Car Stereos: No output, rca cables, portable cd player

Question
I'm trying to install an audio system in my car. Everything is wired from the deck to the amp to the subwoofers as it should be. The amp turns on, but I get no output to the subwoofers. We even tried using a different amp and different subs but got the same result. I've been told to find a subwoofer turn on feature on my headunit but there is none to be found. Any suggestions?

Deck - Sony CDX-GT820IP
Amp- KAC-9104D

Answer
Hi Andrew,

In a case like yours, I usually start by trying to isolate the problem between the subs, amp and head unit; but it sounds like you've done that, for the most part, by substituting a different amp/sub combo.  In that case, it's likely that the problem originates with the head unit or the RCA cables.

The sub on/off control in your head unit is just a function of the subwoofer volume; if you turn it all the way down, there will be no output.  I don't think there's another sub on/off selection.  

You might try switching the RCA's to a different output on the back of the head unit.  Right now you should be using the mono output, which is the RCA set that's on a pigtail.  You can try switching to the front or rear output, both of which are built into the deck's chassis.  Make sure you're not connected to the "Bus in" set; that won't produce any output at all.

If you're still not getting any sound on any output, then you'll want to try a different set of RCA cables--it's possible, if unlikely, that you have a set of defective RCA's.  Otherwise the defect would have to be in the head unit.

Again, I'm assuming that you've eliminated the amplifer and sub as the problem, by substituting another set.  You can verify this by trying another source with the sub; a portable CD player or iPod, with a Y-adapter to adapt the headphone jack to RCA plugs, would be good way to test the amplifier.  Just plug it into the amp's input jacks instead of the RCA cables from the head unit.  If you don't get any sound through the amp with the portable unit as a source, then your problem might be with the amp or subs after all.

Hope this helps!

Brian