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

Facelift Centre console upgrade and Audio 20


I really dislike the pre-facelift centre console right; the switch gear, head units and oddment tray really look cheap and dated and serve to lower the overall quality of the interior. This is especially so when interior trim finishers are silver, such as in my CLK, which draw attention to the buttons.
The post 2004 switch gear looks infinitely better in terms of design and quality, and much more at home in the interior. Facelift head units are also of improved quality and the upgrade route to COMAND APS is available, and this was in fact my primary motivator for upgrading after being hugely disappointed with a recent COMAND 2.0 retrofit.

At the time of writing there seems to be much misconception of whether a facelift console retrofit was possible in a pre-facelift car, the misconception is centered around the MOST Fibre equipped head units, but after reading technical documentation I decided this upgrade was straight-forward.



MOST and D2B are both kinds of Fibre Optic Bus networks for connecting infotainment modules within the car, for example; Phone, DSP Amplifiers, Voice Control, TV Tuner etc.


D2B is a Mercedes-Benz propriety bus that was used in the pre-facelift W203 C and W209 CLK (and rest of the range). It is typically used to connect the Head unit and CD changer, and phone where fitted. D2B is a bus network (a ring topology) ad typically if one device in the ring fails, data can not be transmitted to the next device and so the entire system fails.

D2B devices are powered up when required with a 'wake-up' signal in order to conserve battery charge when not in use. The D2B 'wake-up' signal is provided by the head unit and is simply a switched 12v. Wires are Blue/Black and are usually joined at a junction in the left-hand side foot well.

The D2B Fires are orange in colour and are connected in physical pairs; one end terminates with a red filter, and the other is clear.


Media Orientated Systems Transport, like D2B, is a Fibre optic ring (although may be star) network for automotive infotainment devices. The system was first used by BMW in the 7 series and is also used, and developed, by Ford, BMW, DaimlerChrysler, and GM.

MOST networks require a timing controller, or bus 'master', which synchronises the rest of the devices on the ring with timing signals . Mercedes often incorporate the bus master in a box along with the Audio amplifier or radio tuner and call it the Audio Gateway Unit or AGW for short. In the case of the W203/W209 which were never launched with MOST, Mercedes launched MOST systems with the AGW incorporated into the head unit. This configuration is unique to the C/CLK and my assumption is that it was a decision made to reduce complexity and cost when making the switch to producing MOST equipped vehicles. The E-Class, for example uses a separate AGW box which is mounted in the boot.

Note: CAN BUS Do not confuse D2B or MOST with CAN. Controller Area Network is an electrical based bus for control devices i.e. windows, locks instruments etc. and is not related to the feasibility of this upgrade.

Now that we know the MOST AGW is integrated on the C/CLK, upgrading the centre console becomes a process that can be split in to two main areas; electronics and trim.

Electronics | Climate Control Panel

The climate controls remain identically wired between pre and post-facelift vehicles, so fitting is 'plug 'n' play'. I chose to upgrade to Luxury Climate Control whilst fitting the facelift console. A normalisation of the air vents must be performed after fitting regardless of what level of control unit is fitted.

Please see the Luxury Climate Control Retrofit article for details of how to identify pre and post-facelift Climate Control units, how to upgrade to Luxury version, and how to normalise the vents.

Electronics | Head Unit

The range of head units has been improved for face lifted vehicles, please see the table below for a brief comparison.

Head unit options

Pre-Facelift Model Facelift Model Description
Audio 10 Audio 20 Basic Audio
Audio 30 APS Audio 50 APS Basic Navigation
COMAND 2.0 COMAND APS Large-screen Navigation


Face lifted cars adopted the ISO standard Quadlock connector and this must be retrofitted in order to fit one of the face-lifted head units.



Facelift Centre console upgrade and Audio 20

The 'Quadlock' right is a large connector which incorporates the ISO standard audio & power connectors as used on aftermarket head units. It connects the head unit to the cars electronics.

The connector typically houses a speaker connector (Cream) and a data/power connector (Black), but has provision for 2 'Aux' cable connectors (Blue, Green) and a Fire Optic connection (Black with circles) where required.

The majority of modern vehicles are now equipped with a Quadlock connector and pin positions are common, being specified by the ISO.

The good thing about the Quadlock connector is that pin positions remain the same whether upgrading to COMAND-APS or a non-navigation head unit, this was not the case with the pre-facelift COMAND 2.0.

The steps required install the Quadlock differ slightly for COMAND 2.0 equipped and non-navigation vehicles, due to connector differences which are fully explained in the COMAND 2.0 retrofit guide however, the following sections will provide all the information required to update should you not wish to read this and understand the differences.

Quadlock wiring - Upgrading from Audio 10

C Pin Quadlock Pin Function Wire Colour
D2B Audio 10 | C Connector
1 11 CAN Bus High Brown/Red
2 9 CAN Bus Low Brown
4 16 D2B Wakeup Blue/Black
5 15 Terminal 30 (CD Changer +) Red/Blue
6 12 Terminal 31 (CD Changer -) Brown
D2B Audio 10 | B Connector
1 1 Right Rear Speaker + White
2 5 Right Rear Speaker - Brown/White
3 2 Right Front Speaker + Orange
4 6 Right Front Speaker - Brown/Orange
5 3 Left Front Speaker + Green
6 7 Left Front Speaker - Brown/Green
7 4 Left Rear Speaker + Pink
8 8 Left Rear Speaker - Brown/Pink
D2B Audio 10 | A Connector
2 NC* Diagnostics Green/Black
3 10 Mute Yellow/Black
4 15 Terminal 30 (+) Red/Blue
5 13 Antenna Supply Black
8 12 Terminal 31 (-) Brown

Quadlock wiring - Upgrading from COMAND 2.0

C Pin Quadlock Pin Function Wire Colour
D2B COMAND 2.0 | C1 Connector
6 15 Terminal 30 (CD Changer +) Red/Blue
5 12 Terminal 31 (CD Changer -) Brown
D2B COMAND 2.0 | C2 Connector
8 9 CAN Bus Low Brown
9 11 CAN Bus High Brown/Red
10 16 D2B Wake up Blue/Black
D2B COMAND 2.0 | B Connector
1 1 Right Rear + White
2 5 Right Rear - Brown/White
3 2 Right Front + Orange
4 6 Right Front - Brown/Orange
5 3 Left Front + Green
6 7 Left Front - Brown/Green
7 4 Left Rear + Pink
8 8 Left Rear - Brown/Pink
D2B COMAND 2.0 | A Connector
2 NC* Diagnostics Green/Black
3 10 Mute Yellow/Black
4 15 Terminal 30 (+) Red/Blue
5 13 Antenna Supply Black
8 12 Terminal 31 (-) Brown

Obtaining Quadlock

Facelift Centre console upgrade and Audio 20

My Mercedes parts department couldn't locate a Quadlock connector in the parts system, but this is not to say there isn't one available. In the end I settled for a Parrot (aftermarket Bluetooth system) mute lead for a Facelift C/CLK right and removed the wires from it.

For reference, the smaller auxiliary connectors are available separately Aux 1, Aux 2.

Fitting the Quadlock

Fortunately, the Quadlock power and speaker connectors share the same type of pin as those found in the pre-facelift wiring connectors, which means moving the majority of wires from old A,B,C connectors to the Quadlock can be relatively pain-free. There are special tools in existence to release the pins from their housing; these are referred to as 'Pin Extraction Tools'. If you intend to regularly work on your car electronics then I recommend spending £85 to get this.

Facelift Centre console upgrade and Audio 20

Mercedes themselves sell a tool which looks like a screwdriver with a range of screw-on tips (Mercedes refer to them as 'blades') to suit different electrical connectors. The part number for the tool is W220 589 01 99 54 and the correct blade for the large Quadlock pins is W220 589 01 99 50. The tool costs around £40 with the blade, but saves considerable time and negates the need for soldering.

The tool is inserted from the non-cable side of the connector, along recesses alongside each pin. Once the tool is pushed home simply pull the relative wire from the rear of the connector. Take care when handling the removed pin to ensure its locating barbs don't get squashed flat; these can be teased back out with a razor blade/scalpel or similar.

Accessories: CD Changer, Bluetooth etc,

Please remember that your old D2B based options will not work with the facelift head units. The retrofitting of MOST based options is not covered in this article.

Fire Optics

As explained at the beginning of this article, MOST uses a ring network which fails if the physical ring is broken. Head units are programmed on the Mercedes 'STAR' interface computer with the options they are fitted with, for example Bluetooth module and CD Changer. If you are purchasing a second-hand radio/Nav unit then it's impossible to identify this coding from serial numbers, so I recommend buying a Fibre Optic lead to complete the ring network and prevent an error; if a unit is coded for say, a CD changer, then it will not turn on without a complete fibre ring. It will however function with a complete ring even if the CD Changer is not present!

D2B Fibre optics cannot be re-used here, but the MOST type Optics are very reasonably priced. I used Fibre optic A211 540 31 32 (the last 2 digits of the part number here denote length and many options are available) to create a small loop; the fibre comes with 1 connector pre attached, and what I did was to loop the unattached end of the fibre round and install it in the same connector.

Electronics | Upper Control Panel

The 'Upper Control Panel', referred here on in as UCP, is the bank of switches above the Radio. The unit is connected by 4 wires; Can Hi, Can Lo, + and -, and additionally a heated seat plug if this option is fitted. Upon studying the Mercedes wiring diagrams I noted that the same diagram was used for pre-facelift and facelift cars, and so I tested out a Facelift UCP in my own car; everything worked as expected!

NOTE: Function buttons you may purchase an UCP with buttons for options not fitted to your vehicle; the extra buttons will illuminate but when pressed will not cause any errors.

Convertibles, and 'Distronic' or 'Keyless Go' equipped vehicles

The gear lever surround is classed as the 'Lower Control Panel' and typically houses the Distronic display and Convertible roof switch. The LCP connects to the UCP via a second set of 4 wires; again, Can Hi, Can Lo, + and -. I did not research the position of the LCP wires on the rear of the UCP. If you are stuck here please leave a comment at the bottom of the article and I'll revisit the Mercedes wiring diagrams.

Wiring the facelift UCP

Facelift Centre console upgrade and Audio 20 Facelift Centre console upgrade and Audio 20

The correct set of pins lie in the central 6 pin connector, and whilst the wires to connect the facelift remain unchanged the connector itself doesn't. I tried in vein to locate a breakers yard who would sell the connector and wires separately, so in the end I had to settle for another means of connection.

The images to the right show the correct facelift connectors. The far right image shows the UCP power/CAN wires, and the 3 pin connector is for optional heated seats.


The pin sizes on the facelift UCP are pretty standard din single pins as found in most computers and electronics devices. I used the connector from the end of a PC Floppy drive power supply lead, cut the wires and soldered to the Mercedes loom.

Whilst the pre-facelift pins are identical, the actual pin sockets crimped on the end of the wires differ slightly and cannot be used in the facelift UCP.

Pin Function Wire Colour
UCP Central connector (6 Pin)
1 Terminal 31 (-) Brown
2 Terminal 30 (+) Red/Blue
3 CAN Low (In Twisted Pair) Brown
4 CAN High(In Twisted Pair) Brown/Red
5 N/C N/C
6 N/C N/C

NOTE: The table above lists the correct Mercedes-Benz wire colours. The wire colours shown in the photo (Above Right) differ as I used a PC lead to make the connection.

Trim | Process overview


Many manufacturers mount the radio and climate controls in a central cage (right), and Mercedes are no different. The correct facelift 'cage' must be obtained in order to fit the new radio, UCP and climate panel to the dashboard. The part number for the CLK is MA209 689 01 16 .

Despite being a relatively small part, fitting the replacement cage unfortunately involves removal of the following (in order):

The actual fitting of the facelift cage is the exact reversal of the above steps, and be completed either before or after the wiring modifications have been performed.


I did notice that it was possible to take a short cut and leave the instrument cluster & drivers side lower dashboard panel in place (left), and carefully hold the dashboard panel out of the way whilst removing the radio cage. If you decide to take this route then please take great caution to ensure the dashboard panel does not crease.

Trim | Process overview

Special Tools

There are two special tools required if you choose to remove the driver size lower dashboard panel (recommended); one to remove the instrument cluster, and one to remove the bezel around the ignition switch. These are both obtained from Mercedes and are reasonably priced:


The removal of the trim pieces falls outside the scope of this article. I recommend obtaining a copy of the Mercedes WIS net (EWA) workshop DVD's; ask on forums or search eBay.

Trim | UCP and Climate surround

The trim surrounding the UCP and Climate panel is fastened by T25 Torx screws, and so can be removed and swapped with a trim which matches the rest of your car; I found the textured Aluminium trim on eBay which matched the trim in my car. Black Ash would have been the ultimate, but is ultra-rare!

Completed project

Here are pictures of my 2003 CLK with the facelift centre console and Luxury Climate Control fitted.

w209faceliftconsole w209faceliftconsole w209faceliftconsole
© Mark Stewart, Tuesday 25th November 2008
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