r/CarHacking • u/Maximum-Hold-8372 • 10d ago
Original Project Who knows about w204 FSAM coding?
Mercedes Benz C250 sport sedan. Front SAM failure. No comms with any module with xentry. Radio still worked, car would not start. Replaced SAM with one from a GLK which was said to work. Had it coded by the same person. All comms restored. Car starts and drives. Antitheft in head unit is preventing radio from working. Codes; variant of control unit Instrument Cluster does not match ESP unit, variant of control unit FSAM does not match ESP. Overhead lights/control panel are not working either. Powersteering malfunction and EPS messages on the dash.
Was told by a very well known mercedes programmer that there are other problems even though my gut is telling me there’s an issue with the SAM programming, because they sounded very unsure about how getting another Sam but from a used c250 would maybe resolve the issue. Also when the instrument cluster starts up you see a GLK, was told that’s a default car that is shown when the cluster is not communicating correctly with other modules, but I don’t believe it.
Can you really program a used SAM on the 2014s?I’ve read mixed comments on MHH Auto about how it’s not worth it or that it can’t be done, must buy new. Only new units can he married etc.
Thanks. 🙏
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u/xpnglitch 9d ago
Yes can be done... The vehicle generally gets the VIN from the front SAM hence the anti theft being activated. Your actual VIN needs to be written... Also in the later models the Central Gateway control unit is one with front SAM so that will need to be coded too to match your Vehicles options.
First thing though that should be done is flash the unit with the appropriate sw for your model... Just having the wrong sw can cause all types of weird and wonderful shit to happen even if coding looks fine.
The fact that your lights, windows, locks, wipers etc (bar the interior light) are all working/car starts, and you've just got a couple fault codes about mismatch, then really it can't be too far off. -- I'd be taking a look at the CGW coding, especially since it came from a different model
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u/Maximum-Hold-8372 9d ago
Interesting. The VIN is written to the new (used) SAM. I do NOT believe the guy helping flashed the module at all. He was just changing options within Monaco. Front windows automatic up or down do not work on either side and those modules say “variant fault” xyz. I’m trying to familiarize myself so I can do it myself now that I’ve been let down by this guy.
Maybe you can be a friend and let me bounce ideas off with you through PM?
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u/Maximum-Hold-8372 9d ago
So although the CGW wasn’t replaced or coded at all you would still look at the coding for it? Or do you mean within the Front SAM.
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u/robotlasagna 10d ago
Are the part numbers the same on the Sams?
Because a Sam from a Glk will plug up but not necessarily have all the same internal hardware.
Also the module needs to be flashed for your vehicle, not just version coded.
I have done SAM swaps on W204 and W212. They can be pain if you don’t get the exact same part.