Static pop on bumps

This one I cant quite figure out:

My girlfriend has a 2001 Civic EX with stock speakers.  We installed a subwoofer, but recently when she hits bumps there is a weird static from the right side speakers.  I tested all of the connections at the HU and at the speakers themselves, all are secure.  Anyone have any ideas what could cause this?  Is there a possible factory amp somewhere?

Let me know!  Thanks!

did you use a LOC or high level input?

if you used an LOC the switch the RCAs and see if the static switches sides, if it does then its in the LOC, or its connections.

to the speakers we are using the factory connections straight to the HU.  Is that what you are referring to?  I've never heard of LOC - what does that stand for?

to the sub amp is RCA

Then she has a replacement head unit installed.  That's why you didn't use a LOC.

Could be in the head unit itself.  The deck is powering the speakers, right?  Use ss-installer's advice but employ it in a different sense now:  switch the left/right wiring on the harness at the deck to see if the problem moves to the other side of the car.  At this point you should be able to tell where the problem lies...if the static appears on the other side the problem is within the deck.  If it stays on the same side the problem is in the wiring between the deck and the affected speakers.

And maybe those old OEM speakers are beat.

yeah, the sub install was what I assumed caused a problem.  That is why i checked the speaker connection on the back deck area and up front on the HU.  

Is there another place in the car where the wires have a connect - ie: harness - or do the wires go directly from the HU to the speakers?

found it - the relay we used for her lights came loose and was rattling around.  sad day.

for lights right now we are running the power from the same 4ga that the amp is powered with, is it that much better to run a dedicated cable from the batt for lights in the back?