Mercedes 2010 B-Class SRS Restraint system malfunction - Faulty Relay 

My problem.. SRS Restraint System Malfunction but nothing shows in the meter?? What exactly the mulfunction??

How did you find out that the relay B was defect?

Bonjour quel était le problème sur votre w245?svp merci d'avance

Initially I Googled for the fault and read various forums. I think first I did look at the pressure sensor, wiggled the wires, checked for lose cables etc. with no luck. When I replaced the relay (following reading a post from someone with the same issues and who fixed it with a new relay) I did not know if it would work. It was just a gamble. I also gambled on a diagnostic port to USB reader for the car, but I never used it once I realised that MB have their own hidden menus. So it wasn't all win-win. The stories of the pressure sensor being a protocol driven unit rather than an open/close switch scared me enough to not bother opening it up. Luckily I cleared the SRS fault message from the console, but I could well believe the need for trips to the dealer. Maybe the fault code is still in there! I don't have the B160 anymore, I upgraded to a newer GLA. The location of the relay (in the SAM hidden under the carpet and hard to reach) is a good example of the bad design I agree. But the new GLA has it under an 'easy to pull up' carpet. Better but not wonderful. As nice as the new car is, I miss the B160 a lot. Part-exchanging it was like loosing a family member. I kid you not. It was a sad moment. The GLA is great, but not as well sound proofed and viability from inside is limited by a massive central pillar and smaller windows. Trust your purchase, the B-class is a nice car!

Apart from the relay (and the odd scratch on the alloys) I've been really lucky. It's a nice car reliable car at a good price point. Thanks!

I spent a long time on Google and finally found a post on Mercedes-Benz Enthusiast Club Singapore's forums. I think the post is no longer there but it mentioned the wipers & SRS and the relay, and where to find it. I just created a video to spread the info. :) The fuse sheet and manual will tell you where the relays are. On a UK A160 I know the relays are in the same location, under the carpet in front of the passenger seat.

@@iloveimageprocessing Thanks, it is, I'll inspect that relay as soon as I can. If it works, I'll buy you a beer. :) Thank you for video, found it very helpful.

On the B160 it was the same relay that powered the SRS and wipers, part number "A 002 542 26 19".

I honestly don't know, but my personal view would be to go through the steps slowly and then use a multi-meter on the relay and see. I'm not a mechanic just a person with a dislike for spending lots at a garage! I couldn't say if a B150 had a different setup for the wiper circuit, but it is possible. Good luck!

Sometimes it is the seat cable tahtn connects the seat and the bode underneath the seat. From moving the seat it breaks the cable insulation which means resistance goes up and down willy nilly and the airbag SRS goes off 🎉🎉🎉🎉🎉

​@@iloveimageprocessingB150 is B160 with older software just less power same engine 1:1 the same 😅 Wiring should be equal at same trim level. Yours has some options I have seen but nothing mayor 😂

I have a A160 2011 and I am pretty sure the relay is in the same location, but I am not sure if it is the same relay. That said my B160 and A160 were similar in lots of ways. Also another commentor said that to clear the error after replacing the relay on the A-Class still required them to go to a Merc dealer. My advice would be to go carefully and locate the relay for the SRS circuit (read the manual / fuse sheet to locate the correct one). If you are handy with the multimeter you can check easily if it has failed. While you are there, check the relevant fuses etc. I'm not MB trained, just own a few Mercs. Only do what you are comfortable doing! Good luck.

Probably not related to fueling. I don't think it is the same issue as the relay, do the wipers work?

+iloveimageprocessing yes wipe works. I notice that the seatbelt light is gone whenever I unbuckle it.

Under the seat is a red connection box that connects the seat sensors. It might be that, and the SRS light is saying the passenger airbags are disabled because it thinks a child seat is present. Unfortunately I heard that the electronics in that is quite complex, more than just a few wires and that it sends coded signals. It could be just loose wires so check, but anything more I think you should get fixed properly - the passengers life might depend on it! Good luck!

jtcber . I have the same SRS fault as yourself. The guy here was very lucky imo, because his problem with the main display also showing SRS along with the red SRS light coukd equally have been the passenger seat pad, which is a pain to DIY. He was also very lucky in seemingly, he didnt need a diagnostic reader to reset his SRS display error, which is the norm for any display error code. Back to my problem, and one you have hopefully solved? Unlike this video, there is no SRS 'Go to Workshop' on the display, just the red SRS light.....and, like yourself, no seat belt warning chime when driving without belt on. This logically points to the seat belt anchor, but when I disconnected the red terminal block under the driver seat, and measured the resistance of the seat belt anchor two pin plug, it measured about right, ie. open circuit seatbelt unconnected, and just over 120 ohms or so seat belt connected. I am wondering if there is a fuse for the seat belt connection/warning chime but cannot find one in the main fuse block. Sods law says it will be one of the relays where this guy here accessed at not small hassle. So far, according to Google searches and Mercedes forums, I have found the design and general reliability of these B classes to be simply appalling. A Ford C max would have been better designed and more reliable, I suspect. But, I digress lol....did you manage to solve your problem with a replacement seat belt anchor latch?

A 002 542 26 19

Hello, sorry I know it is been a while but did you get it resolve and how? My 2009 GL450 showed the same and it won't start. my mechanic said it is a transfer case? I doubt it

@@FiestaAjayi yes I got it sorted i have a new car now fix the problem straight away 😂😂

I was not sure, but I felt like trying it. You could remove the relay and test with a multi-meter? Some people say that the SRS Fault (once fixed) requires a MB tech person to clear the fault. That was not the case on my B160 as once I cleared it from the steering wheel it was gone forever, but I don't doubt what people say. The question is do the other faults exist as well (light on the passenger sun visor and the wipers)? If they do, then it sounds like the same issue. If the wipers work then maybe it is just a fault code that needs clearing and if it keeps coming back when you do it, then go to MB I guess. Good luck!

@@iloveimageprocessing😊🤸‍♀️thank you very much for answering so quickly! My front whipes are working. I dont have the white lamps above the front window as you do. My new Mathies battry went flat. It took 5 times to go flat, when technical support ADAC believed that it was the new battery and not smth else. So since then SRS light is on the display. All the rest functions. When the defect battery was removed, the red swicht got disconnected. So ADAC technician explained the SRS light to be resulting from the disconnected red swicht under the driver's seat. When I came to the workshop, they connected the switch, but the SRS message kept lightning. The workshop read the mistake out and explained that "someone is sitting on the front passanger seat". They tried today the whole day, but couldnt get read of the SRS light. Then I found you video!😊🌹🤸‍♀️💃 Thats why Im asking- how did you realized, that it was this relay B? Or any other relay? And not say sensor on the front passenger seat?

@@iloveimageprocessing 😭😱Do you know how much does it cost to go to MB in Germany? To have a simple test, why the SRS message is lightning?😭😱

@@pininfarinarossa8112 I know, MB are expensive here as well, and some are not any good either. That's why I spent so long looking for the answer before going there. Unbelievable that the workshop could not solve it. That is terrible. I did read about the seat sensor, and I read it is complex and not a simple on/off sensor, but a communicating signal. I think I decided not to investigate more with the seat sensor because I decided I would not be able to fix something that complex. I found a comment online about the relay and so I took a gamble and went there to investigate. It was a guess/gamble really, not based on anything exact.

@@iloveimageprocessing 🙃🌹you gambled and you won!

I just fixed it. Thank you Lord and thank you to the guy the uploaded the video. Even taking it to a mechanic didn’t work, he did clean fuel inyectors and said did an oil change. Paid him quite a bit. When I picked up my car the SRS light was still on. I kept on searching and found your video, my car is C280, the relay was in the fuse compartment at the engine, once I changed: BINGO ! Thank you dear Lord and thank you guy for video. I video starting the car and cigarette lighter working, The SRS warning disappeared, I went to the mechanic to get my money back, he wasn’t there, I told his assistant that his boss mechanic didn’t fix my car and did mechanic work the car didn’t need. I sent the mechanic a text including video of the SRS on after I picked up the car from him. Also sent him a video after I fixed the car. And no SRS LIGHT ON He called me after 2 days and said I could come to the money back, I got about 70% back. I didn’t have to take it to have it to scan to erase. It just disappeared after I put the relay. I

Part number "A 002 542 26 19". Good luck!

Yes, I believe it was Relay B on my car, part number "A 002 542 26 19".