Grounds ran to frame, swapped RCA cables, etc. Still noisy.

[Forcefed2002]

Have you tried grounding the outside ring of your RCA cables? Internal fault in the head unit can cause noise that's fixed simply by doing that.
I'm super busy working today so perhaps someone can post pics or tutorial of what I mean sooner.

That technique cured similar issues in my last vehicle.

https://goo.gl/images/YgeJn9

https://goo.gl/images/W2B4oJ

Couple different ways to do it.

If you can pull back the plasticker terminal on that set of cables & solder directly to the "ground" wire, that would be preferable.

 

[BOOMINGRANDPA 5,000+ posts]

Thanks.
Yes, this is where I'm at now. The dash is apart and the RCAs are ran from the head unit and draped over the seats running to the amp.

Something else that occurred to me is that my power wires are running through a firewall grommet that it also shares with the truck's primary wiring harness. I'm wondering if perhaps there's some EMF or something induced into that primary harness. That might explain why getting my 12V directly from the battery cures some of my noise.

yeah like papermaker said see if u can add short ground to hu..

 

[hispls 5,000+ posts]

I haven't tried that specifically, but I know what you mean.
I did measure resistance, though. The grounds of each RCA jack measured .5 ohms or less to the cage of the head unit.

On Crutchfield's advice, I also trying grounding the cage separately to the dash with no luck.

The only thing that's worked so far is running accessory power directly to the battery. I hope to install noise filters on both 12v inputs later today. If that works, I probably won't use it as a long term solution. Instead, I'll probably install another fuse panel and run power directly to the head unit for constant power and via a relay for switched power. At that point, the only connections to the factory harness would be the antenna, back up camera, the reverse signal for said back up camera and CANBUS signals used by the PAC RadioPro (included with dash kit).

At that point I'd say that my problem is under the hood. Since my truck is still under warranty, I've already spoken with the local dealer about investigating "dirty" power. Predictably they said they couldn't help since I'd installed the stereo and therefore might have caused the problem. I'd need a very convincing case to demonstrate otherwise.

The only "under the hood" stuff likely to cause noise is failing battery/alternator or from what I've heard a bum spark plug can cause noise though I haven't experienced that.

 

[longbedbob]

I've already tried about 4 grounds before running directly to the frame. Each time was a new solder/lead/heat shrink combo.

I think that I should probably have mentioned that the new F150s are aluminum body, which is why I finally went to the frame for ground. Resistance from the negative battery terminal to each of my ground frames is a few miliohms.

 

[longbedbob]

The only "under the hood" stuff likely to cause noise is failing battery/alternator or from what I've heard a bum spark plug can cause noise though I haven't experienced that.

There's also a battery management system (load shedding) and a voltage quality module, I believe.

The old adage about an open above or a short below could also be in play. There's a cubic butt ton of modules, lights and accessories that get power when the key is moved to the accessory position. But everything seems to work.

That being said, the truck sat on the lot for about 9 months prior to me buying it, having only 50 miles on the clock when I took delivery. So, it's safe to say that the battery went flat a few times. Although the alternator charges at 14V, the battery never seems to read above 12.4V when I check it a few hours after being driven. So, a dying battery occurred to me. It's currently on a desulfating battery charger.

 

[los33]

There's also a battery management system (load shedding) and a voltage quality module, I believe.
The old adage about an open above or a short below could also be in play. There's a cubic butt ton of modules, lights and accessories that get power when the key is moved to the accessory position. But everything seems to work.

That being said, the truck sat on the lot for about 9 months prior to me buying it, having only 50 miles on the clock when I took delivery. So, it's safe to say that the battery went flat a few times. Although the alternator charges at 14V, the battery never seems to read above 12.4V when I check it a few hours after being driven. So, a dying battery occurred to me. It's currently on a desulfating battery charger.

The alternator will charge at 14v if the battery wont hold a charge, the temp system on those fords will lower voltage to 13.3-13.5 once battery is near complete charge.
The aluminum bodys usually have lots of paint so sanding is needing for all grounds to the frame.

Also if you have a ground loop it is most likely the oem engine grounds that are getting noise, so a simple swap to a better cable with thicker jacket would help.

Pretty much a big 3 is needed.

You can always clear the static by creating your own 12v switched relay setup that will isolate it from the stock system.

Sent from my Moto G4 using Tapatalk

 

[longbedbob]

OK, folks.

I am clearly fighting more than one problem.

Connecting a relay for accessory power and wiring my constant voltage direct to the battery has cured my static ills. Curiously, a noise filter on the accessory supply solved it as well.

However, I still have alternator whine.

Both the amp and the head unit are grounded directly to the frame. As if now, both the head unit and amp are receiving power directly from the battery. There should be no difference in potential.

Here's what I've tried:

1. Removed all RCA inputs from the amp. No whine.

2. Removed JL Audio 4 channel, twisted pair RCAs from the deck, ran directly across the center of the truck - *whine* So it would seem that I have induced whine across the RCA cables when they are removed from the head unit.

3. However, when I try out my shielded pair of cables.... removed from the head unit but connected at the amp - no whine.

4. When those same shielded cables are connected to both the head unit and the amp - *whine*.

5. Ipod connected directly to the amp - no whine.

What next?

 

[los33]

OK, folks.
I am clearly fighting more than one problem.

Connecting a relay for accessory power and wiring my constant voltage direct to the battery has cured my static ills. Curiously, a noise filter on the accessory supply solved it as well.

However, I still have alternator whine.

Both the amp and the head unit are grounded directly to the frame. As if now, both the head unit and amp are receiving power directly from the battery. There should be no difference in potential.

Here's what I've tried:

1. Removed all RCA inputs from the amp. No whine.

2. Removed JL Audio 4 channel, twisted pair RCAs from the deck, ran directly across the center of the truck - *whine* So it would seem that I have induced whine across the RCA cables when they are removed from the head unit.

3. However, when I try out my shielded pair of cables.... removed from the head unit but connected at the amp - no whine.

4. When those same shielded cables are connected to both the head unit and the amp - *whine*.

5. Ipod connected directly to the amp - no whine.

What next?

Again this is a ground loop.
Sand down the ground spots very very good, also take a photo of your *new* grounds as you maybe confusing grounding to the cab sheet metal to the actual frame which would require cutting and going straight to the frame.

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[longbedbob]

Again this is a ground loop.
Sand down the ground spots very very good, also take a photo of your *new* grounds as you maybe confusing grounding to the cab sheet metal to the actual frame which would require cutting and going straight to the frame.

Sent from my Moto G4 using Tapatalk

Aha!!!

So, I'm think to myself, "Bob, go out and take a picture for these folks and show them just how good your grounds are."

While I was out there, I proceeded to check one last thing...

By flashlight, I returned the amp ground to where I had it previously inside the cab.

I reconnected the new head unit ground back to the factory wiring harness.

You know what??? Success. No more whine.

I had static and whine previously at these locations....that is, until I relocated the power source this afternoon.

Anyway, good suggestions, folks. But in heaven's name, why did fixing "dirty" power and returning my grounds to previous "bad" locations fix the problem?

 

[los33]

Aha!!!
So, I'm think to myself, "Bob, go out and take a picture for these folks and should them just how good your grounds are."

While I was out there, I proceeded to check one last thing...

By flashlight, I returned the amp ground to where I had it previously inside the cab.

I reconnected the new head unit ground to the factory wiring harness.

You know what??? Success. No more whine.

I had static and whine previously at these locations....that is, until I relocated the power source this afternoon.

Anyway, good suggestions, folks. But in heaven's name, why did fixing "dirty" power and returning my grounds to previous "bad" locations fix the problem?

A perfect power loop allows for the electricity to ground out correctly.
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[Forcefed2002]

Or it wasn't a ground problem...mmhmm //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[longbedbob]

Or it wasn't a ground problem...mmhmm //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

I've been working on this issue for a couple of weeks now, gradually upgrading components in an attempt to get it to go away.

After an amp and speaker upgrade to the base factory stereo, I had:

1. Static.

2. Whine.

3. A radio station in the background with the radio off. Seriously.

I focused on grounds, grounds, and more grounds with everything I'd installed. I even bought some top shelf RCA cables and better line out converters, going so far as to connect them directly to the speaker level output at the factory head unit.

After two weeks of no success, I just accepted that the problem was with the factory head unit and/or wiring. Since I'd already torn into it, I knew that I couldn't expect help from the dealership for a warranty issue.

I shelled out some serious coin for a PAC dash kit with harness, and a double DIN head unit.

After the swap last weekend, I was left with the static and whine. The background radio station vanished confirming that at least some of my problems were from the factory set up.

Again, I focused on grounds, grounds and grounds.

Only after I wired the head unit to get power directly from the battery did I make any headway.

But you'd think that a good ground is a good ground and that a solid frame connection would be as good as the factory one, which was noisy in a previous troubleshooting step.

Oh well...score one for Easter egging your way through a problem. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Popwarhomie 5,000+ posts]

Glad you got it sorted out.

 

[longbedbob]

Glad you got it sorted out.

You, me and my wallet. LOL.

 

[Papermaker85 5,000+ posts]

A perfect power loop allows for the electricity to ground out correctly.
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stupid you are, know electrical you do not. shut up you will.