Need help figuring out why there is no sound in subwoofer and rear speaker

Midnight_Raven

Midnight_Raven

Legendary Member
Joined
21 September 2002
Messages
2,039
Location
Lawrence, MA
Alright guys, about two weeks ago I started my repairs on the car. The rear speaker and sub aren't producing sound. I opened up the aftermarker head unit and noticed the wires for the rear and sub were cut. :confused: Either way I splice the connections back together and thinking that was the fix. I try it out and again no sound. I then start to try to find the source of the problem. I was able to get sound from the rear speaker if I bypassed the sub box. So I assumed it was the sub. I open it up and the only thing I can think of is that the amp is bad in the sub.

I ordered a repaired sub amp from SOS and it arrived today. I install the new amp hook everything back up and I STILL HAVE NO SOUND! argh :mad:.

The wires don't look damaged in the subwoofer box. I checked continuity from the sub main relay B end and the sub box power connector end (yellow/red wire), I have continuity. The black wire that is part of the power connector also has continuity to the aftermarket head unit. The signal wires all are good because I'm able to get sound from the rear speaker when I jump the sub box. Everything seems to be wired up correctly according to the wiring diagram in the service manual. I even checked the 20AMP fuse that bridges the connection between the battery and the sub main relay. That's good too.

I have no idea what to do anymore. Anyone has any idea what could be wrong?
 
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Yeah pull it all out and put in a real system. LOL... I'm at a loss too seems you've checked everything. I'd contact BrianK.
 
Midnight_Raven said:
. I opened up the aftermarker head unit and noticed the wires for the rear and sub were cut. :confused:
Click to expand...
When I see "aftermarket" and "wires .. cut", it could be anything. Your comment about "rear and sub were cut" makes me suspicious. Are you aware that there is no wiring for the 'rear' and 'sub' separately? It is one and the same. And the head unit does not produce a 'rear' channel .. it just sends the L and R channels to the amp that's in the sub enclosure which merges the two and sends it to the rear speaker .. and also strips out and amplifies the low frequencies and sends them to the sub.

So, the real question is what state is the OEM wiring harness in? Is there some kind of adapter harness between the aftermarket head and the OEM wiring harness .. or is there just a lot of spliced wire? What is connected to the 4 wires (L +/- and R +/-) OEM wiring that goes to the sub? I'm also confused by your comment that "I was able to get sound from the rear speaker if I bypassed the sub box". By bypassing the 'sub box', you're really bypassing the rear speaker amp and if this was the OEM head unit, you'd be driving it with just pre-amp levels which I suspect you'd have trouble hearing. If you have lots of volume then I suspect that the aftermarket head unit has some amplification in it .. which would then make me question why the door speakers are working unless someone has bypassed those amps as well.

Too many questions at this point to suggest much else other than questions.
 
NSX2398 said:
It is one and the same. And the head unit does not produce a 'rear' channel .. it just sends the L and R channels to the amp that's in the sub enclosure which merges the two and sends it to the rear speaker .. and also strips out and amplifies the low frequencies and sends them to the sub.
Click to expand...

Ian this is great info. You are certain of this? No particular output exists on the HU for center and sub? Is the center's amp part of the sub box?
 
NSX2398 said:
When I see "aftermarket" and "wires .. cut", it could be anything. Your comment about "rear and sub were cut" makes me suspicious. Are you aware that there is no wiring for the 'rear' and 'sub' separately? It is one and the same. And the head unit does not produce a 'rear' channel .. it just sends the L and R channels to the amp that's in the sub enclosure which merges the two and sends it to the rear speaker .. and also strips out and amplifies the low frequencies and sends them to the sub.

So, the real question is what state is the OEM wiring harness in? Is there some kind of adapter harness between the aftermarket head and the OEM wiring harness .. or is there just a lot of spliced wire? What is connected to the 4 wires (L +/- and R +/-) OEM wiring that goes to the sub? I'm also confused by your comment that "I was able to get sound from the rear speaker if I bypassed the sub box". By bypassing the 'sub box', you're really bypassing the rear speaker amp and if this was the OEM head unit, you'd be driving it with just pre-amp levels which I suspect you'd have trouble hearing. If you have lots of volume then I suspect that the aftermarket head unit has some amplification in it .. which would then make me question why the door speakers are working unless someone has bypassed those amps as well.

Too many questions at this point to suggest much else other than questions.
Click to expand...

The aftermarket head unit has an adapter cable that goes between the connector that would normally hook up to the factory head unit. That adapter cable had 4 wires cut which coincides with the 2 white and orange pair of wires that are the signal wires for the rear amp and sub. None of the factory wires were cut, just the adapter aftermarket cable harness.

Going to the subwoofer there are 4 signal wires. These connect to the sub box and inside the sub box they get spliced together before reaching the amp. After the signal go through the amp they connect to the subwoofer speaker and out to the rear speakers via the same input connector. Below is a diagram in which I was able to get sound to the rear speaker by jumping the amp with some paper clips. This is what led me to believe the amp was bad so I ordered a new one but still no sound with the new amp.

Myspeakerproblems.png


I'm wondering could it be that the polarity of the head unit is opposite of what the amp is suppose to receive so it won't let the signal through because it detects bad wiring?

The door speakers setup is strange. They are MB Quart speakers. It looks like they cut the amplification power source and just hooked up the signal wires to what appears to be a small amp and then the wiring goes to the speaker. So I don't get how it amplifies the signal if there is no additional power source being inputted but it works. The small amp thing looks like the small box in the image below.
41zU03vM2NL._SL500_AA300_.jpg
. Either way the door speakers work fine for now so I'm not too concerned about those.
 
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That's a crossover not a small amp. Do you have the full diagram of the factory stereo?
 
TURBO2GO said:
Ian this is great info. You are certain of this? No particular output exists on the HU for center and sub? Is the center's amp part of the sub box?
Click to expand...
Yes, I'm sure and the wiring diagram that Midnight_Raven posted confirms it. The amp inside the subwoofer enclosure has separate circuits for the sub and for the center-rear speaker. I should clarify my earlier comment that "there is no wiring for the 'rear' and 'sub' separately". What I meant was that there is no separate channels for the rear and sub .. that they just use the existing L and R channels. As the diagram shows, there is separate wiring coming out of the head unit that goes to the sub.

I don't know for sure but I presume these L & R putputs are not exactly the same as the L & R wiring that goes to the door speakers .. because you can add more base via the control on the head unit so the head unit must enhance the lower frequencies before they leave on those wires.
 
Midnight_Raven said:
The aftermarket head unit has an adapter cable that goes between the connector that would normally hook up to the factory head unit. That adapter cable had 4 wires cut which coincides with the 2 white and orange pair of wires that are the signal wires for the rear amp and sub. None of the factory wires were cut, just the adapter aftermarket cable harness.
So, if the adapter cable has those 4 wires cut, then I think you're confirming that there is no path for the L & R sub/rear speaker signals to get to the amp in the sub enclosure.

Midnight_Raven said:
Below is a diagram in which I was able to get sound to the rear speaker by jumping the amp with some paper clips.
Click to expand...
I have no idea as to how you were able to do this given your earlier confirmation that the wiring from the aftermarket head is cut at the adapter and not connected to the factory wiring.

Midnight_Raven said:
Going to the subwoofer there are 4 signal wires.
Click to expand...
correct, if you're looking at the sub enclosure, these would be the 4 OEM pre-amp outputs from the head unit (plus power and ground). But, again, these are part of the factory harness which goes back to the head unit and you've told me that the corresponding connections in the adapter from the aftermarket head have been cut so there should be no signal on these wires.
Midnight_Raven said:
These connect to the sub box and inside the sub box they get spliced together before reaching the amp. After the signal go through the amp they connect to the subwoofer speaker and out to the rear speakers via the same input connector. This is what led me to believe the amp was bad so I ordered a new one but still no sound with the new amp.
Click to expand...
Good logic .. but other reasons are: (1) no input signals (as I'm concluding), or (2) no power to the amp (as Brian K has suggested)
Midnight_Raven said:
The door speakers setup is strange. They are MB Quart speakers. It looks like they cut the amplification power source and just hooked up the signal wires to what appears to be a small amp and then the wiring goes to the speaker. So I don't get how it amplifies the signal if there is no additional power source being inputted but it works. The small amp thing looks like the small box in the image below. Either way the door speakers work fine for now so I'm not too concerned about those.
Click to expand...
The OEM door amp/speaker combination is enclosed in a black plastic box so I presume they've just removed it and installed the new speakers and crossover (as TURBO2GO has suggested). They'd be able to just ignore the power/gnd wiring but use the OEM signal wiring which the adapter wiring harness connects to the new head unit. But this suggests that the new head unit is not outputting pre-amp signal levels but rather more likely speaker output levels. If that is the case, (and if I'm not correct about the cut adapter harness wires) then it would be outputting those same high levels to the sub amp and maybe it's shutting down to protect the amp circuitry (best case) or maybe they blew the original subamp and you may have just blown the new one you put in.
Click to expand...
 
NSX2398 said:
Midnight_Raven said:
The aftermarket head unit has an adapter cable that goes between the connector that would normally hook up to the factory head unit. That adapter cable had 4 wires cut which coincides with the 2 white and orange pair of wires that are the signal wires for the rear amp and sub. None of the factory wires were cut, just the adapter aftermarket cable harness.
Click to expand...
So, if the adapter cable has those 4 wires cut, then I think you're confirming that there is no path for the L & R sub/rear speaker signals to get to the amp in the sub enclosure.
Click to expand...

Correct I suspected that the signal wires for the rear and sub are really just the rear right and left signal wires.

NSX2398 said:
I have no idea as to how you were able to do this given your earlier confirmation that the wiring from the aftermarket head is cut at the adapter and not connected to the factory wiring.
Click to expand...

If you re-read my first post I stated that I spliced these 4 wires back together on the aftermarket adapter end hence I'm able to get sound in the rear by bypassing the sub.

It sounds like my pioneer AVIC-D3 head unit is sending speaker level audio signal vs pre-amp signal since you're saying the doors shouldn't be loud either then without an amp and pre-speaker signal strength. I may just open the sub box and jump the amp internally and see what happens. My only concern is if I will overheat/destroy the head unit trying to do that since it's now powering 4 speakers.

Either way thanks guy for the help. I have basic understanding of how circuits work and how to wire stuff together but as you can see I couldn't tell the difference between a crossover and an amp. My sound system expertise is non-existent hehe.
 
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Briank said:
Does the sub make a quiet hissing sound when you have the stereo on? If not then the relay for the bose amp(s) is not is not being turned on when the stereo is on.
Click to expand...

I haven't been able to hear any sort of quiet hissing sound from the sub or the rear speaker. I swapped the relays around in my sub main relay B box and still not getting it. I find it hard to believe I have two bad relays but I guess I can always go to the auto parts and see if I can get a new one to eliminate that possibility.
 
It appears that your head unit can drive 4 x 4 to 8 ohm speakers by default but can also supply pre-amp outputs to an external amp via a separate connector (which I suspect you're not doing). This explains why you were able to drive the rear speaker by bypassing the sub amp. It also confirms my earlier conclusion that you're likely overdriving the sub amp. However, you could likely get output from the sub by bypassing the sub amp and going directly to the sub speaker terminals as well. In any case, you don't need the sub amp.

If you look at your head unit's installation manual (http://www.pioneerelectronics.com/p...221/417372568AVICD3InstallationManual0221.pdf), you'll see on PDF p10 (manual p9), that it can drive 2 x 4 ohm rear speakers or 1 x 2 ohm sub. But I see that there's also a warning on PDF p7 (manual p6) that you should never drive speakers that aren't in the 4-8 ohm range. You should be aware that the OEM speakers are 2 ohm .. which is likely not a problem with your door speakers since your replacements are likely in that range .. but you may blow your rear speaker if you put too much power to it.

Note that the instructions say your head unit can either drive a 2 ohm sub OR 2 x 4 ohm speakers but not both. If you try to bypass the sub amp and drive both the rear speaker and the sub, the effective impedance will be 1 ohm and you risk blowing the rear channel amp in the head unit. If you don't care about the rear speaker that much, just bypass the sub amp and use the rear output to drive the sub and you'll be good. Note that in this mode, the sub is only being driven off the right channel as opposed to the OEM which uses merges both L and R for both the sub and rear speaker.

If you insist on using the rear speaker, I'm not sure what the best solution is. You'll have to either get a separate sub amp or a separate amp for the rear speaker and you'd have to use the pre-amp outputs on the head unit to source either of those amp solutions. In either case, installing a separate amp takes some effort and space is at a premium. I put mine behind the drivers seat but others have put them in the trunk. If you have plans to replace the sub with a larger unit anyway, then the decision is likely easier. Personally, I'd give up the rear speaker for now and drive the sub directly from the head unit... and then if you put in a sub amp later, you can use the head unit to drive the rear speaker at that time.
 
Awesome information guys. I think I'm not going to use the sub but instead the rear speaker and see how that works. I don't really need the sub because the door speakers have enough bass for me now.

Thanks for all your help NSX2398 and Briank
 
Briank said:
Make sure you unplug the 2 pin connector at the foot well speaker so the amp never gets power. Hot wiring the center speaker to the signal is amp output to amp input.
Click to expand...

Thanks, I've just finished rewiring the sub box. So the rear and sub are independent of each other now. I also removed that amp power connector inside the sub box so the amp won't ever get power. I just tried out the rear and sub independently. I think I'll leave the sub because it is hard to hear the bass with the car running.
 
Raven where can I get the full electric diagram to the radio speaker wiring? The one you partially posted above?
 

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