Car Stereos: No sound from powered sub, mercury mountaineer, rca cables

Question
QUESTION: i Have the 2003 mercury mountaineer and i have all the wires ran for a aftermarket powered sub. i have pwer to the sub cause the lights turn on but there is no sound i also have the factory sub and amp installed and they play just fine can you tell my why it doesnt have sound!? i have my remote wire for the powered sub ran to the aftermarket stereo i dont kno wat the prob is the pwered sub is a ksc-wd250 and the head unit is a jvc s15 i believe please help if possible

ANSWER: Hi Steven,

What are you using for the subwoofer's audio source?  Do you have RCA cables running to the after-market deck, or are you connected to the factory speaker wires with a high-level input?  

If the power lights are coming on, it doesn't sound like the remote wire will be the problem.  The question is whether the sound is getting to the sub in the first place.   That's why I'm wondering about the audio source.

If you can follow up with the details about how your sub is connected, I'll see if I can help you troubleshoot your problem.

Thanks

Brian

---------- FOLLOW-UP ----------

QUESTION: the outputs for the powered subwoofer is connected to the outputs for the factory sub and amp. i have the factory sub and amp connected from the 8 pin wiring harness coming from the vehicle itself. i wired the output device in myself. i just spliced an extra pair of rca's i had laying around found the wiring diagram and connected it to the outputs on the back of the aftermarket HU. Now the aftermarket sub and amp is connected to the same wires but they are spliced into the outputs of the factory amp and sub. do i need to run a totally different output for the  aftermarket sub and amd and if so where do i hook it into the back of the aftermarket HU i hope this is enough for you to help me

Answer
Hi Steven,

Thanks for the follow-up; I think I have enough to go on now.

If I'm understanding you correctly, you have the green, green/black, violet, and violet/black wires from the sub run up to your head unit, and they're connected to the same signal wires that feed the factory amp and sub.  Is that correct?

If this is the case, then the problem is that you're connecting high-level input wires to a low-level source.  The green and violet wires are meant to be connected to speaker wires, but the signal wires in the 8-pin plug are just carrying a low-level signal to the factory amplifier.  They don't have enough voltage to adequately supply the sub's high level inputs.

There are three possible fixes:

First, you could connect the green and violet wires from the subwoofer to the rear speaker outputs at the deck, instead of to the wiring in the 8-pin plug.  This should give you the output you need to make the powered sub work.  However, you wouldn't be able to use the deck's high-pass filter (if it's equipped with this feature).  You also wouldn't be able to use the deck's subwoofer level control (again, if it's equipped) to adjust the after-market sub.

The second option is to connect the sub's input wires to the output wires at the factory sub amp.  Again, this would give you the high-level output that you need, and you'll be able to control the after-market sub along with the factory sub.  The only downside to this option is that it will take a lot of work, because you'd need to remove the interior panel on passenger side of the cargo area to get to the factory amplifier.

The third option is to use RCA cables to supply the powered sub with the audio signal, instead of the green and violet wires.  The sub should have RCA input jacks; you can run these to the same head unit RCA outputs that you're currently using for the factory sub. You would need a pair of 1M-2F RCA Y-adapters to do this.  This should work about the same as the second option, but should be less work.  However, you'd have to buy a set of RCA cables and Y-adapters.

Hope this helps!

Brian