Help. srs lamp flashing after recall

[wags]

Hi, wonder if a knowledgable person on here can help me with a problem on 2007 c220 sport w204...

Got a letter from Mercedes saying my car has a recall to replace SRS control unit

Took it in today and when I picked it up the service guy said there's a fault on passenger seat pad and module needs replacing cost is £364.60 . When I started car the airbag warning light is flashing.. It's never done this before in 5 yrs of ownership. Told service guy and he said that because of faulty seat pad.

Over the last year there has been a very intermittent message on the dash saying Front left malfunction contact workshop. But never has the airbag light come on.

is this correct, I feel they havnt done something properly and blaming it on the seat pad. There's no messages on the dash at present only the flashing red srs light...

Thanks , Alex

 

[richard]

I would not drive this.

I suspect the initial startup has not completed on the SRS module (because of the passenger seat sensor happened to be in it's intermittent state at that time) and thus your airbags may not be working. I seem to recall that the flashing SRS light means the new SRS controller hasn't been locked to the car yet.

If its not finished it's startup properly, you can be pretty sure the airbag system is not working as it should. And of course there is a risk it is not working at all.

I am surprised the dealer let you leave.

Richard

 

[wags]

All the dealer was interested is in selling me a new pad sensor for £364.60

How can I get them to put the new module in correctly. This morning I noticed the srs lamp flashing when I put key in slot before starting car,, never done this before.

Thanks for helping,,,

 

[Trickythemerc]

The fault is with the seat pad sensor, not the SRS module. The built in safety features of these things are designed to fail safe and not allow the system to run if there are any faulty components. As Richard states you will have no airbag or anti submarine check on the seat belts. Needs to be sorted ASAP as you may have insurance issues in the event of a claim.

 

[Codger49]

Think you will have to do something pdq here.

As Richard's post #2 above states the new SRS module must be coded to the car for it to be driven safely.

However, the currently installed seat occupancy sensor seems to be preventing this. Therefore you must fix the seat occupancy issue and then get the new SRS module coded.

£364.60 may be just the price for a new occupancy pad, fitting usually requires the seat to be removed and dismantled which won't be cheap.

Ebay has a W204 seatpad at the moment for £90 which may help 2011 Mercedes Benz C Class W204 Passenger Airbag /SRS Seat Mat Occupancy Sensor | eBay

Or there are modules (at £40-50) around that bypass the occupancy sensor and present a permanent 'seat occupied' signal to the SRS module. e.g. Mercedes Benz C W204 GL X164 ML W164 R X164 Seat Occupancy Matt Airbag Module | eBay

Issue with these is whether your MB dealer would recode the SRS module with this non-MB gubbins fitted (maybe an indy would?) and that you can not use a child seat in the seat with one of these fitted as the airbag will always activate.

 

[Codger49]

Sorry, forgot this point: sometimes fault indications from the seat occupancy pad have arisen from chafing of the wires leading from its location within the seat base to the connector block at the front of the seat. Could be worthwhile to check this out first.

 

[wags]

Good news, armed with the info gained on here Mercedes have agreed to change seat pad sensor free of charge so they can program the module.

You were right that the alarm from the seat pad stopped them programming the new srs module.

Thanks for the info

 

[richard]

Now that is what you can call a right result

R

 

[Codger49]

That is a very good result.

I wonder what it was that triggered their favourable reaction.

Perhaps their technician should have thoroughly checked for current and/or stored faults before proceeding to replace and code the SRS module.

 

[wags]

Your correct,, they said they didn't realise that an outstanding fault will cause a problem programming new module. Mine was the first they had a problem with. They said from now on they will not change module with current faults in system.
It's a learning curve for them and me ,,,

 

[richard]

I wonder what it was that triggered their favourable reaction.

I suspect someone twigged that they let you drive away with an airbag system that is un-configured and pooped their pants. I.e unlikely to work properly (if at all!!)

Given I trust Mercedes safety design I feel reasonably sure that if the passenger seat sensor is not working, then the worst case is that the passenger airbag won't work, but more likely that the passenger airbag will trigger even if no one is in the seat (depending what the lawyers said!).

But, if the system is un-configured, then who knows what will be working and what won't - since the controller is quite flexible in terms of what input devices (crash sensors etc) and output devices (airbags, tensioners etc) it has, and unless it is configured it can't really know.

Richard