First post - head unit replacement? and other questions..

edison · 08-01-2008

Hi all, this is my first post. I see the notice about introducing myself in the "Introductions" forum, but where is that forum? I must be blind

Anyways, I live in Norway and I got my 2005 SLK200 (r171) about a month ago. Been lurking on these forums ever since, besides driving it with the top down

Here in Norway cars are generally extra expensive, so this is my first non-"wreck-on-arrival" car.

Being a technocrat I have so many questions about this car, mostly non-performance-related, I am in it for the comfort... Anyways, here goes:

1. I have obtained a CAN-capable OBD2 interface which successfully shows malfunction codes, throttle position and all the basic data.. I believe this uses the "PWM" OBD2 mode, which is very basic. I understand there are many CAN buses in my car, most or all of them available in the hidden compartment under the left side door..is there a comprehensive reference of the messages passed on these buses anywhere?

For instance, where can I "sniff" the steering wheel button press messages, and how can I inject information on the main display unit via can?

2. Having bought my car second-hand, I have an "Audio 50", which is a very basic amp/CD + navigation unit. Is it true that it uses the MOST standard on my r171?

3. From what I understand it is possible to replace this "head unit" with any standard 2-DIN form factor unit. Is it possible to replace it with a "Comand"?

4. In fact, I'd like to replace the existing audio 50 with a full-fledged bare-bones computer to run Linux on it

Assuming it is possible to fit any 2DIN unit, do you guys know of a computer with a nice audio amplifier, full-colour touchscreen which fits as a head unit in the slk?

5. If any such computers exist, can I use the existing face plate with the nice original keypad, volume knob etc?

Bear with me if these are stupid questions... Just a linux/electronics geek with my first proper, lovely car and I'd like to tap into this community :-)

BTW, I simply LOVE my SLK!

**DansSlk** · 08-01-2008

Hi welcome to SLK World.

Will have a shot at your questions -

1) The SLK has 4 CAN networks, 2 LIN networks and a MOST optical network, a very basic description of the layout would be -
CAN-C - Data in front of forward firewall
CAN-B - Interior databus
CAN-D - Diagnostic databus from the OBDII connector to the CGW
Private Bus - Between EIS and EZL
Steering LIN - Steering wheel controls to SCM module
AC-BUS (LIN) - Blower and flapper control to AC control unit
MOST - Infotainment system

I'm afraid while MB use the fairly open CAN standard the data within the packets transmitted on its busses is proprietary and not released to the public so you can see the data flow but not really decipher it (you will know a packet is on the bus but its function will remain a mystery unless your prepared to sit and sniff all the packets and guess at the functions, and the busses are VERY busy).

2) Yes MOST optical data bus from the headunit to the AGW that contains the amp and the interface to the CAN-B bus.

3) To replace with a non-MB headunit (or even an MB headunit with an integrated AGW) when you have a separate AGW fitted is bloody hard BUT because you have an AGW already installed a COMAND update is plug and play (without navi).

4) I don't know of any units personally but people do make this swap and they seem to be happy with the units they pick so take a look around the site, what i would say is not many people upgrade from the Audio 50 / COMAND systems with separate AGW because all of the wiring must be moved to the back of the headunit from the footwell where the AGW is mounted.

5) Depends on how handy you are with a soldering iron i guess mate.

**UK-C200** · 08-01-2008

Welcome!! Dan has covered most of the basics.. I'd suggest you take a look at mp3car.com - it's a good resource for carputers.

I've seen a couple that looked really good (2 din touch screen), and I think they were both running Linux.

**Gabus** · 08-02-2008

Hei, og velkommen fra Søgne

08-01-2008	#1 (permalink)
edison SLK World Junior Member Join Date: Jul 2008 Posts: 1 Country: Thanks: 0 Thanked 0 Times in 0 Posts	First post - head unit replacement? and other questions.. Hi all, this is my first post. I see the notice about introducing myself in the "Introductions" forum, but where is that forum? I must be blind Anyways, I live in Norway and I got my 2005 SLK200 (r171) about a month ago. Been lurking on these forums ever since, besides driving it with the top down Here in Norway cars are generally extra expensive, so this is my first non-"wreck-on-arrival" car. Being a technocrat I have so many questions about this car, mostly non-performance-related, I am in it for the comfort... Anyways, here goes: 1. I have obtained a CAN-capable OBD2 interface which successfully shows malfunction codes, throttle position and all the basic data.. I believe this uses the "PWM" OBD2 mode, which is very basic. I understand there are many CAN buses in my car, most or all of them available in the hidden compartment under the left side door..is there a comprehensive reference of the messages passed on these buses anywhere? For instance, where can I "sniff" the steering wheel button press messages, and how can I inject information on the main display unit via can? 2. Having bought my car second-hand, I have an "Audio 50", which is a very basic amp/CD + navigation unit. Is it true that it uses the MOST standard on my r171? 3. From what I understand it is possible to replace this "head unit" with any standard 2-DIN form factor unit. Is it possible to replace it with a "Comand"? 4. In fact, I'd like to replace the existing audio 50 with a full-fledged bare-bones computer to run Linux on it Assuming it is possible to fit any 2DIN unit, do you guys know of a computer with a nice audio amplifier, full-colour touchscreen which fits as a head unit in the slk? 5. If any such computers exist, can I use the existing face plate with the nice original keypad, volume knob etc? Bear with me if these are stupid questions... Just a linux/electronics geek with my first proper, lovely car and I'd like to tap into this community :-) BTW, I simply LOVE my SLK!

08-01-2008	#2 (permalink)
DansSlk Dude Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,797 Country: Thanks: 96 Thanked 227 Times in 179 Posts	Hi welcome to SLK World. Will have a shot at your questions - 1) The SLK has 4 CAN networks, 2 LIN networks and a MOST optical network, a very basic description of the layout would be - CAN-C - Data in front of forward firewall CAN-B - Interior databus CAN-D - Diagnostic databus from the OBDII connector to the CGW Private Bus - Between EIS and EZL Steering LIN - Steering wheel controls to SCM module AC-BUS (LIN) - Blower and flapper control to AC control unit MOST - Infotainment system I'm afraid while MB use the fairly open CAN standard the data within the packets transmitted on its busses is proprietary and not released to the public so you can see the data flow but not really decipher it (you will know a packet is on the bus but its function will remain a mystery unless your prepared to sit and sniff all the packets and guess at the functions, and the busses are VERY busy). 2) Yes MOST optical data bus from the headunit to the AGW that contains the amp and the interface to the CAN-B bus. 3) To replace with a non-MB headunit (or even an MB headunit with an integrated AGW) when you have a separate AGW fitted is bloody hard BUT because you have an AGW already installed a COMAND update is plug and play (without navi). 4) I don't know of any units personally but people do make this swap and they seem to be happy with the units they pick so take a look around the site, what i would say is not many people upgrade from the Audio 50 / COMAND systems with separate AGW because all of the wiring must be moved to the back of the headunit from the footwell where the AGW is mounted. 5) Depends on how handy you are with a soldering iron i guess mate. __________________ One thing you will learn with German cars - If it's simple it ain't happening. Last edited by DansSlk; 08-01-2008 at 07:01 PM. Reason: Forgot the private bus

08-02-2008	#4 (permalink)
Gabus Elite SLK World Member Join Date: May 2007 Location: Søgne Vehicle: 96 SLK 230K Other Toys: Volvo L3314N Posts: 437 Country: Thanks: 18 Thanked 66 Times in 47 Posts	Hei, og velkommen fra Søgne __________________ Gabus The Rolls Royce is the Mercedes amongst cars To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Has anyone installed a new radio head unit?	shanespin	SLK R170 General Discussion	12	09-07-2008 09:20 AM
Command Head unit not working	jmeredith	Ask DansSLK	20	04-11-2008 10:35 AM
Aftermarket Head Unit	Bubba	SLK R171 General Discussion	4	08-25-2007 02:11 PM
Head Unit	scrmnss	SLK R170 General Discussion	2	05-18-2007 12:46 AM
CYLINDER HEAD Piant Questions	SLKman	SLK R170 General Discussion	9	05-09-2007 06:49 AM

08-01-2008	#3 (permalink)
UK-C200 Elite SLK World Member Join Date: May 2008 Location: London, UK & Baton Rouge, Louisiana Vehicle: 04 RHD C200K Coupe, 06 LHD SLK-350 Other Toys: Nacra F18 Posts: 614 Country: Thanks: 41 Thanked 130 Times in 83 Posts	Welcome!! Dan has covered most of the basics.. I'd suggest you take a look at mp3car.com - it's a good resource for carputers. I've seen a couple that looked really good (2 din touch screen), and I think they were both running Linux.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Sponsored Links

Sponsored Links