Retrofit Retrofit
Car: Mercedes-Benz | CLK | W209 | Avantgarde | Coupe
Engine: CDi | 0 | Inline 5 | (170 BHP) | Turbocharged | Diesel

COMAND 2.0 Retrofit

This guide covers the retrofit of COMAND Satellite Navigation in the pre-facelift W209 CLK. For reference, my car was a 2003 CLK C270CDi with the Audio 20 headunit and a CD changer, which can be retained when fitting the COMAND unit.


The COMAND unit is entirely self-contained except for the GPS antenna, and due to this is very easy to retrofit, unlike in some vehicles where additional components are located in the boot.

Second-hand COMAND units are readily available on eBay (often from Lithuania), and most come with a Map disc and GPS antenna. At the time of writing the average price was £500 including delivery.

Technical background



There are small wiring differences between the COMAND and the non-navigation head units, as follows:

Standard head unit connectors

Connector Function
A Power
B Speakers
C Mercedes-Benz special connector (CD power, CAN bus etc)
D2B D2B fibre Optic
D UHF Antenna
F Diversity Antenna connection (Audio-30 etc.)

COMAND connectors

Connector Function
A Power
B Speakers
D2B D2B fibre Optic
D UHF Antenna
F Diversity Antenna (small coax connector)
E GPS Antenna (square grey coax HRS connector)
C1 Mercedes Benz 18-way high density connector (control signals)
C2 Mercedes Benz 8-way high density connector (TV RGB, CD power)

Changes required


The important changes are the wires from the existing C connector are split into C1 and C2 for the COMAND (right - plugs in top row).

The COMAND unit will work without these wires but will turn off after 1 hour, will not illuminate at night and will not power an external CD Changer.

The 5 connections in the C connector are:

C Pin COMAND Wire colour ID Function
1 C2 Pin 9 Brown (1 of a twisted pair) Interior CAN Bus Low Illumination on signal plus more
2 C2 Pin 8 Brown/Red (1 of a twisted pair) Interior CAN Bus High Illumination on signal plus more
4 C2 Pin 10 Blue/Black D2B Wakeup Power on signal for Fibre-Optic components
5 C1 Pin 6 Red/Blue CD Changer + +12v power
6 C1 Pin 5 Brown CD Changer - -12v power

Parts required


Help is at hand in the form of an OEM retrofit harness (left), there is also an auxiliary in socket available and it makes sense to fit this at the same time. The parts required for the retrofit are:

The Retrofit


The first step is to remove the existing Audio unit. This is achieved after the gear selection surround trim and the front fascia surrounding the radio and climate controls (right) are removed. This is in fact, very easy. Click for the W203 workshop guide and again for the for the W209 workshop guide .

The existing audio unit is held in by 2 Torx screws, and in my case, I had a single DIN sized oddments tray under the audio 20 which must also be removed to accommodate the double DIN COMAND.


The retrofit loom is designed to run to the CAN bus distributor in the passenger foot well, and to get to this some extra trim has to be removed. To save time I made the decision to cut off the existing car loom C connector, trim the wires on the retrofit loom and solder it in place of the C connector (left).

Pay close attention to wire colours; CD- and CAN Low are both Brown. The CAN Low wire forms part of a twisted pair so it should be easy enough to remove some extra loom tape and figure out which is which, should you get mixed up.


The next step is to install the GPS antenna (right).

Mercedes locate the OEM antenna on the rear shelf, between the speakers. There is no need to go to the trouble of locating the antenna here, most modern antennas will work equally well underneath a plastic dashboard. I mounted my antenna on the roof of the radio 'cage', above the upper switch panel (hazard warning lights and heated seat buttons etc.).


If you ordered the aux-in loom, plug the white connector to the white connector on he COMAND loom and thread the opposite end down the side of the centre console and out into the passenger foot well, I found a coat hangar was useful for this. Now follow my aux input guide and return here once finished.

Next, plug in the COMAND and then use the two new self-threading screws (A001 984 64 29) to mount it in place of the old head unit and tray, the lower screws may be hard to turn in at first because nothing was mounted in these holes before. At this point turn on the unit to ensure it functions as expected (left).

If all is OK, refit all of the trim you removed at the start of the process. Note that when turning on the unit for the first time, I noted a 15 minute delay before the navigation part of the unit became operational.

Initial Setup

Navigate to the setup menu on COMAND and ensure your correct wheel/tyre size combination is selected, this will ensure the unit tracks movement accurately:

"Ensure you have a map disk in the COMAND unit then press the NAVI key, then select Settings menu, then Calibration. Select new or used tyres and enter the tyre size of one of the rear tyres, holding down the right hand rotary know for a few seconds to enter the new values."

Taken from


A final, optional, step is to take your vehicle to a Mercedes dealer to have the unit programmed to suit your car, for example the seat material type is programmed which changes the Audio DSP settings.

My car did not require coding for the COMAND to work, however doing so would open up an additional navigation display and menu in the instrument cluster.

© Mark Stewart, Tuesday 25th November 2008
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