Bob66

I want to connect a CAN BUS car alarm to my W205. Apparently it is compatible with W222/W205/W217, but no vehicle CAN wiring information is given in the documentation. I found a wiring diagram online showing CAN access behind the COMAND APS NTG5 head unit, showing:

CAN-H = Yellow/White (pin 37)
CAN-L = Yellow (pin 31)

But I don't want to pull the head unit due to the trouble involved, hence this post.

In other MB models, B CAN wires could be found under the plastic side panel or carpet, usually these colors:

CAN-H = Brown/Red
CAN-L = Brown

But what are the CAN B colors for the W205 in that same location? Or is there another relatively easy to access location (i.e., NOT behind the head unit)?

Thank you.

Plutoe

Don't worry about the colors------look to the pair of wires that are twisted--the twisted pair is the CAN

Bob66

Actually, there is cause for worry. There are numerous twisted-pair wires throughout the car. This is true of any car, not just MB. Some twisted pairs can be used when adding Car Alarms, Speed Lock devices, digital information displays, etc., but most twisted pair wires cannot. That's precisely why the OBD coupler cannot be used either. It can on some Toyota cars and other Japanese makes, but not on most European cars, including MB.

Once again, I am in need of accessing CAN-B, not engine CAN or any other CAN. I need to know an easier-to-access location than behind the radio (head unit). If someone can please provide me with LOCATION and WIRE COLORS, from experience or from a schematic, I would truly be grateful.

If none of you know but someone has a schematic of CAN B wiring, I would appreciate having a look at that.

Thanks.

MBtech764

so you're just looking for a place to tap into the interior can? you my friend need to dig for the can bridge. Its a rectangular shaped block with about 10-12 2 wire connectors plugged into it. You're looking for brown and brown/red tracer, and yes they are twisted. There's a can bridge on either side, just inside front door sill. You'll need to pull up the sill trim cover, the kick panel cover, possibly the seat, and lift back the carpet. There's a black plastic cover under the carpet, pull that cover off and youll see a mess of wires, pull up the can bridge and plug your alarm can wires into an open slot and test it out.

vic viper

Interior CAN is Brown and Brown/red , just tap into any twisted wire or a distributor as mentioned above.

MBtech764

Yeah Vic seems right lol

In my .02, I'd rather plug into the bridge instead of splicing can wires. It'll make it easier to disconnect when something goes wrong. Sure its just 2 wires, but I've seen many techs get their asses kicked by 2 wires. If you can handle it go for it. Good luck sir

Bob66

Body CAN, yes. Thank you for the guidance. I will give that a try within the next day or so and then post back here with the results.

Bob66

Today I confirmed that the B-CAN wires are indeed as follows:

CAN-H = Brown/Red
CAN-L = Brown

Found under the carpet, as discussed here. However, the W205 has changed from earlier MB models. B-CAN in the W205 is 250kbps, which is new. CAN signals are different too.

Thanks to everyone who contributed to this discussion.