This tutorial will show you how to install an aftermarket Head Unit with Navigation and Backup Camera into a 2006 Mercedes ML350 with the Harman Kardon sound system. This tutorial is specific to this Head Unit from Seicane, however, some aspects will be similar to installation of any generic Head Unit and amplifier. I chose this Head Unit because it looks factory, has big touchscreen for Navigation, has hands-free bluetooth integration and iPod/iPhone support. In addition to the Head Unit, I had to install an aftermarket amplifier (Alpine MRX-V70) and an aftermarket backup camera that I bought off of E-Bay. You can read how to install the backup camera here.
What You Will Need
You will need some basic tools, supplies and of course the Head Unit and Amplifier.
- Head Unit – I bought this Head Unit from Seicane. The price was good at only $510 and it was shipped quickly. There are other units out there that are similar or may even be the same unit. I preferred dealing with a reseller rather than buying it off of e-bay.
- Amplifier – I needed a new amplifier as my Mercedes ML350 had the Harman Kardon sound system, which means that it used fiber optics for the signal and the built in amplifier would not work. I chose an Alpine MRX-V70 for its compact size, it has four channels plus a subwoofer out and can handle 2 ohm speakers. I bought if from Amazon.
- Amplifier Wiring Kit – You will need this to wire the power and ground for the amplifier. I bought a cheap kit off of Amazon.
- RCA Cables – You will need these to connect the Head Unit to the Amplifier. I used two cables with left and right connections and one for the sub.
- Fakra to SMA Adapter – This Fakra SMB “A” Coding male to SMA male adapter will allow you to use the built in GPS antenna instead of the one that comes with the new Head Unit. I bought it off of e-bay for $6.00. Here is the listing.
- Assorted Wiring Connectors – I purchased a kit with multiple connectors from Wal-Mart. These were used for connecting the speaker wires to the amp.
- Assorted Screw Drivers – You will need a phillips head screwdriver as well as a torx bit screwdriver for removing removing the head unit from the dash. I just used a screwdriver with interchangeable bits as this was the simplest way to go. If you need some inexpensive tools, I recommend Harbor Freight Tools, their tools may not be the highest end, but if you do not use them often, it may be the best choice for you cost wise.
- Socket Set – You will need a ratchet and socket set to remove the nuts holding the seat and amp in.
- E-Socket – This is a special socket that you will need to remove the bolts holding the driver’s seat down. I bought my set at Harbor Freight tools.
- Large Torx Socket – You will need this to remove the seat belt from the Driver’s front seat. I think it was a T45 but I am not sure.
- Wire Stripper – You will need this to strip the power, ground and speaker wires when connecting the amplifier and head unit.
- Electrical Tape – You will need this to wrap up the electrical connections and wires.
- Multimeter – You will need this to verify which wires have power and which are ground.
The Head Unit
When we decided to buy our Mercedes ML350, we knew going in that we would add GPS, a rearview camera and hands-free phone integration. I looked into adding the factory GPS as well as factory phone integration. Both were available on e-bay, but even a used GPS part was expensive. In order to add navigation, I would have to buy the GPS DVD part and add it to the existing head unit, this was $500 for a used one. The phone integration was almost $1,000 and from what I read was not that great and I would still need to add a backup camera. So, after $1,500 plus, I would have a DVD based navigation system from 2006 and weak phone integration. This would not do.
Therefore, I did some research online, surfed the Mercedes forums at BenzWorld.org and MBWorld.org, both of which provided a ton of useful information and help. Because of the unique shape of the factory head unit, I could not go with a standard 2-Din aftermarket head unit. Which was fine with me as I prefer the look of a factory system. After a lot of reading and searching I decided on a new GPS head unit from Seicane.com. It looks factory and has all the features I wanted including a modern GPS, touch-screen, iPod integration, hands-free Bluetooth calling, back-up camera integration and more. You can even it get it with Digital TV input if you want.
Here is the GPS Head Unit from Seicane all unboxed, showing everything that comes with the Head Unit. The Head Unit comes with two cables bundles, one if you are using the audio outs or have a non-fiber optic system as well as a long bundle of cables which allow the unit to connect to the speaker wires directly so that the unit powers the speakers instead of an amp. There is also a GPS antenna, USB input cable, iPod cable, antenna adapter and a ton of RCA input/output cables.
I chose the Alpine MRX-V70 for its compact size, good power output with 5 channels and its ability to handle 2 ohm speakers. One of the biggest factors was to get a compact amp that still had a large power output. This one fit the bill. Because the amp is under the drivers seat, it does not get a lot of air movement, so it was critical to find a high powered amp. This allows the amp to be more efficient at normal audio levels and thus not overheat. After I had everything installed but before putting the seat back in, I ran the new stereo at twice the volume we would listen at, to see if the amp got hot. It never did, therefore I was comfortable with it being buried under the driver’s seat.
Remove the Factory Head Unit
Removing the factory Head Unit is easy. I did not take any pictures of this process but found some at www.mercupgrades.com. Here are the instructions from that site.
Firstly remove the whole panel below the COMAND unit with the aircon and other buttons – this is done by opening the ash-tray, and putting 2 fingers below the panel on each side, pushing upward to release the latches and pulling hard. Here is a picture showing where you are pulling once the ashtray is open.
You will then see two silver bars below the audio head unit – remove the 2 TORX screws, then slide the silver bars downward, and then you can remove the head unit. Here is a picture with the screws removed and the locking bars moved downward.
Now just slide the head unit out and disconnect the cables.
Remove the Driver’s Front Seat
Next, you have to remove the Driver’s side front seat. You should disconnect the battery before you disconnect the wiring from under the seat, because if you don’t, the car will give an SRS (Airbag) error, since you have to unplug the airbag in the seat in order to remove the seat from the car. I did not do this and was forced to take it to a mechanic to clear the code. I was fortunate that I am friends with a mechanic, so it was free.
First, you will need to remove the plastic trim pieces from the four corners of the seat track. These just pop off, but be sure not to break the tabs. Then remove the bolts from the front two corners. You will need a special E socket to remove the bolts.
Next, move the power seat all the way forward and remove the rear trim and bolts that hold the seat in place.
Now, before you can pull the seat out of the car, you will need to unplug the cables under the seat that connect the airbag and power seats. These are easy to access from the front of the seat. Next, you will need to unbolt the seat belt from seat. This is attached under a easy to remove trim piece and uses a large torx bit. Then you should be able to simply remove the seat from the car.
Access the Amplifier
Once the seat is out, you will need to pull back the carpet in order to gain access to the space under the seat where the factory HK Amplifier is installed. This is where I decided to install the new amplifier and is where the wires for all the speakers terminate.
Pull back the carpet towards the rear of the car. It is tough to bend but not impossible. You will need to remove the trim piece from the door sill first.
Next, we will need to remove the air venting and the plastic shield that covers everything. The venting is held on with a small plastic rivet that is easy to remove. Then the tough part. The plastic cover is held in with some nuts that come out pretty easily, except for one that is under the door trim. I did not want to completely remove all of the door trim as it looked very difficult to remove. I ended up prying the trim back so that I could get the socket under it to remove the last bolt that was holding the plastic panel in place. Not the easiest process but it worked. Once removed, you will see the factory amplifier and the wires that go to it.
Remove the Factory Amplifier
Removing the factory amplifier is pretty easy, just unbolt it and disconnect the cables that are attached to it. Once you have the amplifier out, take a look at the wires that attached to it. I cut the wires as close to the factory connector as I could to give me as much wire to work with as possible.
I could not find a wiring diagram specifically for my ML350, so I used the old trick of using a battery to power the individual wires to figure out which wires went to each speaker. I had help, while I connected the wires to the battery my assistant would determine which speaker made the sound and also looked at the movement of the cone to determine the correct polarity. I somehow lost my notes on the wire colors, but if I remember correctly, it seemed that all of the positive wires were in one row on the connector and all of the negative were on the other row. There were two sets of wires for the front door speakers, two sets for the rear speakers as well as wires for the center channel and the subwoofer, which is a dual coil. I wired all of the front speakers together on each side and added the center channel to the left side as well. I wired the rear door speakers and rear surround channels together as well. And lastly, the two subwoofer wires. Many will argue whether this was the best way to do it, but everything works, sounds fantastic and the amp never got hot while blasting the stereo at high volume, much higher than we would ever listen at. However, I did replace the factory subwoofer, as I think the new amp was too powerful for it and it smelled like it was burning. I used a single coil subwoofer for the replacement.
Installing the New Amp
I first ran power from the battery to the amp by feeding the power cable up behind the head unit, as this seemed much easier than trying to remove the carpet from the rear. However, this is not an ideal way to do it. After I had everything up an running I noticed a hissing sound that turned out to be most likely caused by the power cable running next to the RCA cables from the head unit. I was able to fix the hiss by grounding the head unit and the ground side of the RCA cables to the chassis. So, I would suggest that you not run the power cable the way I did.
Here, you will see the power cable, ground cable and a cable I ran to activate the amplifier. I cleared away the paint and bolted the ground to an existing stud in the amp area.
The other end of the blue power cable was connected to the battery with an in-line fuse. Do not use the power wire that the factory amp used, it will not be sufficient to power the new amp.
Here, you can see the new amp installed in the space where the old amp was. I used the screws that came with the amp to screw it directly to the metal in the floor. I ran the stereo at high volume for a while and the amp never got hot. Therefore, I did not have any concerns with it overheating being installed under the seat this way. I taped off the power cable from the old amp to ensure no shorts. Running the RCA cables from the had unit under the carpet was not too difficult, I just used a single wire first then taped the cables to it and pulled them through.
Just a quick note on reassembling the car. I could not get the plastic cover to install back under the door trim for the life of me. So I just trimmed it off and everything went back with no problem. Installation is just the reverse of the disassembly. If you want to power it all up before reinstalling the seat, be sure to plug the seat back in before the battery is reconnected to avoid the SRS light.
I was able to stop the hissing by connecting the grounds from the RCA cables to the chassis ground. Here you can see how I did it.
Connecting the Head Unit
I did not take any pictures of the installation of the head unit, sorry. But I can tell you it is very simple. Connect the provided cables to the RCA cables to the Amp. Connect the CAN connector to the harness, connect the Amp signal cable, the Reverse trigger together and that is about it. I would suggest that you tape the connections together with some electrical tape so that they do not separate while you are position the head unit and all the wires into place. I used a Fakra connector adapter to connect the GPS antenna installed in the ML350, so need to run an extra antenna. You will need an antenna splitter that connects under the driver’s side rear seat. I bought mine off of e-bay for $30. Here it is connected and in place.
iPod or iPhone Connector
I was able to connect my daughter’s iPhone 5S to the iPod connector from the head unit. I did have to use a couple of adapters to get it to work. I will post a guide on how I did it and how I was able to mount it in the ashtray so that it holds the iPhone 5S while charging and listening to the music from the iPhone.