Help with 2007 C280
Thread Starter
Newbie
Joined: Jan 2018
Posts: 6
Likes: 2
2007 C280 4MATIC
Help with 2007 C280 SRS Issue
Hello everyone,
I recently purchased a 2007 C280 4matic with 90k miles. Overall the car is very clean so I decided to buy it based on that. The ride home was smooth however I do have a couple issues I am asking for help on.
The first is the SRS light is on. I bought an iCarsoft MB II diagnostic tool because I am a DIY'er. The SRS code is: "9203 The resistance value in the ignition circuit containing component R12/7 (right rear ETR ignition squib) is too high." I assume this has to do with some sort of SRS system in the back of the car. Is assume "right rear" is the rear passenger side? Does anyone what what component R12/7 is? I am still waiting on a service manual and I did find some information via Google but not enough. I am really looking for a place to start on this issue.
The second issue is pretty minor. The OBD II plug is loose. There is a black plastic assembly that has a door that allows access to the plug, and has 2 screws that hold it in. The plug itself is loose however. Does that plug seat into the black plastic assembly with the lid that covers the connector? I am not 100% sure but it seems like it would. Not a huge issue by any means, but would certainly like to fix it.
Thanks in advance.
I recently purchased a 2007 C280 4matic with 90k miles. Overall the car is very clean so I decided to buy it based on that. The ride home was smooth however I do have a couple issues I am asking for help on.
The first is the SRS light is on. I bought an iCarsoft MB II diagnostic tool because I am a DIY'er. The SRS code is: "9203 The resistance value in the ignition circuit containing component R12/7 (right rear ETR ignition squib) is too high." I assume this has to do with some sort of SRS system in the back of the car. Is assume "right rear" is the rear passenger side? Does anyone what what component R12/7 is? I am still waiting on a service manual and I did find some information via Google but not enough. I am really looking for a place to start on this issue.
The second issue is pretty minor. The OBD II plug is loose. There is a black plastic assembly that has a door that allows access to the plug, and has 2 screws that hold it in. The plug itself is loose however. Does that plug seat into the black plastic assembly with the lid that covers the connector? I am not 100% sure but it seems like it would. Not a huge issue by any means, but would certainly like to fix it.
Thanks in advance.
Last edited by Skrimps; Jan 24, 2018 at 11:22 AM.
MBWorld Fanatic!
Joined: May 2017
Posts: 2,290
Likes: 434
C320
R12/7 is the right rear pyrotechnic seat belt pretensioner. When the airbags go off it tightens up the seatbelts to keep the passengers in place. I would clear the SRS code and see if it comes back. If it comes back it could be as simple as a loose plug. If the pretensioners is bad you can probably find a used one on eBay for cheap. Just search for the part number. There isn't a single w203 PN I haven't been able to find cheap on eBay.
Don't you love icarsoft? It makes these cars so easy to diagnose and repair.
Don't you love icarsoft? It makes these cars so easy to diagnose and repair.
Last edited by tjts1; Jan 24, 2018 at 01:32 PM.
Thread Starter
Newbie
Joined: Jan 2018
Posts: 6
Likes: 2
2007 C280 4MATIC
Hello,
Thank you for the response. I assume the pretensioner is part of the assembly under the rear seat that the seat belt buckle plugs into? It wouldn't be anything behind the C pillar, correct? I suspect someone has already been in there but I will have to inspect the pretensioner and the wiring. I did try to clear the code with the tool, but it came right back.
Thank you for the response. I assume the pretensioner is part of the assembly under the rear seat that the seat belt buckle plugs into? It wouldn't be anything behind the C pillar, correct? I suspect someone has already been in there but I will have to inspect the pretensioner and the wiring. I did try to clear the code with the tool, but it came right back.
Thread Starter
Newbie
Joined: Jan 2018
Posts: 6
Likes: 2
2007 C280 4MATIC
I was able to look into this problem today. I tested the seatbelt pretensioner with a DMM and confirmed that it was indeed good. I suspected it was a wiring issue at this point. I found that the airbag module was nicely placed way up in and under the climate control panel. So I had to remove the center console (not too bad to do) and the climate control module. It was a tight fit but was able to remove the airbag module and found the 2 wires coming from the connector (red/yellow and black). Red/yellow had continuity, the black wire did not. There is a break somewhere between the connector and the airbag module. I was able to confirm this by bypassing the suspected bad wire with alligator clips. The code cleared and did not come back. Will be running a new wire tomorrow. Hopefully this will help someone who has a similar SRS issue with a confirmed good pretensioner.
Newbie
Joined: Oct 2014
Posts: 11
Likes: 0
From: Cleveland, OH
1998 SL500, 2007 C280 4m
How did you test the pretensioner? Never mind - I see now you test for continuity on the connector with a DMM
Last edited by slsmag; Mar 1, 2018 at 12:29 AM. Reason: figured it out
Thread Starter
Newbie
Joined: Jan 2018
Posts: 6
Likes: 2
2007 C280 4MATIC
Remove the pretensioner/buckle assembly from the car. Look down inside the connector and you will see a shorting bar that is touching the two pins. You need to wedge something small in between the shorting bar and the two pins. Once done, measure the resistance of both pins by probing them. IIRC, you should see between 2.0 and 3.0 ohms. In my case I saw 2.8 ohms and was able to determine that the pretensioner was good. A reading other than 2-3 ohms could indicate a bad pretensioner. Om my car it was a broken wire that was causing my problem. I ran a new wire and the problem went away.
Last edited by Skrimps; Mar 1, 2018 at 12:50 AM.
Newbie
Joined: Oct 2014
Posts: 11
Likes: 0
From: Cleveland, OH
1998 SL500, 2007 C280 4m
Remove the pretensioner/buckle assembly from the car. Look down inside the connector and you will see a shorting bar that is touching the two pins. You need to wedge something small in between the shorting bar and the two pins. Once done, measure the resistance of both pins by probing them. IIRC, you should see between 2.0 and 3.0 ohms. In my case I saw 2.8 ohms and was able to determine that the pretensioner was good. A reading other than 2-3 ohms could indicate a bad pretensioner. In my car the pretensioner was indeed good and it was a broken wire that was causing my problem. I ran a new wire and the problem went away.
Odd that on my car the SRS light came on when a shop replaced the brakes and rotors.
I'm still trying figure out if it was coincidence or if they broke a wire.
Trending Topics
Thread Starter
Newbie
Joined: Jan 2018
Posts: 6
Likes: 2
2007 C280 4MATIC
You would need to have the SRS code before you could start troubleshooting. In my case I have an iCarsoft MB II so I was able to read the code and find out exactly where the issue was. In your case it could be something very simple and easier to fix than my issue. I do not think a brake job would cause any trouble with the SRS, but anything is possible. Feel free to reach out to me if you need any other help or if you determine what code is stored.
MB World Stories
The Best of Mercedes & AMG
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
