So i've had a sub and amp in my car for probably a month now, with no problems. A while ago i went out to my car on a hot day and the sub didn't work, but the amp was still getting power and all visible connections were fine. Before i parked my car that day, it was working fine though. A couple hours later, i went back and they worked fine.

Now, the last couple of days, when i start my car, the music plays but there's no bass from the sub. The power light on the amp is lit (the the thermal or protection lights are not) so I'm assuming that aspect is fine. BUT.... if i turn the volume up, at least half way, the sub starts up and sounds like it should. If i turn it down, the bass goes away all together...

All connections that i can see are fine, and no settings have been changed since this has been happening, so it's not like there's anything different.

The equipment being used is:
HU - JVC KW-AVX800
Amp - Rockford Fosgate p500-1bd
Subwoofer - P3D212

If there are anymore details that you think will make a difference, let me know, and i'll tell you what i can. Thanks.

 

check the wiring to the sub inside the box.

 

that's what i was thinking... i just didn't have the time to do it yet...

I'll probly check it out tomorrow and i'll post up what i find, thanks.

 

sounds like my issue i had the other day, i was horsing around with some honda on a double lane on-ramp and and when i hit the end my car bumped a bit and all of a sudden all my bass turned off, when i got home i checked out all the wiring, my 'autotek' insignia was still lit up in blue and my safe light was still green.
the answer was a blown fuse in the power line. not sure how the safe light and lit up blue lights under my sig was still operational but i guess thats why i dont makes amps,i just run 'em.

i couldnt solve the problem for 2 days before i relized i had not checked my fuse, haha

 

check the connection on your sub, if thats good, swap your fuses

 

So, i checked the fuses and everything seemed fine.
I took out the sub and checked the connection to the terminal and it a little loose. I redid the connections more securely, and it's been working fine ever since. Hopefully that's problem solved, if not, i'll post it up. Thanks for the help guys.

 

alright, i take back that last post. The problem has not gone away.
On my way to work today, everything was fine, 8 hours later when i left, the sub wasn't working.

is there anyway to test the outputs on the HU with a multi-meter or something of the sort?

 

check the RCA's coming from the head unit.

 

that's what i was thinking, but what would be the best way to do that?

 

haha, take the dash apart and have a look. it sounds like SOMETHING is loose so whenever you're driving...and the car is moving around...it's making sporadic connection causing your sub to go on and off.

stupid question...but check to see if the wire is still connected to the sub. is it push spring terminals? or the little spade type connectors?

 

i've checked the connections to the rca's in the back the first time i had a problem and it was fine. The terminals are screw type (that screw down to clamp the wire in place, and they're nice and tight.)

Is there anyway to actually test them? I was planning on testing a different output rather than the dedicated sub-out, and see if that works.

 

yeah, you can try that.

 

ill post back after i try it to let you know how it goes.

thanks for the help

 

So, i've tried using different outputs (2 different sets) and that didn't work. Then i decided to try a different sub, and that didn't work, so apparently it's not my sub that has the problem.

I remembered i had a multimeter and decided to give that a try. My amp has an output as well as the input, so i figured if there's a signal, the output would have it too. I tested the out, and it gave me a reading (Although i'm not too familiar with the multimeter so i dont really know what it means haha) so it seems like that's fine, but... as i was testing the output, the bass came back and the sub was working fine. I went into the house for a while, and then went out to check it again, and the sub wasn't working again. I used the multimeter on the output again, and it started working... any ideas?

 

Probably a loose wire going into the amp, jiggle every wire, and check the end point for the ground wire where you grounded it, make sure it's not loose or a weak connection.