I recently bought a Pioneer stereo system (FH-X700BT) for my 2008 Hyundai Sonata. The Sonata still has its factory speakers. The factory stereo was working fine, I just wanted something other than a CD player (aux, bt). After I connected the stereo wiring to the wiring harness and plugged it in, the music couldn't even be heard over the AC, whether from the CD or radio. I plugged the old stereo back in to be sure it was the new stereo causing the problem, and the sound was loud as expected. I am almost positive that none of my wire connections are bad, and pretty sure they are all matched up properly.

What should be my next step in troubleshooting? What are some things that could cause this, and things that I should be wary of? Should this be working normally or is there some sort of compatibility issue I overlooked?

  • The only thing I can think of is you're having a grounding issue with the new stereo, but would not have a clue. Commented Jun 1, 2014 at 17:21
  • There were 4 total grounding wires, 3 of them from the wiring harness and the last one from the stereo. I connected all four wires together and crimped them onto (pardon my lack of vocabulary) one of those grounding-circle-things and stuck that to a screw protruding from what seemed to be my car's chassis. Commented Jun 1, 2014 at 17:39
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    Make double sure it's actually making a ground. Did you clean the area for the ground, actually taking the finish off of the metal? Commented Jun 1, 2014 at 23:59
  • I didn't need to remove any finish. How could I be sure it is, and where else could I find a ground? Should I run a wire farther down to create one? Commented Jun 2, 2014 at 0:14
  • The best way to detect a good ground OS running a multi-meter continuity test between the place of the ground and the negative battery post, or a known good grounding location. Commented Jun 2, 2014 at 0:21

2 Answers 2


Sounds like no amplification. I don't know hyundai and all but I had a similar problem with my volvo, they had a separate amp box that you had to have a special aftermarket harness to wire to to kick in the amp. Otherwise all you got was very faint tinny, no bass sound.

  • Could it be something like this? crutchfield.com/p_142SLC4/Scosche-SLC4.html?tp=3486 Commented Jun 2, 2014 at 21:03
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    Sounds like it would do, although you might want to google a little further to see if other people have this problem with hyundais. It depends on where the amp in the stock setup is. In my volvo's case, the amp wasn't in the radio. Most aftermarket radios have a small amp in them and include preamp outs so you can set it up with your own amps. You may just want to go that route and not worry about what's already in the car.
    – stu
    Commented Jun 3, 2014 at 17:06
  • Another thing I was thinking, look at the wires/harness that used to go to the stock radio. Any unaccounted for wires? Any of them red or black? What I mean by unaccounted is that there may be wires that went into the radio that you're not wiring to that are tied to an amp somewhere in the car. By not using them, you're getting no amplification.
    – stu
    Commented Jun 3, 2014 at 17:08
  • An alternative answer to this question would be that I bought the wrong wiring harness. Read smile.amazon.com/review/R360O29INDBDY9/… for more information. Commented Jun 6, 2014 at 14:07

This may be because your speakers are wired out-of-phase ("+" to "+" on one speaker, and "+" to "-" on another. When this happens, the sound "cancels each other out" to some extent.

To test this, adjust the fader and balance to isolate a single speaker (say, the front-left speaker). Then bring in a second speaker. It they are wired out of phase, the volume and sound quality will decrease. Do this a few times, using different combinations of speakers (front-right and front-left, then front-right and back-right, etc), to make sure they all sound good together.

  • Thank you for you interest, and I did isolate each one. There didn't seem to be a difference in sounds. I double checked each wire once before, but I will triple check. Commented Jun 2, 2014 at 16:20
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    OK, thanks, I agree that it sounds like you have a different issue. Just to be clear, if the speakers aren't polarized correctly, each individual speaker will sound fine. It is only when you add in a second, reverse-polarized speaker that the sound would start to degrade... Good luck!
    – bitsmack
    Commented Jun 2, 2014 at 16:25

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