2000 LX coupe rear speakers not working

Qwertyfish01

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I've spent a bit of time trying to figure this one out, but I don't know what I'm doing. The rear deck subwoofers in my car are broken, making everything have no bass and sound quieter than it should.

So far, I've verified that the speakers themselves work just fine with a multimeter. Then, I found that the speakers are connected to a wire going into this small black plastic box with a TDK logo imprinted on it. I have no idea what this box is or whether it's the culprit, but there are other wires coming out of it that leads somewhere I can't see, behind the carpet on the walls of the trunk. Does anyone know whether this black box would contribute to my problem? What do I have to replace to make the audio system work?
 

Adhmuz

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By rear subwoofers I'm assuming you mean the rear deck 6x9 speakers.

That TDK box doesn't sound stock to the car, do you have any history of the car, how long you've owned, when the last time the rear deck speakers worked would be a good start.

Also good to know is does the car have an aftermarket head unit installed or is it the original.

Now I can only speculate with limited information but that TDK box might be part of an after market head unit that was removed from the car before selling it, and whatever was put back in it's place, be it stock or another cheaper after market head unit, it might not have the right connection to use that mystery TDK box, which could be an amplifier of sorts.

In my 98 I had no such box and my speakers were all wired right to the factory stereo.

Again, if you could provide a little history of the vehicle and what it currently has as far as speakers and stereo/head unit I'm sure it will be a little more clear to diagnose.
 

Qwertyfish01

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I don't have a history of the car, but it came with the stock head unit and everything. I only got it recently so those rear speakers have never worked the whole time I've had it. I did some googling and found this picture of the box in question: https://imgur.com/a/yriI6Yc

Some results say it's a rear window defrost module (then why would the speakers be connected?), others say it's an antenna amplifier. I don't really know which.
 

Adhmuz

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Alright, I can confirm my car had that same TDK box in the trunk under the deck, and it had nothing to do with my speakers. Judging by the size of the wires coming out of it I would say it was a module for the rear defrost.

The only thing you can do now is remove the factory radio and check the wiring behind it to see if it was tampered with, look for any evidence that a after market radio was once connected or some kind of auxiliary amp was installed in the car.

If everything looks untouched you'll need to check the continuity of the wires from the front of the car to the rear, I believe the rear right speaker is blue/yellow and white/gray.

Something really silly to ask, the factory head unit has a fader option, be sure to check if its not turned all the way forward.
 

Qwertyfish01

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I have no idea how I missed this, it must have not come into my email for some reason, so I'm just seeing this now I apologize.

From what I remember, (I last looked at this when it was still warm enough to do so), the only connection the speakers had to anything was through a wire that ran into that black box. Thinking about it now, it probably just looked like that, more logically the wires would just go to the head unit. Which, by the way, I did actually mess with the fader to make sure it wasn't set all the way to the front. It was in the middle, and actually setting it to the back makes it go quiet. When I first got the car it had this cheap garbage head unit which was totally broken and only drove one of the speakers, but the original unit was still around so I replaced it. It's no big deal, I can just get a bluetooth cassette for like $20.

When I can, I'll use a multimeter to test the continuity between the pins on cable that goes into the head unit and the connector that goes into the rear speaker. I'll post again when I get those results. If there's continuity, the speakers are broken, and if there's none then it's a wiring issue. (correct me if i'm wrong.)
 

Qwertyfish01

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I’m in the car right now, just used my multimeter to test the continuity from the red/yellow wire in the radio harness connector to the right rear speaker. I’m no electrician, so I don’t know if this actually confirms anything, but when i touch the wire to that hole in the connector the number on my multimeter jumps from 0002 to 0007. I assume that means there is continuity.

So, if there is continuity, what is the problem? I’m assuming the speaker. It just seems so unlikely that BOTH rear deck speakers are broken, and not even any others in the car.
 

Qwertyfish01

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I’m a complete idiot. yesterday i didn’t just have the multimeter in the wrong mode, I wasn’t even connecting it correctly. With a little help, I am now kind of sure that this is a wiring problem.

I used a length of solder as a jumper on the plug that goes into the rear speaker, and I read the continuity between the pins on the head unit connector that correspond to the colors of the wires going into the rear speaker. (Identified the colors on the speaker plug and saw the same wire colors going into the radio connector.) No matter what I tried, there was no continuity. Multimeter read OL the whole time. The fact that it is a wiring problem sounds like a huge hassle so I think this is a problem that will stay unfixed.

Thanks, Adhmuz, for the help! And if you’re somebody finding this on google years later or something, there you go lol.
 

Adhmuz

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Depending on your level of interest in having working rear speakers, running wire back there isn't all that hard. I had run wires from the back to the front doors when I had an amp in my car, along with 3 sets of analog audio signal wires and power from the battery. Most direct path is right down the center of the car, you'll need to remove the center console and back seat to do this mainly to gain enough access to pass the wires under the carpet covering the tunnel. But overall not that difficult, takes a couple hours.

You're welcome for the help, glad you were able to identify the problem you were having.
 
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