Drive by wire hum???

[Spec_C]

I've been combating engine noise in my system for some time not. I've rerouted all my speaker leads, power wire, changed out rca's and changed my ground to numerous contact(clean) areas, and still have this crazy hum when I put the key to the "ON" position.

I've come to the realization that the hum coincides with the drive by wire sound. With the key in the on position and car off, the hum changes when the throttle is pressed. The only thing that I can think of is that my power wire that goes from the battery to the distribution block (0/1 gauge) may be picking up the excess noise? It's not like alternator whine that changes pitch, it's just a constant hum.

Please, can anyone chime in and help me with this dilemma

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[drmichael]

I have the exact same noise you're describing! Sometimes, if you're lucky enough, and "hold" the gas pedal at a certain position, the noise will go away for a bit..driving me crazy!

[Spec_C]

I've been try to troubleshoot for the better part of today with no luck. I tried following the diagram for noise on the crutchfield site, and have possibly narrowed it down to the noise coming from the power lead/s on the deck itself. Crutchfield recommends getting a noise suppressor for the power leads. I'm not sure if that it'll help but I went through all the steps and this is where I sit at this point unless anyone else has more suggestions.

[Uncanny]

it sounds like you are getting a feedback loop of sorts. This can be caused by a ground loop, where the ground system for the dbw system is running on the same plane as the ground system for the amplifier/source, causing the voltage levels to change as you press the throttle and thereby making things go screwy.

Try the following: Make sure all factory grounds are good and clean. You can update several of them to 4AWG, especially if you are pulling 1/0 from the battery. Same goes for the alternator to battery connection, run a fused 4awg wire straight from the alternator to the battery as well.
Run your 12v sources for the deck straight from the battery/key cylinder. The fuse box is one of the NOISIEST places in a car. Ground the deck to a clean chassis ground behind the radio instead of using the factory ground point (which may be shared with the dbw system).
Also, level the ground plane between the source unit and the deck by running a 16-18 awg wire between the ground of the deck and the ground of the amp. YES, i've seen this one work. You can also try grounding the shields of your RCA's to chassis. Make sure they are run away from all 12v sources in the car.

Noise suppressors and ground loop isolators are a last ditch effort and ALWAYS reduce signal strength/voltage

[ardvark666]

Wow, nicely said Uncanny. I just wanted to add that your power leads might seem like the problem but sometimes it helps to add another battery ground to a different point than the stock location (you can keep one on the stock and add one more). Get a friend to place a nice 8 or 4 ga section on each component and make sure you isolate amps and anything that can be separated. Ground loop issues will make you crazy and sometimes you can only minimize them, but it's usually a stupid fix that does the trick.

[drmichael]

is running a ground wire, from the battery, to a distribution block in the trunk (i know it's a long run..) ever a good idea? would it help?

[Aaron'z 2.5RS]

I'm going to say that 90% noise problems are ground problems...

Much of it Uncanny touched upon...

Doing the "Big 3" can help (search)

Making sure the deck/amp(s) is properly/well grounded, helps

What sort of RCA's are you using? What deck? You know Pioneers are well known for this issue (Pico fuse issue)

The amp(s), how are they mounted? What amp(s)?

[ardvark666]

Don't run a long ground like that. You always want grounds to be as short as possible.

[couchflambeau]

Originally Posted by Uncanny

Also, level the ground plane between the source unit and the deck by running a 16-18 awg wire between the ground of the deck and the ground of the amp. YES, i've seen this one work.

As have I, used to be common practice with the a/d/s amps I used to install. I'd usually use a piece of inexpensive 12 Ga. bulk wire since the runs to the amp grounds are typically longer.

I've heard cases for both sides of the 1/0 return ground wire for the amps... The only case I've heard that makes sense for the use is some cars that might make extensive use of adhesives to bond metal instead of welds, I don't know of any car yet that does that though. Meanwhile, as long as you find a SOLID VERIFIED ground spot, I'd stick to the chassis ground. Seat belt bolts have always worked well for me on imprezas.