Hi everybody! This is my first post but I have been browsing these forums since I bought a 2008 CLS 550, I picked it up after it was in a front-end collision and rebuilt it. Sorry if the story is hard to follow and the formatting is weird, I just have a few questions that I was hoping somebody here could help me answer.

I replaced all the blown airbags, had the seat belts repaired, and sent the SRS module off to be reset. I was informed that the module could not be safely reset so I ordered a similar unit off eBay, though I fear it may not have been similar enough. (I should've done more research first). It came out of an E 63 without a kneebag. Using my Autel MP808 I unlocked it, changed the vin, set country to USA, set kneebag to present, WSS to not present, auto child seat recognition to not present, and seat mat to no mat (I need to diagnose/replace the WSS/child seat recognition later but want the airbags to work for the time being).

So all that leads to the problem I encountered, after all that is set up I get one error in the SRS module, AD52 control module N2/7 (restraint systems control module) is faulty. I thought I had to lock it first so I cleared the error, locked it, but the error came back after interlock. I subsequently ordered an SRS module from my same exact car, same plant, same everything, just different production numbers. The seller assured me that all the bags and seatbelts were intact from the car. This module was $40 shipped, whereas the cheapest new module I can find from a dealer is just shy of $600. The SRS module I ordered from the same car as mine will arrive in one week.

* My main question: Is this error because the module is faulty, or because it won't work if I change things like the kneebag/WSS? (I tried initial setup to interlock, and special functions then lock. It would not work either way but I need to use special functions to disable the seat mat).
* Question 2: Can I make this work by reprogramming a used module or do I have to buy a new one then set it up?
* Question 3: Does my car have the seat mat or is it just the WSS module/4 sensors on the passenger seat rails?
Additionally, the error for the auto child seat recognition (when I set it to present) is component B48 has open circuit which I am thinking it might just need to be replaced, hence the third question. (The wiring under the seat checks out)

Thank you for reading, hopefully some of you have experience with the SRS in these cars and can help steer me in the right direction.

 

Hey guys thanks for all the help! Just kidding, I know it's a complicated subject but I do have an update for anybody that might be interested in what I found out.

The matching airbag module seems to have worked and my WSS (which is not the seat pad, it's a different system that serves the same purpose) for some reason stopped throwing codes, so I guess it works now. The last thing I have left which I never noticed before is that the driver seat buckle pretensioner has deployed, so it scrunched up the seat buckle and that is the only code I have (too high resistance, because it's deployed).
I ordered a replacement, so once that pretensioner gets here I should be able to lock up the SRS module and I'll have a functional supplemental restraint system.

I have no idea what I'm talking about here but I think it's plausible that if you stray too far from the stock programming on these modules it will throw a faulty module code. This has been a learning experience for me so hopefully someone else will see this and it might help them out too.

 

I'm awaiting replacement seatbelts to get to me. I ordered them off Ebay, I hope I don't encounter those problems! I have to replace both rear belts and the driver's seatbelt.

 

You will have to erase the crash data from the SRS module if the pretensioners have deployed. I never updated here again but I was able to get everything working properly with the replacement module and everything else, no more SRS light.

 

Is there a way to manually check if the pretensioners deployed? I had no idea those would also have to be replaced.

 

If you had to replace the seatbelts then you're most likely going to have to reset crash data in the SRS module. I'm not sure if it's the same way on all the cars but mine has a pretensioner on the buckle that bolts to the front two seats, so your car might have that too and it might need to be replaced. You're replacing them because the vehicle was in a collision, right?

 

Yes, I purchased it after it had been involved in a collision and have been repairing little by little. Good thing you told me, I'm going to likely remove them now since I have a lot of the interior taken apart.