W210 - disable passenger side SRS? - PeachParts Mercedes-Benz Forum

m1tch · #1 01-29-2016, 07:57 AM

Hi all,

Just pulled the passenger seat out the car, its 100% manual so has just 4 bolts and the connectors for seat occupancy. The SRS light is on due to the seat not being connected to the car, mine is a pre facelift model so I believe if I plug the seat back in it should recheck the system and turn off the SRS light (my seat is 100% working).

Just wondering if there was any way of just turning off the passenger side - usually there is a key somewhere that you can turn that side off if you for example had a child seat installed.

bsharp8256 · #2 01-29-2016, 01:37 PM

While researching how to fix the SRS light due to a bad seat sensor in my W220, I found that most people install an emulator that just plugs in where the seat does and fools the system into thinking it's there. They're cheap and seem to be widely available online, but it seems that some have quality issues (they're basically all made in China...) so I'd do my research before buying. I plan to fix the actual sensor, so this didn't apply to me, but I know the objectives for our respective cars are different

PS, I love your build thread and I'm excited to see what you do with it!

jay_bob · #3 01-29-2016, 02:43 PM

You'll need the emulator if you are running without the passenger seat.

This model has the Siemens BabySafe system. It used an RFID tag in the car seat and a reader in the seat occupancy sensor in the bottom cushion to do the disable function.

The seat sensor is a large mat made from two pieces of Mylar with conductive traces. If you've ever taken a calculator or remote control apart it's just like that. There are also paths that form the RFID antenna around the perimeter. On the forward end of the mat is the box that holds the RFID electronics and receives the cable from the seat base.

You could conceivably remove the sensor assembly from the seat, tuck it under the floor mat, and plug it back in. The sensor pad is about the size of a letter (A4 for you guys over there) sheet of paper.

I had to remove my sensor and repair the cable between the sensor mat and the yellow connector. The original cable was made from wire with a low strand count and broke from constant flexing. A very common theme in MBs for many years (and others - I had a Honda with pop up headlights that had the same issue). I spliced a length of 3 conductor heavy duty extra flexible cable in between the mat and connector and it's been working for a couple years now.

sixto · #4 01-29-2016, 11:34 PM

Can SDS disable the passenger airbag and clear the warning light?

Sixto
83 300SD

jay_bob · #5 01-30-2016, 07:18 AM

I seriously doubt it will let the error clear if the system is not intact.

OP is making a race car, which is why he is trying to shed weight by losing the passenger seat.

sixto · #6 01-30-2016, 08:12 PM

If it's a race car, remove the SRS bulb

Sixto
83 300SD

m1tch · #7 01-31-2016, 10:40 AM

Quote:

Originally Posted by sixto

If it's a race car, remove the SRS bulb

Sixto
83 300SD

The UK MOT requires for the light to light up on startup and then go off, same as the airbag light etc. Plus with the SRS light on there isn't an airbag active - not ideal when driving over to the track.

The car will be a sleeper, its not going to be stripped out, all the interior I have removed can be replaced within about 15 minutes and around 8 bolts.

jay_bob · #8 01-31-2016, 12:11 PM

In that case I would get a seat switch emulator, or else find a seat switch from the wrecking yard and put it under the carpet. When you pull the sensor plug when taking the seat out, plug it to the substitute. Just be sure the key is off, and the car will be none the wiser.

Fortunately this is a non latching alarm and will self reset when everything is normal. Not so much on the later models.

sixto · #9 01-31-2016, 01:33 PM

x2. I wouldn't even mess with an emulator. Get the switch from a seat. Maybe it can be removed from the seat you're leaving at home without destroying the seat.

Sixto
83 300SD

m1tch · #10 02-01-2016, 02:39 AM

Quote:

Originally Posted by jay_bob

In that case I would get a seat switch emulator, or else find a seat switch from the wrecking yard and put it under the carpet. When you pull the sensor plug when taking the seat out, plug it to the substitute. Just be sure the key is off, and the car will be none the wiser.

Fortunately this is a non latching alarm and will self reset when everything is normal. Not so much on the later models.

Thanks for this, before I pulled the seat I disconnected the battery anyway - don't really want any of the airbags deciding they want to deploy!

Thanks for the note about the non latching alarm, I read somewhere that the earlier pre facelift model like mine just check the system when it started up rather than it latching on and needing a STAR reset etc.

If anyone is curious, the OEM manual cloth seat weighs around 25kg - I have removed around 185kgs from the car so far just by unbolting 6 of the seats lol. The spare wheel is very very heavy though as its a full sized steel spare, I have removed it and will just run with one of those tyre can things to and from the track.

jay_bob · #11 02-01-2016, 10:51 AM

Quote:

Originally Posted by sixto

x2. I wouldn't even mess with an emulator. Get the switch from a seat. Maybe it can be removed from the seat you're leaving at home without destroying the seat.

Sixto
83 300SD

Removal of the sensor requires disassembly of the seat. I had to do this to mine, it was fairly involved and took the better part of an afternoon to remove, repair the cable, and reinstall.

m1tch · #12 02-03-2016, 02:28 AM

I have reinstalled the seat back in, its only 4 bolts and the seat connectors, would rather have airbags than the 0.05 of a second that the 25kgs would work out to take off the 1/4 mile time!

I can see that there are 2 connectors, one seems to be slightly frayed but the other was fine - which plugs are under the seat, there is the seat occupancy one and....?

jay_bob · #13 02-03-2016, 06:24 AM

...seat belt buckle switch.

Come to think of it, that switch being absent would likely have given trouble. They often put a shunt resistor in there to verify the switch presence.

m1tch · #14 02-03-2016, 07:02 AM

Quote:

Originally Posted by jay_bob

...seat belt buckle switch.

Come to think of it, that switch being absent would likely have given trouble. They often put a shunt resistor in there to verify the switch presence.

Hmm I see, I think the other issue is that the seat also provides the bottom mounting point for the seatbelt - the MOT requires all belts to work correctly if fitted (even if there isn't a seat). I will just keep the seat in there for the time being, its not a massive reduction in weight.