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Mercedes SL / Dension IceLink install

The Dension IceLink 500 is an interface between factory head units and an ipod, along with other sources. It enables playing of the ipod in the car, with the high quality sound, and some control of the ipod itself from the head unit. In essence it does this by emulating a CD changer.

My 2004 SL55 has the Mercedes COMAND unit installed, and I was reluctant to replace it. It’s well integrated into the car and although the GPS is pretty clunky, it does at least work. The IceLink seemed like a good compromise of cost, hassle and quality.

Now that I have been using the IceLink for a few months I can report that it works perfectly, though there are some unavoidable quirks due to the limitations of the head unit. For Mercedes owners with COMAND and D2B or MOST interfaces, it’s the easiest way to get lossless ipod control. This article explains how I completed my installation. Follow at your own risk.

Brief overview of IceLink

The IceLink unit emulates a CD changer. Newer Mercedes cars (post 1999 or 2000) have a fiber optic network installed known as D2B. Around 2005 this changed to MOST, which has slightly different fiber optic connectors and possibly a different protocol. You need to order the right one for your car, though they seem functionally identical in the context of this installation. My car uses D2B.

The fiber optic network carries all signals around the car that relate to electronics of the navigation system, music playback, CD changer, Telephone and instrument panel. It’s a pretty clever way of reducing the size and complexity of the wiring loom. Each unit has optical in and out, usually integrated into one connector. The units are daisy chained to each other in a ring. Thus audio from the CD changer travels to the head unit via the optic network, and is possibly passed within the telephone interface on the way. The IceLink slots into the network, becoming an additional unit, and it functionally replaces the CD changer. A switch toggles between using the CD changer and IceLink.

IceLink 500 connectors

The IceLink is intended to be inserted behind the head unit, and comes with a set of loom connectors (3 male, 3 female) that insert it into the signals at the head unit without cutting any wires, together with an equivalent setup for the fiber optic, plus of course connectors for the ipod itself, the control switch, RCA inputs etc. Looking at the loom connectors and the size of the icelink (approx like a pocket paperback) I was concerned about the amount of space behind the head unit, in the dash. The connectors tap into only 4 signals in the loom. Since the audio data is carried around on the fiber optic network, you can insert the icelink anywhere that has a fiber optic connector. The only wiring you need are the above mentioned 4: ground, 12v unswitched, 12v switched and a signal named ‘wake’ that is related to the fiber optic system (devices on the network save power by going into sleep mode until they detect a signal on ‘wake’. The same signal is electrically shared by all units, so you can also tap into this anywhere)

Choosing a location

Some readers might be concerned about self-install in an expensive car like the SL (or any Mercedes). I actually prefer self install of electronics because I’m nerdy, comfortable with a soldering iron and volt meter, and perhaps crucially, I subscribed to the shop manuals at http://www.alldatadiy.com. These manuals are a little hard to navigate and are aimed at experienced mechanics, but it offers the key information such as removing interior panels and defining wire colors.

The SL has two storage bins behind the seats which are pretty useless because they’re so small. One of them contains the CD changer, so my initial thought was to tap into the needed signals at the CD changer itself, and place the icelink inside storage bin. I started to disassemble the bin to access the bottom connectors on the CD changer, but found the job pretty heavy going. Even with the excellent information at alldatadiy.com, I began to rethink my idea of using the storage bay.

While attempting to expose the CD changer, I removed the panel on top of the transmission tunnel, directly behind the center armrest/storage bin. Buried in there I found a unit connected to the D2B fiber optic bus, and determined it’s the cell phone hands-free adapter (pipes the call into the stereo speakers, muting the music, and picks up speech from the microphone). Given how easily this can be exposed, I switched my attention from the CD changer. I also realized this would enable placing the ipod inside the center storage bin, which turned out to be exactly the right place. You’re likely to use the ipod itself to select music, so placing it in the passenger glove box would be a huge inconvenience while driving, and is about the only possible place if you mount the IceLink in the dashboard.

The area behind the center storage bin has a space that looks ideal for hiding the main IceLink unit. Sadly it’s fractionally too small. After some experimentation, I found the best place is in the right storage bin (when facing the front of the car). This bin has a panel in the bottom that exposes the main fuse bank. It therefore provides an easy way to route the fiber optic cable from the splice into the phone unit, and to similarly route the ipod cable. Finally I decided to hide the IceLink/CD change switch behind the fuse access cover, since I’m very rarely going to operate it. My IceLink install therefore is almost invisible, yet still accessible from within the passenger compartment.

Remove the transmission tunnel panel, behind the center storage bin

There are two screws (torx, like just about every screw and bolt in the car) inside the large center console bin, in the rear panel. Once removed the panel behind can be easily forced out by lifting the front edge first. The photo below shows the panel removed. I’m really sorry for the dreadful quality; my digital camera was MIA so I was stuck with the camera built into my phone.

Center panel removed, fuse box cover removed

The left side shows the center console storage bin with the lid closed. The green thing is a torx screwdriver set. The right side shows, top to bottom:

• The right rear storage bin, with the lid open and the bottom panel removed, showing the fuses.
• The components exposed by removing the panel. The yellow wires are in fact pneumatic tubes that power the locks on the storage bins. The orange wires lead into the cellphone control and are in fact the D2B fiber optics. We’re going to tap into this and feed the D2B into the IceLink, and then back to the phone unit.
• At the bottom is the left storage bin, open, showing the CD changer. Ignore it.

Modify harness, tap into power source, tap into D2B optic

A large harness comes with the IceLink, comprising male and female for all 3 connectors, plus a small plus that feeds power to the IceLink. I found this very cumbersome when all it’s doing is tapping into power plus the D2B wake signal. Since I located the IceLink away from the head unit, the huge pass-through harness was unnecessary, so I made the decision to cut the IceLink power cable out and feed power in directly from somewhere else. I actually saved the harness, and by a strange twist of fate I ended up using half of it to install a Pioneer Avid D3 into my CLK320.

The IceLink normally draws power from the head unit, but I figured that any device on the D2B bus will have the wake signal, plus the necessary power. The cell phone adapter is just such a device, and it’s exposed under the above shown panel. There’s a 15pin D connector on the back that can be unplugged in the tight quarters. By probing around with a voltmeter, plus consulting my subscription to alldatadiy.com , I found the power cables plus wake and of course ground on this connector. I tapped into the wires per below and soldered in the IceLink power cable salvaged from the supplied harness. I tend to use solder connections because I find them more reliable, plus there’s not much space back there for the crimp style tap-in. With planning they’d probably be OK, however.

• BN* (Brown) = Ground on phone unit, connect to Black on IceLink connector
• BUBK* (Blue with Black stripe) = Wakeup on phone unit, connect to purple on IceLink
• RDBK* (Red with black stripe) = Power on phone, connect to Red and also Blue cable (unswitched power).

*notations used in the shop manuals I accessed through alldatadiy.com.

The cell phone adapter is also the ideal spot to tap into the D2B bus, using the supplied tap fiber cable. The only catch is the angle needed to bend the cable to get into the cell phone unit, and to prevent the cable fouling the center console storage bin mechanism. Great care must be taken to prevent bending the fiber optic too tight.

Feed the cables under the right console, bringing them out through the fuse box

With the fuse box access removed in the right storage bin, it’s easy to bring the cables under and then out of the fuse access. In the above photo you’ll see the interior panel behind the passenger door has been removed. Save that step for later, after confirming everything works.

Plug in the IceLink, check it works.

Plug in the power cable, the optic, the ipod/CD changer toggle switch and of course the ipod. Leaving the IceLink floating around in the storage bin (be gentle with the optic cable) you can switch on the ignition and test the unit.

At this point for me nothing worked, though I was fairly sure the IceLink was functioning because the CD changer no longer played. I reread the manuals and found my second generation iPod was not supported. Aaaarrggh. I was willing to buy a new ipod, but wanted to prove the IceLink was working first, so I needed a compatible music source. Remembering the USB connector built in, I noted from the manual how to play music stored on a thumb drive. I grabbed one from my laptop bag, plugged it in and found the IceLink played the MP3 files on there perfectly, and the head unit permitted song skip and rewind. Having therefore concluded everything worked, it was time to find a permanent home the the IceLink, the toggle switch and the ipod cable. I also ordered a new ipod, and even found a use for my old when I installed a Pioneer AVIC D3 in my CLK320.

Mounting the IceLink

In the photo above you’ll see I have removed the right side panel, behind the passenger seat, exposing the bodywork (mid-gray colored stuff at the top of the photo) and some electrical equipment (silver box). The exposed area is the perfect place to mount the icelink. The box forming the storage bin is easy to drill, the cables are exposed through the fuse box access panel and there’s plenty of room. Removing the side panel is pretty easy:

1. Remove the cast aluminum trim panel at the top of door opening.
2. Pop off the sill cover.
3. Peel off the rear of the door seal.
4. Remove the trim panel covering the forward facing section of the storage bin, exposing a bolt that secures the side trim panel.
5. Pop off the trim panel carefully, starting at the front and working towards the back

I used some drilled metal strips to help secure the IceLink to the outside of the storage bin, fearing otherwise it could work loose and rattle around back there.

Mounting the toggle switch

It’s important to place the toggle switch in a position where you can access it, albeit occasionally. You’re only going to need it when the car goes in for service or if you want to use the CD changer. I placed the toggle switch close to the fuse access panel, underneath the storage bin bottom. This keeps all the cables hidden and yet should I need to access the toggle, I simply pop out the fuse cover and I can see it from the drivers seat. The only visible evidence is the two screws in the bottom of the bin, securing the toggle below.

Routing the ipod cable.

The ipod cable is long enough to reach from the right side of the storage bin, through the fuse box, up into the center panel and then be fed through the center storage bin hinge mechanism and into the upper compartment. This can also house the cell phone cradle, which I don’t have. It’s therefore perfect for an ipod: easy to access even while driving, free of other junk and it locks with the doors (important if you leave the car with the roof down, as I sometimes do)

There’s a trim piece in the upper bin that forms the coin holder, carries a couple of buttons, and hides the wiring for the cell phone cradle. The trim piece is secured from under the upper bin with a set of small torx screws. With this removed you’ll find it easy to drill a hole for the ipod cable that will then be hidden when the trim piece is replaced (regrettably the hole needs to be a fair size to get even the smaller end of the ipod cable through it). I then fed the ipod cable under the corner of the trim piece, cutting out a small notch.

Test everything, put it all back together

Of course you should now test everything, including driving the car and playing the ipod, to make sure you have no loose connections. I’ve had mine installed for a few months with no problems and am very happy.