After searching on here and not finding anything useful, I decided to write up a DIY for an amplified subwoofer installation. I have a 2010 C300 with the standard sound system (Audio 20 is what I think it's called), but I'm sure all W204s will be very similar no matter what sound system you have.

The stock sound system is decent, but could use more bass (especially in the rear). I will be installing the bazooka in the trunk, but I may opt for the Sound Ordnance B-8PT that Crutchfield sells because it is flat & thin and can be mounted many different places on the C300.

Step 1: Run power wire from battery to rear of car:

What I did first is look into the engine bay (on the right passenger side around the battery). I couldn't find any unused rubber plugs other than the one huge one located the pass side fender.

I went inside the car next and removed the mat, side plastic trim (just pull up hard to remove), the molding (just pull it off), the inner upper plastic cover (has 3 T-20 torx scews in the front), and side front plastic trim piece (remove by pulling it towards yourself so the clips can dislodge from the metal frame).

After pulling the carpert back in the front on the pass side, I noticed an unused rubber grommet (located up top in the center and to the left of the huge wiring harness that comes in from the engine compartment) which I decided to use to run my power wire from the battery.



You have to remove the cover above the battery (which is held in with 3 clips up top) and then the battery in the engine bay to access this grommet. You can see where the grommet is located. I just poked a small hole through it and ran the power wire through the center of the grommet.



After that, I reinstalled the battery and installed the in-line fuse to the positive battery terminal. I did not connect the power wire to the in-line fuse wire, this will be done last after everything else is connected.




Next, connect the negative terminal and reinstall the plastic cover above the battery. You will have to readjust some things (time, date, etc) in the car, the radio presets were saved so I just had to reset the date and time in my car.

Then, go back inside the front pass side area and run the power wire down the side of the car (where all the other wires are):



There is a plastic bracket that holds all the wires as they run along the side of the car. This plastic bracket has clips up top which you pop off to open up the top to place the wire down in where all the other wires are. I used a coat hander and taped the power wire to run it across the B Pillar to the rear door area:



That's as far as I got with the power wire for now. I buttoned up everything in the front pass side area and focused my attention to the rear of the car.

Step 2: Run high level wires from rear speakers to rear of car:

Mercedes decided to install the rear speakers in the door which makes it more difficult to run high level wires. However, it was rather simple to do, just took some time.

You have to remove the interior B Pillar covers to access the interior wiring harness for the rear speakers. I did not take off the door panel to see what color the speaker wires were because most car companies switch the colors when the wire runs from the door to inside the car.

To remove the interior B Pillar covers, pull up on the molding to reveal 3 clips on each side. These are the same clips that were on the front side panel on the pass side. I undid the top 2 first (you have to again pull the clip out towards yourself) and then the middle and bottom ones came off like butter.

I started with the driver side first. Once you remove the door harness from inside the pillar, the harness will look like this (8 wires total):



The speakers wires on the driver side (left side) of the car are circled in yellow. They are Pink (+) and Brown/Pink (-) in color. I cut each wire and tied together 2 new wires (one for + and one for -) to the 2 speaker wires and used butt connectors to crimp everything together. I checked everything with a volt meter before I did any cutting. Speakers ususally have a small amount of voltage (0.01 to .06 volts) running through them.



Tape everything back together and plug the harness back in and verify that the speaker works (simply just turn on the radio) before taping everything back together. Once you confirm that the speaker works, use 2 new zip ties to attached the harness to the pillar like so:



You will have to run the wires through the plastic brackets on the side on the car. I didn't run the wires any further because I wanted to do the other side (pass side).

Do the pass side in the same fashion as you did the driver side. The harness on the pass side is the same as it is on the driver side. However, the wire colors are different. The speakers wires are in the same location on the harness as the driver side:



Cut the wires and add two new wires (+ and - high level inputs) to one end as you just did on the driver side. Use butt connectors to connect both ends together. The speaker wires on the driver side are White (+) and Brown/White (-). Plug the harness back in and verify that the speakers works when you turn on the radio. Once you get confirmation, tape everything up and run the wires down the side of the car as so:



All that is left to do now (after reinstalling the B Pillar interior covers) is run the power wire and 4 high level inputs (2 on the pass side, 2 on the driver side) from the rear seat area to the rear trunk.

This is where I stopped for the day because it started raining. I will finish the install during this week and will complete the write up later in the week.

Hope this helps anyone who wants to install an amplified subwoofer into their C300 or C350. Getting to this point took me about 3 hours because I took my time and installed everything neatly. I am very new to my new car (only 2 days old and has a mere 52 miles on it). I just picked the car up yesterday so I am not used to it just yet, but after doing this job, I feel very comfortable working on the car now.

Step 3: Continue wiring from B Pillars to Rear Trunk:

Follow the black side plastic covers to the rear seat. What I did first was remove the lower seat section. All you do is pull up hard in the front and the seat will pop up. Next, you push the seat towards the rear and then up to unhook them from the metal supports (circled in red). I also removed removed the T-25 torx bolt (circled in yellow) on the upper seat portion to give myself more room:



You don't have to remove the top seat portion, you just have to free the latches at the top so you can tilt the seat forward to give yoruself enough room to squeeze the wires past. To unlatch the top seat section, you have to undo the latches which is done inside the trunk. Below is a pic which shows a hole where the latch is. I stuck a screwdriver in the hole and pushed towards the driver side (push the latch in the pass side hole towards the driver side as well):





Now that you can tilt the seat forward, run the wires inside the black plastic brackets and up the rear where the factory wires are. You have to tilt the seat forward a bit. If the seat doesn't tilt forward enough, undo the 2 16mm nuts at the bottom of the seat:





I taped the my high level wires to the factory wires, but I had to use a zip tie on the pass side as the factory harness was much thicker and harder to move. Once you run all the wires, you should be inside the trunk like so:



You can see my 2 high level wires from the left side and 2 high level wires from the right side as well as the red power wire from the right side. Cut the wires as needed to the bazooka harness and use a ground contact in the trunk to connect the ground wire. I kept all the wires together along the rear seat bottom. Put the black plastic cover and carpet back in and it should look like this:



All that is left to do is to strap the bazooka down with 2 straps. I will drill 4 holes into the seat frame and mount the brackets for the bazooka onto the rear seat. I didn't do it today, I'll do it tomorrow, but I don't think anyone needs a picture of that.

I connected the power wire to the in-line fuse wire in the engine bay and hid it under the black plastic cover above the battery. You can barely see it:



That's pretty much it. I installed a 100W 8 inch amplified bazooka (BTA8100) so I didn't have to run a huge power wire. Also, I'm not running a remote turn on wire, I'm just using the auto-turn on feature on the bazooka. You should run the recommended gauge power wire for your specific product that you plan on installing. The 8 inch bazooka sounds really good and adds much needed bass in the rear.

I'm happy how things came out and I hope you guys find this DIY useful for your installations. As I was finishing up, UPS dropped of my Eibach Pro-Kit springs so I'm on the the next project.

 

pretty much what i did =]

 

Just what I need, thanks for the awesome DIY lewylou78!

 

Great DIY but I have a little input.
That power cable looks a little light. What is the power rating on the sub amp you ran? If the wire is too thin, it can cause it to overheat and possible start a fire. I would have run at least an 8 gauge.
If you would have tapped into the line levels at the head unit, it probably would have been easier than pulling 2 B-pillars. The head unit is very easy to remove.
Just a little advice.

 

Thanks for the advice, but I'm not running a separate amp and subwoofer, I'm just installing a 100W amplified bazooka (BTA8100). You only need a 16 gauge or larger power wire for the 100W bazookas. The 200W or 250W bazookas need 12 gauge or larger (8 or 10 gauge if one prefers).

I'm actually running a double insulated 14 gauge wire (instead of the recommended 16 gauge) for the power wire and 16 gauge wire for the speakers wires (high level inputs) for my 100W amplified bazooka. According to Bazooka, that will suffice.

Taking off all the interior pieces (especially the B Pillar covers) took very little time by the way.

 

Wow! That must be an efficient amp.

 

nice DIY i will def use this thread for my sub installation.

 

How does the Bazooka(s) sound in the car? I was debating installing my previous setup in to the car but it would dominate my truck and the Lexan box is ridiculously heavy so there is no way I could get my golf clubs in and out easily.

I've thought about Bazooka's but I couldn't find them locally here, only online and I'd like to hear how they sound first.

Thanks for the DIY!

 

They sound great (when hooked up correctly). They give just enough bass. I've been using amplified bazookas in my VW's for years. Plus they are quick and easy to remove.

Haven't finished with install in the C300 yet, actually going to work on it some more now.

 

Finished the install today (except for the bazooka straps) and updated the thread above.

 

im about to purchase this system

http://cgi.ebay.com/ebaymotors/KICKE...ht_4045wt_1167

i can install it the same way you did??

 

You will have to run a power wire from the battery to wherever you install the amp and you have to ground the amp as well (but you don't need to run the ground wire from the battery, just gound it somewhere close to the amp using a point on the chassis). Then, you just connect the speaker wire from the amp to the box.

However, you don't need to tap into the rear speakers to power the amp. Instead, you will need to tap into the headunit and use the supplied RCA cables (from the amp installation kit) and run them from the headunit to the amp. I didn't take my stock headunit out so I'm not sure if the C300 stock headunit has preamp outputs.

 

No. It doesn't. Unless your amp accepts high level inputs, you will need a high-to-low converter.

 

is this what i need??
http://www.amazon.com/GSI-GGLOC2-Hig.../dp/B001O0MT54

 

I never used a converter like that, but it looks like the piece you need since the stock radio doesn't have preamp outputs.

 

thats the converter i need. i called a buddy of mine who runs a shop and he said thats it. all i do is run the wires from the speaker to that n run the RCA cables from the converter to the amp and everything will work find. Thanks again for the DYI. Im going to be buying a kicker L7 ether in 12" or 15". Still don't know what size. Any suggestions??

 

Cool and you're welcome. The 12" should be good enough i think. Good luck with the install.

 

I would go with the 12" L7 if you want Kicker. The 15's will kill you unless you are into extremely overwhelming bass especially since you are not upgrading and amplifying your mids and highs.

 

lewylou, great DIY, thanks for sharing! One question, you said you cut the wires to the rear speakers and butt connected the new wires for the high level inputs. The part I don't understand is how did you tie the rear speakers back into the wiring? Did you just strip all three ends and splice them together? Could wire taps be used for this purpose as well?

 

Well, I just cut each speaker wire and stripped the covers off the ends. Then, on one end, I twisted the oem wire with the new high level wire and crimped that end onto one end of the butt connecter. The other end of the oem wire was crimped onto the other end of the butt connector.

Yes, I'm sure you can use wire taps as well, but I found that using butt connectors was the easiest and fastest way. Bazooka actually provides butt connectors with their amplified bazookas.

 

Got it, thanks!

 

my only current prob with my system is my bass hits hard and i think its rattling the tools in the tool kit and that box is a PITA to get out -___- it only happens when the truck is closed and i padded up the license plates to i know its not that. im waiting for the day to fix this problem x=

 

what the heck does LEDs has anything to do with subwoofer install?

 

Why run the power cable all the way from the battery when you have loads of power available in the trunk?, just pop off the right cover in the boot and youll find the rear SAM module, it is powered with at least 30A worth of +12V

 

I think (actually I'm pretty sure I know) that Black_Benz is Blueacc333, who has come back to try and continue selling his products again after being banned. He's already been reported.