Unusual Sound From Subwoofer, Help!

As the title states, I'm having issues with my subwoofer and i'm hoping you guys can help me out. I recently made the switch from a Tacoma to a 4runner. I bought the 4runner from a good friend of mine and it was already wired for a sub. He ran a Rockford Fosgate sub and amp with no issues for 8 months before I bought the 4runner from him. I hooked my sub woofer up from my previous truck using the wiring that was already in the 4runner. I'm using a JL 10 inch sub with a TMA amp (re-branded JL from what I understand). I purchased this set up off of craiglist and I had no issues with it in my tacmoa for a few years. When I put it in the 4runner the sub would intermittently go of when I would hit bumps in the road. I could also make the sub go off by beating on the dash, steering wheel, or any metal surface in the truck. This noise comes and goes. I was on a 13 hour road trip and it didn't go off once, then i hop in to go get groceries and it goes off with every bump I hit. The issue is only intermittent, so im unsure what could be causing the issue. Im no electrical or audio genious but I can understand enough to hold my own.

Things I have tried or checked-
1) Checked wiring for any shorts - all seems to be good
2) Ground all paint off the current ground- seemed to help but it still happens
3) Finally moved the ground wire directly to the frame with no avail
4) Replaced the remote wire- No change
5) Separated the power wire from RCA's throughout the cab - No change

Possible things to try or check could be-
1) Check RCA's on the back of the radio
2) Replace RCA's
Following that, I think my next step is to completely replace my amp and try that

I'm stumped because I had zero issues for years in my Tacoma but the 4runner is giving me fits.

Any advice, information that may help me solve the problem, or suggestions would be greatly appreciated.

 

you have to open up the amp and sub and look for the cold solder joint
or loose wire or garbage ground.

 

Just pulled the amp completely apart. Everything looks to be in order. I don't see any loose connections, bad solder points or any resistors that are burnt up. Any other suggestions would be great

 

either it is in the sub

or you have some other electrical gremlin loose in the vehicle that
is grounding itself out and the sub is revealing it