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Your SRS light has come on and stays on, Also you noticed that the airbag off light stays on as well. Your car has never been in an accident, and your bags and belts have never deployed. You have some basic mechanical aptitude and don’t want to pay a dealer 500-800 $US for this repair. Read On…
It is not necessary but best to look for an independent mechanic shop that displays the 'pie', and have the codes read, this will tell you exactly what the problem is. Most will not charge for this service, and unless you have the MB software and can read the exact pin, you can’t do it..

Lets try and address the most common questions regarding this condition.

Q; - Is this a safety issue, the car still runs and a friend of mine who has a 2000 210 has a piece of electrical tape over the light and just drives it. Do the air bags still work?

A; No, Operation of all SRS devices are unpredictable, they may not fire at all, or they may fire for no reason

Q; How many Sensors are there and where are they?

A; Many.. The SRS system has a pre-tensioner in each seat belt, several air bags, sensors throughout the car to activate same, and a child sensor in the front passenger seat.

Q; Before I tear my car apart I would like to know as much as I can, what the module looks like and yhe functionality and design information

A; The child sensor adjusts air bag and seat belt level for the front passenger, and effects the functionality of several other devices.

Q; Is a sensor of some kind in the drivers seat?

A: No, a seat belt switch, and seat belt tensioner , and air bags.

Q; If I replace the Ass Mass will the light go off?

A; BE Clear Here, when you fix the fault, The Light WILL go off by itself if all faults have been corrected.

Q; How do I do this repair myself?

A; On the next posts, you will see a series of pics, but the procedure is,,,
1. At some point, have the codes read, by an inde, (PIC 1 ) as having the seat pad SRS light on will 'MASK' other ( emergency tensioning retractor belt and bag) faults.
2. Buy a NEW sensor first, (PIC 2 ) I have not seen ANY signs of wear ( wires, scraping, breaks ) at all. The sensor 'dots' fail with use/age. Sensors cost 140 US$ at MB.
3. TIP- Take the seat out of the car, period. If you have never done one, and are not an MB tech, or leather repair expert, 5 bolts and some clips and the seat is out. Don't even try to in car cover remove. you will me$$ it up!
4. TIP- Allow an extra 2 hours to shampoo the carpet under BOTH front seats. which is what you will do when you see all the gack under the seat. My car gets 'mini detailed' weekly and it still had lots of filth under the seat(s). Record amount of coins found so far.. $16.83 US$’
5. Unplug all wires from the connector block (PIC 6-7 )
6. Snap off the bolt covers (PIC 8 )
7. Remove all four 'Torx' type bolts (PIC 9-10 )that secure seat rails in place on the car floor.
8. Pull OUT not up on seat belt bolt cover(PIC 11 ) and remove bolt.
9. Release the wire cable (PIC 12 )
10. Tip the seat top down and remove the complete car seat from the car.
11. Remove the connector block and unplug the yellow sensor (PIC 13 ) connector from it's housing under the seat.
12.Take off the plastic side covers.
13. Loosen the 2 back bolts, (PIC 14-15 ) and remove the 2 front ones, This is optional and done to make the job easier.
14. Push down on the leather, (PIC 16-17 ) and pull out the bar that holds it to the frame.
15. Twist 90 degrees on the plastic ‘butterfly’ clips, (PIC 18-19-20 ) and release the leather cover.
16. Change out the sensor pad (PIC 21-22-23 ).
17. Once you have removed the sensor pad unit replacement is simply a reverse procedure. (PIC 24-25-26 )
 

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Next pics

Here are the next set of pictures.
 

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More pics

Here are the next set of pictures.
 

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The last set of pics

Final pics
 

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Looks pretty good. Do we already have something like this linked in the DIY stickies above?

Well, regardless, when you (or others) write stuff like this, please nominate your own thread in the DIY suggestion thread above. If you do find existing linked threads, please put links to them in in the post as well for comparison. There is no reason that we can't have multiple DIYs for the same problem, as long as things in the DIY stickies stay organized.

I haven't taken the time to add the stuff in the suggestion thread yet, but the thread isn't growing either (that's a hint).
 

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2 diys

nice to see a few different views.
The one thing you forgot is that a majority of the time the seat sensor is good,it is the wiring that gets frayed or pinched or broken.So always before seat removal check the wires are tested with a multi meter.
:bowdown:
 

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Hello all DIYers-
Now that I have the seat taken apart, I can't find the seat sensor pad anywhere but dealership. Where have you all found it previously and for how much? That $100 quoted above would be fantastic.

Thanks!
 

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Hi
Having the same problem with the light on my 99 300td wagon. It has cloth seats and I was able to get at it within 2 min with just by clipping the fabric on the bottom and sides and peeling up through the layers. The layout of the sensor seems different though, mine does'nt have wires going to the back of the seat, just one coming up from the floor, to a connecting block, then to the sensor. Thanks for all the tips guys

later edit
decided to risk it and follow olords tip about the wire being pinched, so I cut the wire from before the first cable tie to after the last cable tie (i.e. removed about 1 ft of cable) and put on connecting block. I figured what did I have to loose, I was going to have to get a new sensor pad anyway. This still gave enough space on the cable for the seat to go fully back. Bingo 3 days on and no sign of the SRS light!:bowdown:
 

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air bag sensors, on the fritz

Guys,
If I read this right, the problem is more likely the wires than the sensors, yes?
Well will the code readout tell us that?
Or do I ask the mechanic to change the gizmo and look at the wires? Since he will have to remove seat in order to see it all anyway and it seems like hundreds for the labor and a hundred for the device? Crackie!

much obliged, cover me I am going in guys,

Jeffinski
 

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Guys,
If I read this right, the problem is more likely the wires than the sensors, yes?
Well will the code readout tell us that?
Or do I ask the mechanic to change the gizmo and look at the wires? Since he will have to remove seat in order to see it all anyway and it seems like hundreds for the labor and a hundred for the device? Crackie!

much obliged, cover me I am going in guys,

Jeffinski
My indie has a code reader for that system and was able to tell me that all of the codes related to that failed sensor.
 

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The wires worked for me but my setup seems simpler with only one wire coming up from thee floor directly to the sensor. The light came on again yesterday (first time in over a month) while my wife kneeled on the seat to get something in the back, so maybe the sensor is on its way out too?
 

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Hi, I have the seat out of the car , the 2 front torx bolts and the 2 rear torx (larger 45) bolts removed but the dam seat adjuster mechanism doesnt want to part from the seat base.its like something else is stopping the 2 from parting. Any help welcome as I´m stuck at this part.

thks Tony
 

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Tony`
I think you are missing a bolt according to MRBSMITH there are 5 bolts. Take another look.
3. TIP- Take the seat out of the car, period. If you have never done one, and are not an MB tech, or leather repair expert, 5 bolts and some clips and the seat is out. Don't even try to in car cover remove. you will me$$ it up!

~donald
 

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Thanks Donald but the seat is out of the car , I refer to the bolts holding the seat adjustmnt mech to the seat base ,there are 4 bolts that hold this ,2 large at the back and 2 smaller at the front .
They have been removed and is still seems attached as it moves up a little at the front but them catches and I cant see what is the problem.

Tony
 

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Can someone tell me if the sensor changed as I bought a new one and it doesn´t come with the white plastic box attached , only a small circuit with resistors and 2 wires leading to a yellow connector , so thats a wire less and no box, its slightly different shape too .Part number 210 820 9710 -

thks
Tony
 
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