thats me.