SRS Connection under front seat

[rees_A]

Does anyone know which of the plugs controls SRS under passenger seat. I checked mine today and there was one the middle connection that has 2 brown wires going into it. It had one of the wires cut which may be why I have srs warning. I connected it back up but the light stayed on. Do I need to get the warning reset. I'm not sure I connected it properly as it needs soldering and I don't have a soldering iron so just sort of bodged it for now.

My question is, am I correct in assuming I have the right connector for airbag sensor

 

[cyberflex]

Hi, it is difficult for me to comment on SRS related stuff as it is best left to experts, as for the 2 brown wires, they are probably SRS bus wires and should be treated with due care and respect, you are not gonna blow a fuse if something goes wrong with the temporary fix you have made, but potentially something far worse,if I were you, disconnect the battery and solder and heat shrink the wire. I would not advise you drive around with the wire temporarily joined up, these are bus wires carrying digital pulses, if the temporary connection is not 100% secure and you drive over a bump, thus disturbing the temporary joint, a small change in electrical resistance could,(given a certain set of circumstances) cause a mal-trigger of all SRS related items in the car, which could be dangerous for you and fellow occupants, please, disconnect the battery, solder the broken wire, heat shrink it, take the car to somone with STAR diagnosis to run a test on the SRS system in your car and reset it, if no faults are found. There are specialists on this forum who do not rip people off, please search and maybe take a drive to visit one.
The SRS system in your car at the moment could well be in limp mode, meaning if there is an accident, a big one, heaven forbid, insurance investigators could well read the relevant module and void a claim, not really likely to happen, but stranger things in life have, so please make it a priority to re-solder, get the srs system checked and reset by someone with STAR and all will be fine.
Don't mean to scare, just that your car is powerful and it is best to get this sorted soon.
Cheers Jon

 

[Diesel Benz]

Which car is it (a CLK55AMG could be a 208 or a 209), which model year?

If you had two brown wires (no colour stripe), these must be ground wires probably intended to be connected to a common ground point.

 

[cyberflex]

Hi,
I think you could very well be spot on, on the w203 the power wires are at the front of the seat module in a 3 pin molex type connector. The communication wires are at the rear of the module as far as I am aware.
My thinking was, it seems strange for one connector to contain 2 ground connections, but, again, very possible depending on the architecture of the electronics inside the module,so as canbus wires are normally brown and brown with a red stripe, and the OP spoke of 2 brown wires in one connector, it seemed logical that these were bus wires, really is difficult to say without looking, but I know in most later Mercedes both canbus distribution blocks located under the carpet in the door sill areas are full of brown/brown-red bus wires.
My thinking was, what do those under seat modules control?
My thoughts were (depending on spec) power seats, seat occupancy, seat belt buckle sensors, side airbag control, seat heating, electronic lumbar support, seat massage, seat ventilation e.t.c.
Surely these must use some sort of bus system to communicate?
Anyway to the OP, the chances are it could well be a ground connection, but whatever it is join it well and get the car to a specialist/dealer to clear the SRS diagnostic trouble code.
Cheers Jon.

 

[x332race]

There are brown wires and connector to the front centre of the seat that go to the seat belt buckle and to detect when the seat belt is fitted.....I found this by accident when I was trying to work out what was wrong with the seat belt presenter in my CLK.....I pulled the connector out and the SRS warning came on on the dash display.....reconnected it and the warning luckily went away.....you should be able to trace the wiring from the seat buckle to the relevant connector.

 

[rees_A]

Thanks for all the responses. There are 2 brown wires, 1 with red stripe, soldered to 2 round pins that plug into the middle of the front of the passenger seat. I have not driven the car since putting the wire back on. Should I Disconnect and get soldered properly before driving or leave my temporary connection in place. Thanks again in advance for any replies. My Car is a 2000 W208 for info..

 

[cyberflex]

I believe they are bus wires, brown/brown with red stripe, if you are sure about the quality of contact being made,leave, but personally I would disconnect battery(WITH KEY OUT OF IGNITION, infact leave key out during all of this),disconnect temporary fix, strip wire with sufficient amount of copper, being careful not to lose any copper strands and solder up, heat shrink and go to someone with star to run a short test and reset.
I like stuff like this perfect, so I go all out to achieve perfection/safety, where wiring is concerned, but I am no expert and I am not pretending to be, so by all means take what I say, but make your own mind up as to how perfect a fix you want to carry out, I have seen some shocking joints that have lasted years without a hint of a short/arc.
Cheers
Jon.

 

[bouncer]

SRS errors need to cleared using STAR.


sTeVe

 

[Baron_Samedi]

Not always....

 

[rees_A]

OK update, I've checked the wire again for colour etc. Its the middle 2 bullit type ocnnector under the passenger seat. I've had the faulty wire soldered and plugged back in. Just have a quick question -

I put the 2 connectors back in the connection box and am not sure I got them round the right way. I have a brown/white wire that is on the top (Closest to bottom of seat)and under that a solid brown one(Closest to floor). The plug is back in the car now(It has space for 4 connections but only 2 are wired.

Can someone please check their W208 and make sure I got them round the right way.

Thanks again for all help

PS. The SRS light is still on so I guess I need to get the fault cleared..

 

[rees_A]

OK, so just had a look at fuses under bonnet to make sure all is good and have found fuse 2 missing which is supposed to be for airbag/sidebag control unit? This could be why my airbag light is still on. Can someone reply to previous post and confirm they have a fuse 2. I'll then plug the cables in correctly and add the fuse. Hopefully I will then have fully functioning airbags.....Perhaps someone removed the fuse when the srs light came on rather than fix the problem..Not really sure but a little perplexing to say the least!!!

 

[Diesel Benz]

OK update, I've checked the wire again for colour etc. Its the middle 2 bullit type ocnnector under the passenger seat. I've had the faulty wire soldered and plugged back in. Just have a quick question -

I put the 2 connectors back in the connection box and am not sure I got them round the right way. I have a brown/white wire that is on the top (Closest to bottom of seat)and under that a solid brown one(Closest to floor). The plug is back in the car now(It has space for 4 connections but only 2 are wired.

Can someone please check their W208 and make sure I got them round the right way.

Thanks again for all help

PS. The SRS light is still on so I guess I need to get the fault cleared..

Shouldn't you use the wiring diagram for reference when you work with your car? If you do not have it, someone from the forum would email it for you (a copy for personal use).

Fuse #2 appears to be supplying power to the child seat/passenger seat occupancy sensor. But this sensor should have a connector with three wires, pin #1 pink/black from fuse #2, pin #4 brown ground wire and pin #3 should have a brown/white wire that goes to the SRS control unit. Are you not working with these wires and the related connector?

 

[cyberflex]

Hi, I just thought it was a case of the wire being broken by accident, I understand now that maybe this is an issue from a previous owner, if it is and you have just bought the car, it is anybodies guess as to what has gone on before.
I agree with diesel benz, you should be working with some type of schematic diagram, if the fuse is meant to be there and was removed, maybe the same person snipped the wire/s for a reason, the non-trusting part of me would say for the sole purpose of getting the car sold, without having to replace a costly module/sensor.
I guess the others with diagrams will help you, you could probably get the fault cleared with snap on, win-star, bosch e.t.c. loads of places have invested in these, but now I know a bit more about the situation I advise you to get it to a dealer or a specialist with STAR to run very specific tests if the srs DTC does not clear or reappears after being cleared.
Wish you the best

 

[rees_A]

The plug I'm looking at is in the middle of the seat at the front. It only has 2 pins and plugs into the seat which has 2 pins so I don't think its the one you are thinking of. The fuse issue may be why the srs light is on . Can anyone take a pic of their W208 Passenger seat wires that way I can match that against mine.

 

[cyberflex]

Rees, i would do it for you, but I have a W203, hopefully someone will do it for you, if not go down to a dealer and ask them if you can take a picture, if you explain it, I do not see why it would be an issue. Failing that you could hunt about independants, there are a fair few W208's around car sales places now, but the chances of their cars having the spec and thus the same wiring setup as an AMG car are low. Worth a try though.

 

[Diesel Benz]

The plug I'm looking at is in the middle of the seat at the front. It only has 2 pins and plugs into the seat which has 2 pins so I don't think its the one you are thinking of. The fuse issue may be why the srs light is on . Can anyone take a pic of their W208 Passenger seat wires that way I can match that against mine.

While waiting for a W208 car owner, can you find the part number from the plug? The problem I have is that from the wiring diagram of a MY2000 W208 I cannot find any part with a pair of brown & brown/white wires. Could it be that someone has worked with the SRS system and it now has only the weight sensor with two wires? Older models have such a sensor (you could report the build date but you car cannot be old enough for the other option, the wire colours would be different for the two wire sensor).

 

[rees_A]

I don't think the plug had a part no....I'll have another look to be sure. I've seen a couple of posts where the 2 wire plug below the passenger seat has been mentioned so I'm assuming it is ok. There is no sign of any wires missing or being cut so I think it's ok. I would just like someone to post a pic if they could, I can then check mine is connected properly and then put a fuse in. Hopefully this will fix the problem. There is a clk430 for sale in a local garage for I may just go there to take a look quickly if no-one can help.

 

[rees_A]

Any W208 clk owners wanna post a pic of the connections under their passenger seat....I would be very thankful as I don't want to blow anything up putting a fuse in...LOL

 

[cyberflex]

Hi Rees,
Just thinking, I had a look at my w203 seat controller and brown seems to be at the bottom (closest to floor) in the 2 way multiplug. My other colour is different to yours though, but maybe Merc rule of thumb is brown is always at the bottom in this scenario, cannot be sure though mate.
I reckon you could start a fresh thread with a direct title appealing to w208 members in this and maybe some other sectors of the forum aswell as other forums. It may not get seen here.
See Ya.

 

[rees_A]

I'm sure that sounds right. I think my solid brown wire is closest to the floor. I'll go with that and see what happens...