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2002 C32 AMG
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Discussion Starter · #1 ·
Hey everyone, as some of you may know I was rear ended a few months ago. Insurance didn't approve any type of repair other than the body damage, and now I'm stuck with an Audio 30 unit that cuts in and out. The head unit itself appears normal when this happens. Meaning it has constant power, and the display screen doesn't cut out. Both the radio, and cd player stop working. Attempting to switch to CD player from radio during cut out results in the no cd error. Only the audio cuts out, as if the unit has been muted. Going over bumps will either kill the audio, or get it working again. So obviously I'm hoping it's a loose connection somewhere.

My question is what areas should I check first for this loose connection? Does this even sound like a loose connection? If so, would it likely be an electrical connection to the amplifier, or the fiber optic cable? I sometimes hear small cracks, and noises from the speakers even with the head unit powered down... The problem has got progressively worse since it first started a few days after getting my vehicle back from the body shop.
 

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2004 C230 Kompressor Sport Coupe
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You mean the cassette head unit? I thought that was the Audio 10. Anyway, if it is a break in the optical loop the code can be pulled with SDS, but I would check the wakeup connections first. Those are the ones with blue and blue-gray if memory serves. Also reseat the audio fuses. Is any water getting into the back? That can totally freak out the amp. Of course I have not been watching the NM weather lately so that may be a silly question.
 

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Discussion Starter · #3 ·
I believe the Audio 10 has the cd player built into the head unit. I may be wrong though... I have the bose setup with 5 disc CD changer. I'm off from work tomorrow, and plan to work on the car all day to see if I can fix this problem myself. I recently purchased the service DVD at the dealership, but it didn't have nearly as much information as I expected for paying $100 dollars...

Zeet, where exactly are the wakeup connections located? Service DVD does show how to remove the head unit so that's where I plan to start first... The rear is sealed tight, but to be honest I haven't even checked the rear fuse box yet. I'll make sure to do that first tomorrow. It has been mostly dry here in New Mexico...
 

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I do not totally understand the system, but I believe the head unit wakes up the amp through the CAN-bus and then sends data over the D2B ring. I know that if you disconnect the CAN-bus from the head unit, the amp no longer powers on. If you are getting noise out of the speakers it is coming on for some reason, perhaps losing power randomly.
 

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Discussion Starter · #5 · (Edited)
Yes, that is the normal operation of almost all head units. The first thing to do is check all fuses related to the audio system. The random power spikes I get in the speakers without the head unit powered would usually be related to power line, and not signal line. Not sure what effect a loose fiber optic would cause though... I found a good diagram on the service dvd that should help if I don't get anywhere checking the fuse box. I think the audio fuses are all in the driver side front panel...

By the way, being that everything is on a ring connection I am correct to assume any loose D2B connection would cause failure on the entire audio system?

Edit: Nevermind that's a dumb question...
 

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Discussion Starter · #6 ·
The sound amplifier fuse (26) appears to be fine, as does the radio fuse (46). I took apart the rear trunk area, and didn't see the amplifier. That is unless it's directly behind the subwoofer. Anyone know? By the way zeet, you were right about this being an Audio 10 unit... Audio 30 has the single disc built into head unit.
 

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Yes, that is the normal operation of almost all head units. The first thing to do is check all fuses related to the audio system. The random power spikes I get in the speakers without the head unit powered would usually be related to power line, and not signal line. Not sure what effect a loose fiber optic would cause though... I found a good diagram on the service dvd that should help if I don't get anywhere checking the fuse box. I think the audio fuses are all in the driver side front panel...

By the way, being that everything is on a ring connection I am correct to assume any loose D2B connection would cause failure on the entire audio system?

Edit: Nevermind that's a dumb question...
Not so dumb. My changer does not work. But the Audio 30 HU works when the D2B is disconnected from the back of the radio.
 

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The sound amplifier fuse (26) appears to be fine, as does the radio fuse (46). I took apart the rear trunk area, and didn't see the amplifier. That is unless it's directly behind the subwoofer. Anyone know? By the way zeet, you were right about this being an Audio 10 unit... Audio 30 has the single disc built into head unit.
Wrong. Audio 30 has casette. Maybe you are thinking of Audio 30 APS.
 

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Looks like it is behind the subwoofer, but the diagram is not so clear:

 

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Discussion Starter · #10 ·
Looks like the CD changer was a DIY job by the previous owner. The main bolt which holds the entire housing was screwed in slightly sideways, and the head was nearly stripped. I took the changer out real fast, and the D2B/power connections were secure in place. However, the wiring was not placed into the bracket on top of the housing, and I'm wondering if the D2B cable is getting bent... Didn't think about it at the time, but after removing, and reinstalling the CD changer I was getting real quick audio bursts, and the changer was detected again. I'm going to head back out, and route the cables correctly. Don't think it will help though... If that doesn't work the subwoofer encloser seemed easy enough to remove, so I'll check to see if the amplifier is behind it.

I'm trying to save removal of the head unit as last resort. It appears to be the most complicated. I'm not exactly sure how you unlock the center console air vents. I can see the locks, but how do they work?
 

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Discussion Starter · #11 · (Edited)
Wrong. Audio 30 has casette. Maybe you are thinking of Audio 30 APS.
Yes, sorry about that. I was thinking Audio 30 APS... At least that's cleared up now... :)
Not so dumb. My changer does not work. But the Audio 30 HU works when the D2B is disconnected from the back of the radio.
The head unit works meaning you still get audio, right?
 

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Removal of the head unit is pretty easy ... there's a pictoral DIY on InstallUniversity. Use a small flatblade screwdriver to unlock them, then the whole vent unit comes out. The whole center stack can be pulled in a few minutes even if you have never done it before.

If you need a HU I have a spare from my COMAND upgrade, but I'd bet it's the amp ... the crackling when it is off is sort of an ominous sign.
 

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Discussion Starter · #13 · (Edited)
Turns out the amplifier is not located behind the subwoofer enclosure. That is unless it's a small 2x4" little white box. I would assume what I found is way to small for an amplifier though. That small unit has a dial on it that looks, and turns just like what you would see on a wind up music box, or similar device? It's located near the SRS airbag container behind the metal frame.

Service DVD says if it's not located behind the rear right luggage compartment panel it should be located behind the side paneling of the rear right seat. How do you remove this panel though? There is no instructions...

If you need a HU I have a spare from my COMAND upgrade, but I'd bet it's the amp ... the crackling when it is off is sort of an ominous sign.
Thanks for the offer, but I'm thinking the same as you. It's most likely the amplifier. Still strange how bumps either cut the radio out, or fix it. That's the main reason for my assumption that it must be a loose connection, but after driving today it started cutting in, and out on perfectly smooth road. I probably don't even want to know how much a new amplifier will cost. I'm sure the accident dislodged a capacitor or something within the amp...
 

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I bet the amps fail rarely - I'd get one from a junkyard, since they will likely have a 90 day warranty on it. Should be a couple hundred or less if you haggle. That is, if you need one. Might be able to just pull it and have the board reworked and recoated if it's an internal solder fault, or just fix the connector if it's that.
 

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Yes, sorry about that. I was thinking Audio 30 APS... At least that's cleared up now... :)

The head unit works meaning you still get audio, right?
Yes.
 

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Discussion Starter · #16 ·
I do plan on inspecting the amplifier after it's removed. Still need to find out how the rear side panel is removed. I'm sure it's a clip based system like a lot of the other pieces of the vehicle, but where to start?
 

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Zeet, Do you know where I can find the speaker #280 in the diagram for 2005 C230K beside the dealer? $400 bucks at dealer not included labor, how hard to replace the speaker?
Thanks, Tom
 

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280 is the right hand door, right? Yeah, those are sort of absurdly priced. You can find them on the junkyard search at cat-part.com, or on eBay. If it's good when you get it, it's rare to fail.

To replace it you have to pull the door card. I haven't done that on a W203 but on a W210 it was pretty easy and the speaker was just held in with screws.

Before you buy a part, you should probably test the speaker. You can either swap sides, or use a small battery - google testing speakers to see instructions on that.
 

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Zeet, the one in the middle front dashboard, i believed it's a sub woofer. I brought to the dealer and they checked for me but $400 + Labor. I'll check on ebay and cat-part.
Thanks
 

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Yeah, those should be available on eBay, but they won't be listed on car-part.com. Any place that has the dash should have the speakers, you will just have to call them. I thought the speaker in the middle was just used for the phone?
 
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