My sister has a 99 Maxima with a Pioneer head unit, Jensen 200watt amp and a truck box with an 8" sub.

Here's the problem. Before the sub quit working completely, there was a low-level repetitive thumping coming from the sub whenever the stereo was on. I found a blown fuse on the amp so I replaced that. Then I traced all the wires and didn't find any exposed wiring. I turned everything back on and sub works very well, but I'm still getting the low-level thump along with a slight buzzing.
Whats going on?

 

you deck might be putting out a buzz in the rca cables or the rca cables might be going bad, or it might be the amp, try hooking up another set of rca's or another amp from the same hu to start narrowing down the noise problem, and check your ground to make sure it is solid

 

I'll give it a try, thanks.
Also, I noticed that when I turn the hazards on....I can hear it through the sub woofer. Surely thats not normal.

 

Are the power cables and RCAs running down the same side of the car?

 

Useless question; whether they are or not would have zero effect on his noise issues.

Where is your remote wire tapped?

 

'Scuse me, I thought that it could introduce noise into the RCA cables from the power cables.

 

Yes, the RCA cables, remote wire, and amp power wire are all running together. I had heard in the past that the power wires and speaker wires should be separated. Maybe I should do that.

The remote wire is tapped into the remote wire on the head unit..which is tapped into the remote wire from the original stereo.

 

my infinity basslink made random bumps a few times before it blew. i replaced the fuse but its still dead. it justs burn the other fuse without making any noise now. its sitting in my closet.i have no idea how to fix it. good luck with your. maybe ill get a good idea from your thread.

 

That's what I was always told as well. It couldn't hurt, just a little bit of work.

 

Does the buzz/thump/noise only happen when the car is running or is it all the time?

 

i see this a lot with older pioneer decks. The rca output board goes bad on their radios a lot. then again, it could also be the amp going bad as well. You had mentioned that a fuse was blown on the amp before you got it working again? It may be something internal on the amp that has gone bad as well.... Most of the time the rca's and the power wire for a sub will not give interference or "engine noise" but it all depends on the quality of the wires used. If the power wire isnt braided or the rca's aren't insulated well enough then that could be a problem too.