SRS light always on - PeachParts Mercedes-Benz Forum

sokoloff · #1 10-28-2007, 10:31 PM

Can someone tell me which part in the steering wheel typically causes the SRS light to stay on? In looking at the parts catalog, I see part # 124 464 02 28 called a contact assembly for the SRS system. There is one of them in the steering wheel and the cost is about $100. The other possible part is part number 124 460 05 41. It is called a horn switch and there are two of them. Cost is about $15 each. The thing that confuses me is that the second part looks like it is the contact ring that others say needs to be replaced to correct the SRS light problem. I'm ordering some parts and would like to order the right part(s) the first time.

This is on my 560SL BTW.

Thanks.

Roncallo · #2 10-28-2007, 11:24 PM

Quote:

Originally Posted by sokoloff

Can someone tell me which part in the steering wheel typically causes the SRS light to stay on? In looking at the parts catalog, I see part # 124 464 02 28 called a contact assembly for the SRS system. There is one of them in the steering wheel and the cost is about $100. The other possible part is part number 124 460 05 41. It is called a horn switch and there are two of them. Cost is about $15 each. The thing that confuses me is that the second part looks like it is the contact ring that others say needs to be replaced to correct the SRS light problem. I'm ordering some parts and would like to order the right part(s) the first time.

This is on my 560SL BTW.

Thanks.

What makes you feel the problem is in the stearing wheel.

The horn switches are not a problem.

There are 3 pices in the stearing wheel that can cause an SRS problem

A124 464 02 28 ring
A126 464 09 43 brushes
and the bag itself.

John Roncallo

unkl300d · #3 10-29-2007, 12:13 AM

Try moving the steering wheel back and forth as if to clean away crap. Then try to reset it by disconnecting the battery for 30 minutes or more.
If it goes back on, then you can try replacing parts.
Also once you disassemble, you might just be able to directly clean the ring,brushes etc.

Do an archive search.
My w126 had intermittant srs light. Cleaning helped. no problem now.

BUT my C280 has it now. Goes off after 3 minutes.
Can't reset via battery trick.

sokoloff · #4 10-29-2007, 10:26 AM

Thanks to both of you. I think one of your posts I read in the archives. I think I may just try to remove the steering wheel and clean it up in there and see if it fixes mine too. I really hate to throw parts at a problem.

Thanks for the part numbers John. Time will tell I guess if I need them. I saw another thread where someone had a connection under the seat seat disconnected and that fixed his SRS light issue.

What kind of a test light do I use to check the nine pin connector under the hood? MB Doc in one of his posts talks about getting a reading from it to determine the issue.

Thanks.

unkl300d · #5 10-30-2007, 09:23 PM

I just had the SRS code erased from my 1995 C280's computer by a friendly benz mech. . Evidently while replacing the instrument cluster light bulbs, having left the ignition key on in order to rotate the steering wheel and negotiate the cluster out and also having removed one bulb for a sample, caused the SRS system to notice a fluctuation of current and thereby making the light appear (although it went off after 3 minutes.).
Now it goes off instantly.

So, for owners of 1995 C280, disconnect the battery when removing the cluster and don't remove a light bulb if you put the cluster back in temporarily.

Author of this thread, maybe there is another source instigating your SRS light ???

sokoloff · #6 12-09-2007, 03:15 PM

Got around to removing the steering wheel on my 560SL to clean out and take a look at my airbag contacts. Have a couple of questions.

Is it possible to determine the age of the airbag? If the airbag was replaced on the car for some reason, is there a date associated with the airbag serial number that Mercedes or someone else can look up?

The inside contact area was not terribly dirty, but I did clean it up and blow out the carbon residue. Before I put it back together and hope that just cleaning it up fixed it like some others have reported, is it normal for the two outer rings to be grooved? The two outer rings have a pretty good groove worn into them by the four outer brushes. The two inner rings are not grooved at all. The brushes themselves seem to have some life left in them. Since this is the first time I've seen the airbag contacts and rings, I need to know what is normal and what if anything needs to be replaced.

See attached photos.

DanielG · #7 12-10-2007, 10:01 AM

search this -- but I believe that the driver seat belt is also part of the system that can cause the SRS indicator to light.

sokoloff · #8 12-10-2007, 06:16 PM

Thanks Dan. I put it all back together and the result is the same. SRS light is on continuously about ten seconds after I start the car. To my untrained eye, the brushes and the contact rings are okay, so the problem lies elsewhere I assume.

glenmore · #9 12-10-2007, 08:31 PM

I had an intermittent SRS light that progressed to it on all the time. The archives suggested seat belt buckles, loose ignition tumbler, and most often, the ring or hub. Sometimes the SRS light would flicker with movement of the steering wheel. I threw some cheaper parts at it like the brushes trying to avoid the cost of the hub. Visually my hub seemed to be fine also but after taking it all apart several times, I finally replaced the hub which solved the problem.

glenmore
1991 300CE
2000 C280
1990 LS400

Lord Hemming · #10 12-12-2007, 12:25 AM

I have had this problem on more modern cars, both times it was caused by the 'switch' under the drivers seat. I am a 560SL owner, but I'm not sure if the car is sophisticated enough to have a seat switch.

I don't have a repair CD (hurry up Performance Products!), so take a look at a CD or speak to someone before your rip your drivers seat to pieces

sokoloff · #11 01-06-2008, 08:29 AM

Built a code reader and it looks like I've got a bad airbag control module.

sokoloff · #12 02-02-2008, 01:18 PM

Sorry for posting this in two different threads on the SL forum, but I thought that maybe someone looking at only the title to the thread might not open the other one.

Len

After building a code reader and testing the SRS system, I get a #2 error code that according to the codes tells me that the control unit is bad. I want to verify with someone in the know before I commit to buying a new/used part. It is my belief that the control unit the error code is referring to is the sensor located behind the climate control unit in the dash. My original unit shows part #003 820 73 10. That part has been replaced by part #004 820 17 20 and then by part #000 820 68 26 according to the EPC. The EPC also shows a condenser (energy reserve) and a voltage transformer electrical unit that look like they are located somewhere behind the driver's door. I guess one could possibly call these control units too. There is an error code for voltage supply which I would guess may refer to a bad voltage transformer. I see no error code that would lead me to the condenser.

Can someone please verify for me that error code #2, control unit, refers to the part behind the climate control unit like I think it does? I don't want to throw money away at a part I don't really need.