southsidej

Hi all,
Long time lurker, first time poster. I've got a 2010 C300 4Matic Sport (204.081) and I got the SRS Malfunction Left - Get Service message; no incident that coincided with it to my knowledge, just got in one morning and it came on. I've had the message for a little while, but it just became a priority issue as I failed my annual state safety inspection because of it. Now, I've done a number of things to resolve, to no avail, and I'm reaching out to the community to see if anyone has any advice. What I've done so far:

- I already had an appointment to get my Takada airbag recall done when it came on, so I just took it in hoping they would either fix it, or it was related to the airbag. No luck, they didn't fix it or even mention it when I picked it up.
- Scanned for codes with my iCarsoft MB II; the only code was 9B51 seat belt buckle Driver has a short circuit to positive. Ok, fine. I thought to try disconnecting the seatbelt while driving to confirm a faulty sensor, but I got the seat belt alarm when I did, which I thought was strange as it's a two wire sensor in the buckle, so it would seem to be sensing just fine. Cleared the code, but it came right back.
- Got a used buckle and replaced it. Cleared the code afterwards, but it came right back. Same behavior when I take off belt while driving.
- Checked my battery, it was a month away from its 6th birthday and resting voltage was at 12.25, so I replaced the battery. Cleared code and it came right back.

Now there are a few videos on YouTube of people demonstrating how to clear the 9B51 code after fixing a short under the seat, but they don't go into any detail on what/where the short was. I'm thinking that may be my problem. I'm going to have a look tomorrow to see if I can find any obvious connection issues on or near that yellow plug under the seat where the buckle connects to, but does anyone have any experience with shorts under the seat causing this, where they might be, etc? Thanks all!

southsidej

Update: In the event that someone finds this thread in the future, I resolved the issue by removing the pins from the yellow plugs on both the male and female sides, cleaning them up a bit, put the pins back in the plugs, then connected and disconnected the plug a number of times to try and scrape them clean for a good connection. That seemed to have done the trick as when I went to pull the code again, it no longer said the fault was "current and stored", just simply "stored". I was then able to clear the code and it never came back. Phew!

MBENZTECH

In the event that it comes back on...... Just replace the seat belt buckle. It is a common issue with W204 chassis.