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Discussion Starter · #1 ·
I had previously replaced the badly broken stock head unit with an aftermarket head unit, but then the face plate got stolen at some point and I never replaced it. So I've been without a car stereo for a couple years. Finally, I decided to get a new head unit with bluetooth and usb, and I installed it recently.

The head unit itself works, but...

At first, I was only getting sound through the speakers behind the seats and the little tweeters on the door. No sound was coming from the bigger speakers on the doors.

I couldn't figure out what was wrong, and then all of a sudden, the sound went out entirely. So I get no sound at all.

Any idea what the problem most likely is?
 

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2004 SLK200K
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Are the speakers wired directly to the new headunit or are you using an amp in the footwell, the problem may be with the amp if you have one ?

Silly question, but the mute button on the HU (if it has one) hasn't been pushed by accident ?
 

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2002 Blue SLK320 known as 'Silkie"
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This may end up as a game of twenty questions to get to the bottom of this so let's start with a couple of questions.
First - what make and model is the new head unit?
Second - what do you normally listen to in the car? (Radio? Bluetooth from the phone? CD?)
Third - Does the head unit work on Radio (FM band or DAB?)
Fourth - (sorry - got to ask) Is the volume turned up?
 

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Discussion Starter · #6 ·
Are the speakers wired directly to the new headunit or are you using an amp in the footwell, the problem may be with the amp if you have one ?
Hm, I don't know, it would be whatever the original wiring was... Only the head unit has ever been replaced, to my knowledge-- no rewiring or new speakers that I know of.

Silly question, but the mute button on the HU (if it has one) hasn't been pushed by accident ?
Nope.

This may end up as a game of twenty questions to get to the bottom of this so let's start with a couple of questions.
First - what make and model is the new head unit?
Second - what do you normally listen to in the car? (Radio? Bluetooth from the phone? CD?)
Third - Does the head unit work on Radio (FM band or DAB?)
Fourth - (sorry - got to ask) Is the volume turned up?
1. Head unit is a Pioneer MVH-X380BT.
2. Plan on listening mostly to iPhone via Bluetooth/USB, and occasionally radio.
3. The head unit looks to be working fine in all inputs (eg, sound from iPhone speakers cuts off after Bluetooth connects). But radio or Bluetooth input, there's no sound from speakers.
4. Yep volume turned up.

I'm confident the head unit itself isn't the problem, and fairly sure the wiring connections at the back of the unit are done right.
 

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If it was mine, I'd start from the beginning..

Take the radio out, put it on the bench and connect it up to a battery, connect a speaker to the speaker output and see if you're getting sound, or even just pull the radio out in the car and wire a speaker straight to the speaker output, just to check that the HU's working ok...

Apart from that, lift up the carpet etc in the passenger footwell to see if you have an amp installed and if so, in what condition it/its wiring, is in .
 

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2002 Blue SLK320 known as 'Silkie"
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1. Head unit is a Pioneer MVH-X380BT.
2. Plan on listening mostly to iPhone via Bluetooth/USB, and occasionally radio.
3. The head unit looks to be working fine in all inputs (eg, sound from iPhone speakers cuts off after Bluetooth connects). But radio or Bluetooth input, there's no sound from speakers.
4. Yep volume turned up.
Nice little head unit. No CD so easy to fit and use.

If your R170 has speakers behind the seats, you do realise these are probably sub-woofers and not 'rear speakers'. Also, if you have these speakers, you're likely to have a separate amp in the passenger footwell. Check that this amp is actually working and that it is switched on when the Pioneer head unit switches on. Do you hear anything from the speakers as you turn the head unit on (like a mild 'thump')?

There is a 'Mute' button on the head unit remote control. Have you tried pressing and un-pressing that button (with the remote in the car)?

Are there any error messages on the display?
 

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Discussion Starter · #9 ·
or even just pull the radio out in the car and wire a speaker straight to the speaker output, just to check that the HU's working ok...

Okay, I did this, and HU works!

Apart from that, lift up the carpet etc in the passenger footwell to see if you have an amp installed and if so, in what condition it/its wiring, is in .

Did this, too. I do have an amp. I disconnected the harness and check for voltage in the power lines coming in, and I can see there's 12V coming in and signal in the speaker lines.


How can I tell if the amp is still alive? I took apart the passenger door to try testing for voltage at the speaker input wires (with harness plugged back into amp). Didn't see any voltage, tho I'm not 100% sure I was doing it right. But if I was doing it right, I guess that would mean amp is busted? (The fuse on the amp is fine.)


Also, if you have these speakers, you're likely to have a separate amp in the passenger footwell. Check that this amp is actually working and that it is switched on when the Pioneer head unit switches on. Do you hear anything from the speakers as you turn the head unit on (like a mild 'thump')?

I do not hear any thump or anything at all from any of the speakers. How can I test if amp is working and "switched on when Pioneer head unit switches on"?


There is a 'Mute' button on the head unit remote control. Have you tried pressing and un-pressing that button (with the remote in the car)?

Muted and unmuted. Def not the problem.

Are there any error messages on the display?

No error messages.


I've read some comments about wiring HU directly to speakers. Can I do that simply by disconnecting the amp harness and connecting the incoming wire ports to the outgoing wire ports?


Also, the new HU has subwoofer wires, but the SLK's original wires don't have anything for them. How exactly does that work? What should I be doing?
 

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Discussion Starter · #13 ·
Okay, so I took the Bose amp harness out and attached wires from the left IN connectors to the left front and rear OUT connectors, and I get sound from the tweeter (next to door handle) and the subwoofer (behind seat) but not the midrange speaker (at the bottom of the door). SAME for the right side connections. On the right side, since I had the door taken apart, I attached the tweeter to the midrange lines and there was sound.

SO, do you reckon that means both my midrange speakers are dead? OR, something's not right so both midranges don't work?
 

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I'm sorry to bump an old thread. But from searching, this is the only thread that describes exactly the problem I have. Although I have yet to check if the bigger midrange door speakers work on another simple amp, I thought I would ask if this was ever resolved and how?

Thanks in advance!
 

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I'm sorry to bump an old thread. But from searching, this is the only thread that describes exactly the problem I have. Although I have yet to check if the bigger midrange door speakers work on another simple amp, I thought I would ask if this was ever resolved and how?

Thanks in advance!
Always better to just make a new thread for maximum exposure and help
 

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2002 Blue SLK320 known as 'Silkie"
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I'm sorry to bump an old thread. But from searching, this is the only thread that describes exactly the problem I have. Although I have yet to check if the bigger midrange door speakers work on another simple amp, I thought I would ask if this was ever resolved and how?

Thanks in advance!
I agree with Jeff, it's probably easier for you to start a new thread and reference this one to provide the continuity.

Happy to help you diagnose this once you've stated what your issue is and what your initial diagnosis is.
 
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