I have an 04' C230K with the stock comand nav stereo. I had a stereo shop install a JL audio sub-woofer and amp. It's causing power problems when starting the car and it blows the sub power amp after a week or so. The stereo shop keeps fixing it, but it's blown 3 amps so far.

When I start the car the first time of the day, some things like the power windows, sunroof, truck release, A/C etc., do not work for about 30 seconds. The subwoofer speaker does a few little pops, then after 30 seconds or so, everything works fine. But after about 2-3 weeks of this, it blows the sub power amp on starting the car. I get a message like "check alternator" or something. Once I disconnect the amp or after it blows, the car electrical sytem works fine.

They say they have no clue how to fix it and won't fix it again unless I come up with a fix myself. Nice, right? I thought that's what I was paying them for. Anyways, is there a way to fix it??? Thanks in advance.

 

You need to trace your source of power for the amp. If it drawing power from the nav command, then that is your problem. If it's drawing power from the battery, make sure there is fuse. From the sounds of it, your amp should not blow up, there must be a missing fuse to prevent that from occuring.

The nav command system should only wake up the amp when it's turn on, it should not be the source of power.

 

Yes, I believe that's how it's wired. I see a cable at the battery and the amp pops a little when the car is started and the stereo is OFF. That's what's weird. I see a fuse at the battery and of course the amp has fuses. The amp fuses were blown and when I replaced them, the amp was still blown and dead. Everytime the amp has blown, the stereo was OFF.

 

Okay.. I think you need to confirm something. The amp has only 2 source of power. You need to make sure the wire is going to the right place.

First thing. Source of power. The constant power for the amp. This should go to the battery, make sure there is a fuse holder with the right size fuse. If your amp is blown, then put in a smaller fuse. I don't know the correct fuse right now, so you need to check the amp manufacture specs on that. Now, once that is establish, make sure the amp has a fuse in it too, if there isn't, you should consider investing another type of amp that has one.

Last item, check for the other line that comes from the nav known as the remote line. This should be the wake up power line that turns on the amp when there is voltage to this wire.

I am wondering if you had the two switch around or if the wake up line (remote line) is attached to the wrong wire in the nav system. For example, to a constant 12v wire.

So with that mixed up, it is possible that the amp turns on every time your car is turn on, even with your nav is not on. The reason is, that wake up line has power so now the amp is waken up and since it is wake up, it starts to draw power from the constant 12v battery.

As for why it blew up, it's possible, that the wake up line (remote line) is a constant 12v+ for the nav which is too much voltage for this line and is blowing up the amp that way. At this time, it won't hurt to throw in a fuse on this remote line. If the fuse blows.. then it is for sure that the remote line is connected to the wire line from the nav system.

Also, do, check that there is fuses on the 12v+ constant to the amp.

Check out my diagram and see if it has all that to the amp.

 

This makes perfect sense. I hear the speaker pop when the nav is OFF, so it must be powered up. Good idea to put a fuse on the remote line too. I sent your suggestions to the installer and the new amp gets here next week to try again. I'll have them do what you suggested. Thanks a bunch! I owe ya if it works!

 

That is just to pinpoint the problem, but it does not solve your issue. You still need to find the correct remote wire for the amp in order for this to work correctly or it will just keep blowing out the fuse.

I still have a feeling that the remote wire that is connected is not a remote wire but a constant 12v+ wire for the nav system.

Perhaps you need to find the correct remote wire to use.

or read this thread for info.

https://mbworld.org/forums/c-class-w...questions.html

and this

https://mbworld.org/forums/audio-ele...nd-w203-2.html

Sorry, i don't have a command on my car so I won't be able to tell you the wire.

 

It sucks that ur installers and stereo shop don't know how to trouble shoot.

the popping noise is because they tap the remote to ignition instead of acc.. Tell them to use the cig lighter since is one of the only locations that mercedes have acc other than the ignition switch. This can also fix the blowing fuses on the amp. Also if the guy don't know what he is doing I wouldn't doubt if he pinched a wire and its grounding out somewhere. tell them to check the voltage at amp and batt to see if there is loss in power.

Hope this helps


EDIT:

Also if they would of actually took out the head unit. There's a thin black wire that is the amp turn on (technically is the power antenna) but turns on when the radio is on.

Another thing they could of used to avoid this problems is a PAC-Trunk Loc. (Its a high to low converter with remote turn on)

 

Cool. That's the answer you need. I had a feeling it has something to do with the remote wire.

Yes, I think either find the correct acc wire or use the cig lighter wire. Then again, the black wire as mention is a good idea as well since it is controlled by the radio turning on or off.

 

i would just have it wired to the cig wire. makes it easy and simple.

i dont think it would be a 12v constant. wouldnt that mean his amp is on all the time. i mean...if your amp is on while you take the keys out. then yeah.

 

check your grounds. Usually blown fuses, or in your cause amps are caused by a bad ground, either from a exposed wire some where or a bad ground source.

There's also a acc you can tap into the rear sam as well.

 

Thanks for the info. I'll ask them if they took the head unit out to connect the amp to the black wire.

After the last amp blew, they did add a PAC, but it still blew an amp. Actually faster then without it. The amp is out of the car now, but the PAC is still wired and I'm still getting electrically issues. Not as frequently, but still happens. It could be a ground issue too. Maybe I'll have them rip out all the wiring and start over.

 

Yeah, Not sure I want them messing with trying to take the head unit out. We'll see.

The last time the amp blew, it hummed bad when I started the car. I took the key out and it still hummed until I put the key in again and started the car. Then, it stoppped humming and the amp was blown.

 

Ok, I picked up the new amp and I'm taking it somewhere else to try again today. The original installer (Frank Electronics in WPB) said he's using a back right speaker wire as the remote wire. I bet this is the issue.

I emailed the stereo store owner your suggestions last week and he didn't even consult his installer like he said he did. I told him I didn't want them to try again.

Hopefully, this new installer will do it right.

 

I had another audio shop take a look at the car & wiring and they verified that it's correct. Everything worked fine for 3 days, and now it's poping on start of the car with the stereo off again. I'm sure it's going to blow the amp again shortly. They said they added a fuse to the remote wire too. We'll see. I think tomorrow I'm going to upgrade the amp to a better JL Audio amp and see if that helps. I currently have a JL audio J2 500.1. Maybe this will help.

 

Contact JL Audio & have a chat. They are great folks & on the high end side they are very helpful - sure car audio will be the same. Something is wrong!

 

I spoke to Jl Audio today. They were very nice. They think it's a short in a wire, so I'm going to have the audio shop rip out all the wiring and redo it on Thursday.

 

+1 - Good!

 

I had them rip out all the wiring and start over. I upgraded the amp to a better one with better protection so it shouldn't blow. It worked fine for 2 days and now I have the check battery/alternator warning light coming on again.

I've charged the battery with a battery tender from time to time, so it's not the battery. I guess it's time to take it in to MB and see what they find.

 

I'm starting to think that your regulator in the alternator is playing up & allowing higher than normal voltage or an AC spike. Have it checked.

 

That makes sense. I'm going to take it in to the shop and have it checked this week.

 

Disconnect your new amp in the meanwhile!!!

 

Had the car electrical system tested today and the alternator is bad. It's got a grounding issue. The shop wants $1,200.00 to replace it. WOW! They want over $900 for a new MB alternator. I'm only planning on keeping the car for another year or 2 max. So I think a refurbished $247 Valeo alternator with 2 year warrenty is fine, right?

 

Right!!!

 

Just got back from having a new alternator installed. I was cranking the stereo when BAM! "Check battery/alternator" warning blinked on. I then took it to another shop and had the battery tested and it's good. The tech recommended disconnection the amp for a few days and see if the warning comes on again. If not, plug the amp back in and see what happens.

I upgraded the amp to one that draws less amps, but maybe any additional amps will trigger this warning?

 

I had a MB dealer test the car and they told me the new refurbished alternator was bad. I had to return the refurbished one and buy a new Bosch alternator and now everything is fine. Finally!