trendbuck

I have the dreaded SRS light on. I have had the fault diagnosed by mercedes dealer as the occupancy sensor in the passenger seat. Of course they want in excess of $1000 to repair. I searched the net and found an Occupancy sensor emulator. But unfortunately this did not work. Still in discussions with supplier but i dont hold much hope for it being resolved. What i did find however was that there is a fuse in the drivers foot well (fuse #1) which is labelled as "Airbag off indicator light" or similar. There is also an Air bag fuse in the engine compartment. I removed the F1 fuse and hey the srs light is no longer on. My question is does this fuse do what it says it does(ie turn off the light) or does it it turn off the airbags as well. I am thinking and wishing that it does just turn off the lights as there is another fuse in the engine compartment that says "airbags" specifically. I have searched the net for an answer but there are no schematics or detailed description about this F1 fuse.
Anyone got some ideas or knowledge on this?

benparson

Did you ever find out if the F1 fuse only turns off the light?

trendbuck

No i did not. I assume that it does. Thinking more about it. If someone wanted to put recaro seats in a benz then they would need to be able to turn off the lights. The manual i have is not very descriptive. But in relation to F1 it does say indication light not function. The other argument is that there are other fuses which control srs function and they are still in place. If you do find out for certain what this fuse does actually turn off i would be pleased to hear.

benparson

Thanks trendbuck. I'll ask my independant if he happens to know and tell you what he thinks.
Ben

Maj. Dundee

Yes, the F1 fuse only turns off the light on the dash. Whenever the Air Bag Off Light is illuminated, the passenger seat air bag will not deploy during an accident, whether or not the fuse is in place.

If the SRS light and the ABO Light are illuminated, no air bags will deploy in an accident.

trendbuck

Thank you for the confirmation. I only have the SRS light on and when I remove fuse F1 the light is now off. I deduce from the last post that this means that the Air bags will still deploy in the event of an accident. The only different being that the front passenger air bag will always deploy whether there is a passenger there or not. Is this correct?

Maj. Dundee

There's a little confusion here. When you reference fuse #1 I assume you mean fuse #1 in the right side interior fuse box, correct?

Also, what fuse # are you referencing in the main fuse box?

If so replace that fuse. Then turn the key to the ON pos. and check to see that both the SRS light and the ABO light illuminate.

trendbuck

Fuse #1 is on the right side interior fuse box. If i replace this fuse and turn on the ignition only the srs light it illuminated. The abo light is off.

The other fuses i was referring to are in the engine compartment on the right hand side when standing in front of the vehicle. I have not touched any of these fuses.

Maj. Dundee

Why haven't you responded to the last test in my previous post? Check to see if both lights illuminate when the key is turned on.

trendbuck

I have replied to your question. When i replace fuse #1 and turn on the iginition only the SRS light is illuminated the ABO is off.

Thanks
Mike

Maj. Dundee

Sorry, I missed that. I don't know if you just bought this truck, but it would seem that someone removed the bulb in the cluster to mask the ABOff light being constantly on or the bulb is burned out.

This should be addressed first before any repair is made so you will know if the repair was done properly and the system is working properly.

trendbuck

I think I need to be more specific about what happens when fuse #1 is in place. When i turn on the ignition the SRS light and the ABO light comes on along with all the others. After a few seconds the ABO light goes off but the SRS light remains on. (due to the passenger seat sensor being faulty).

Hope this explains it all,

Best Regards

Mike

Maj. Dundee

That explains everything. If there was a problem with the Child Seat Sensor, then the lighting of the two lights would be completely opposite. The SRS light would go off and the ABO light would remain on. M/B is fleecing you.

When you took it to them they must have charged you and in turn supplied you with a print-out and also stated the code number relative to the problem. Redact all personal info. and post a copy of that bill.

trendbuck

Attached is a copy of printouts and bill from MB. When the car first developed the SRS fault with SRS light coming on. IF someone sat in the passenger seat the srs light would turn off. But now it doesnt matter wether there is anyone in the seat or not.

Maj. Dundee

When I read your original post I took this statement as you tried to get an emulator from someone on-line but did not here from him. Is this correct or did you receive it and after installing it, it did not work?

If you did install the emulator, this is what is causing the confusion about what light goes off and which stays on. It's also safe to say that at the time M/B tested the system they were not aware that an emulator was in place.

trendbuck

The order of events with SRS light problem:
1. The SRS light only was coming on intermitantly.
2. i took the car to MB and they diagnosed the problem to be the seat occupancy sensor
3. I searched the net and found a supplier from china that sold a seat emulator for $36. (chinabuye). There was another in europe somewhere but they wanted around $80
4. I installed the emulator which did not work. In fact it made the problem worse. Both the SRS and ABO lights came on when it was installed. I then removed the emulator and reconnected the orignal wiring to the seat sensor. Only the SRS light on again now.
5. I then looked at the fuse box and found fuse #1. When it was removed the SRS light remained off.

I have not tried this but it may be that the emulator may work if the fault codes are reset. I am reluctant to test this as I dont have a diagnostic tool to do the reset and MB would probably charge me another $70 just to prove that the emulator is not doing the job.

Mike

Maj. Dundee

Don't you think it is odd that at the beginning both lights were on and after the emulator was installed and removed only one is on?

Now if you want it fixed the right way you will have to bend over at M/B. Hopefully you haven't damaged the SRS control module.

The only other alternative you have is to purchase the sensor which comes with the foam padding...........install it yourself or take the seat to an automotive upholstery shop and have them install it. Then you will have to find an independent repair shop that has a professional scanner and clear the codes.

trendbuck

I think you may have misinterpreted my last post.

Orignally both lights would be on when the ignition was first switched on and then only the AB light would go out.

After I installed the seat emulator both lights would be on when the ignition was first turned on and would stay on.

When i removed the the emulator the both lights would be on when the ignition was first switched on and then only the ABO light would go out. In other words back to the status before I installed the emulator.

I am now confused as to whether my original question has been answered. In your opinion does fuse #1 simply turn off the SRS and ABO warning lights? Or does it turn off the complete SRS and AB system?

Regards

Mike

Maj. Dundee

Fuse #1, when removed, turns off both lights and the entire SRS system. No air bags of any kind will deploy.

I don't understand the fascination with fuse #1. I hope you don't think that if you remove the fuse and the lights go out all your troubles will go away. You have a problem with the SRS system and it must be fixed. An emulator of any kind is not the way to go, as the safety of the passenger is at risk. How can you trust someone from China to protect you and your passengers.

trendbuck

If that is the case then. What is fuse number 16 under the bonnet for. It says airbag system. If what you say is correct and fuse number 1 turns of the air bag system, Why would have Mercedes have fuse 16 as well.

May I ask if you are a Mercedes Mechanic or a DIY'r like me.

john maddox

I have exactly the same problem. SRS light often remains on when passenger seat unoccupied - goes off when someone sits in passenger seat.

I am going to remove seat and check the pad for a break in the wiring or similar but while I am a confident at diy on my W163 I have no experience in removing seat upholstery and worry I can get it back ok.

In the uk a new seat pad sensor is £211 plus Vat which seems a lot of money for a simple part.

Can anyone reassure me that removing/replacing the seat upholstery is reasonably easy.

Thanks all

Maj. Dundee

Here are the instructions for removal of everything. If you are replacing the sensor, move the seat to the upper most position and then remove.

You will also need conventional male (T) Torx sockets and female (E) Torx sockets. It is not that difficult to remove the cover. Once the trim and backrest are removed, put the frame with cushion back into the truck with the two front bolts to hold things in place to remove the cover. Talcum powder on the inside of the cover and the outside of the foam cushion will aid replacement.

john maddox

Many thanks for your help and speed of response. Best Regards

john maddox

Well I decided to check all the wiring before removing seat and started by unclipping all connectors under the seat and spraying them with switch cleaner and reconnecting them. I have driven it 6 times and covered 80 miles since without any light. It would have come on at least 4/5 times before I did this. So fingers crossed I may have cleared some high resistance that was triggering the SRS light. I will post again in a weeks time.

Maj. Dundee

You probably did clear the problem. good luck.