R171 SRS Seat Sensor - Connector, and Could The Front SAM Be The Culprit?

[E55BOF]

I'm trying to remove the passenger seat cushion from my '05 SLK to get at the SRS seat sensor. I recently replaced the heater motor and fan, which entailed lying half-on the seat for an extended period, and next time I started the car the SRS warning light came up. My iCarsoft says it's open circuit to the seat sensor. I can cancel the stored code, but it comes back immediately the car is started up. I suspect I've displaced the wiring under the seat when lying on it. Buckling up the seat belt makes no difference.

Three questions, then. Firstly, could the culprit be the front SAM, which has been playing up recently?

Secondly, I assume the sensor loom is the yellow one going up to near the centre front of the seat cushion?

Thirdly, the yellow loom has a very strange (and small) yellow connector at the end which goes to the plug unit at the front of the seat base. I've never seen one like it, and I can't work out how to release it at all. Does it pull straight out, or slide off sideways, does anybody know?

 

[Dodipops]

Won’t be front Sam related, yes it’s the yellow connector for srs components and no it doesn’t just pull, you have to slide the inner part of the connector then separate.

 

[Flyinspanner]

Disconnect battery before playing with any yellow wires... you wouldn’t want to blow any bags/tensioner

 

[E55BOF]

The advice I've been given is that there's no need to disconnect the battery, but to make sure the key is out of the ignition so there's no possibility of switching it on.

The SRS sensor in the seat is already disconnected; once I find out how to free the lead from the multi-plug it's held in, I can take the seat cushion out of the car and get at the actual sensor.

 

[pmcgsmurf]

I always disconnect the battery when dealing with any of the SRS or airbag connectors just to be safe.

As mentioned you need to slide the connector part before removing, I see a lot of youtube videos on airbags where they just pull them hard!

 

[E55BOF]

There are two little 'oles on the wire side of the actual plug part; a tiny screwdriver in each to release the tiny catches, and away it comes. I gave it a lot of thought before finding that out; past experience with the multitude of different tiny, fragile plastic electrical connectors Mercedes uses has resulted in breakage, and I want to reuse it...

I want to reuse it because having found out the cost of a new seat occupancy sensor, I'm going to fit a bypass emulator instead. The passenger airbag will be permanently live with the ignition on, but since there are no conceivable circumstances in which I will ever carry a passenger who cannot wear the seatbelt in that car, that's not a problem.

 

[wongl]

There are two little 'oles on the wire side of the actual plug part; a tiny screwdriver in each to release the tiny catches, and away it comes. I gave it a lot of thought before finding that out; past experience with the multitude of different tiny, fragile plastic electrical connectors Mercedes uses has resulted in breakage, and I want to reuse it...

I want to reuse it because having found out the cost of a new seat occupancy sensor, I'm going to fit a bypass emulator instead. The passenger airbag will be permanently live with the ignition on, but since there are no conceivable circumstances in which I will ever carry a passenger who cannot wear the seatbelt in that car, that's not a problem.

It looks like I need a passenger seat sensor in my 2011 R172. The one and only MB dealership in HK quoted me over £1000 for the sensor and over £300 to fit the sensor. I managed to order a replacement seat sensor from a UK main dealer with an ebay shop for under £200 will be attempting to fit this before my MOT is due in October.

 

[wongl]

Not fancy bending over an extended period removing the seat out of my R172, I paid a mobile mechanic to remove the seat and to replace the seat mat sensor.

Upon refitting and clearing all error codes in the R172, the airbag warning light remains in a flashing state. A search of the internet suggests that the SRS module was in an unlocked state and I manage to resolve this using Xentry to reset the SRS module.