umm ... the loss of RCA ground IS the result of the pico fuse blowing, grounding the case of the HU should have the same affect as grounding the 'shield' of the RCA. it is a painfully quick and easy one to check (just pull yourself away from the keyboard (you know you can do it) and go put a jumper on one and connect it to ground) you can connect from the HU area or the amp area whichever is easier... 2 minutes tops to check including the time to put on your shoes and walk to the car

 

I'd say is the RCA.

 

I had an amp make my subs have a nasty hum one time and all i did was wiggle the adjustments for gain and for fz and it went away . Prob not related but thought would throw it out there ne ways

 

awesome!!! I just got home to some time tonight I'll go try that. I've got a battery in the back so first I'll try grounding on the rca shield to the negative post back there and hope for the best. Thanks John

 

I have had this as well, loose connections or a bad solder joint in the amp OR the RCA can cause the dreaded alternator whine. This one tends to cycle as you hit the brakes or take a sharp turn (it only happens on right hand turns for instance) the key is sometimes it isn't there.

a 'regular' ground is usually due to a poor ground connection (or a connection point with an uncommon potential to the other ground points). it's symptoms are it starts with a new piece of equipment being installed and is a whine that changes with engine RPM (engine on).

with the loss of RCA shield ground the symptoms are like the regular ground but there is usually switching noise as you change tracks on a CD. This one can come on with the pico fuse blowing on a Pioneer HU, or come on as a solder joint goes bad (usually with home made or abused RCA's). This one can also come on during a new equipment install.

There can also be a ground induced by a speaker wire getting grounded.

The more insidious grounds are the now its there now it isn't types. My SHO had horrible moisture issues where water would get in the car from the lower windshield seal and silently and invisibly drench electronics

 

Nah, this is a fairly common occurrence - especially with Pioneer decks for whatever reason. It drive you nuts the first time until you find out why an what the cure is, and then you remember it and the symptoms forever.

 

Myles, not sure if you did it yet, but you can just solder a small stripped section of wire to the shield of the rca. then just ground it somewhere. Should solve the problem, and takes less than 5 min.

 

Well I tried grounding the rca shield at the amp to the battery I have back there and it seemed to make it worse, almost like engine noise, but not the whine that a lot of people mention. Really just like muffled noise coming through the subs. I would imagine that grounding at the HU may do the same thing, but I will try it anyways just to be sure. It just puzzles me that the ground loop isolator changes the way the bass sounds and creates a turn on thump while getting rid of the turn off thump. Thanks for all the suggestions guys, keep them coming. I'm also going to try a deck swap just in case that fixes it. Its weird too because the buzzing is pretty much gone, and I think that was due to one of the rca plugs needing to be soldered. Now its just this thump and minor vibration. Its not even audible but you can feel the subs going.