General Anyone with a spare OCS sensor connector?

[Morty Mort]

Well, I'm so tired of the OCS sensor problems now, that I've bought a seat simulator from Germany. This will override the airbag system OCS sensor, and respond as permanently occupied. It can still be shut off with the key though. The mat costs over 3000 NOK (about 300 GBP with todays currencies). Norwegian prices are quite high as many of you are aware of.

It is the baby seat that has destroyed it, and buying a new mat is no point, until I'm done making babies.

But the simulator comes without the grey connector (from the cushion), so I'm asking if anyone has this one. The dealers here looks like big questionmarks when I tell them my plan. OCS? What is that? In a Stilo? No it doesn't have it! What? Stilo? Is it a Fiat? Grey connector?

So you see that's why I ask overseas. If not, could anyone buy the damn connector and send it to me?

Regards, Morten.

 

[Deckchair5]

Why not cut off the existing one and use that? I doubt if the connector is available to buy separately but a few owners may have old ones lying around they could send you. I wish I hadn't thrown mine away.


This is the signal from a working OCS so no chance of a simple resistor or diode type simulator but if you can replicate this signal then you could make your own simulator for maybe a few pence of components

Unless I'm mistaken, with the airbag failure warning on then none of the airbags will go off and anything has to be better than that

 

[Morty Mort]

Why not cut off the existing one and use that?

That's what the German company tells me to do. I just had the idea that I'd assemble everything first - like plug and play (that rarely works).

This is the signal from a working OCS so no chance of a simple resistor or diode type simulator but if you can replicate this signal then you could make your own simulator for maybe a few pence of components.

When it comes to buildings and construction I know what to do, but when fiddling with mr. Ohm himself I am clueless.

Here's the company: Air-Com Airbagsteuersysteme. www.airbag24.de. They send worldwide, handle English/American excellent, and have a very helpful staff. I did the order through e-mail, and I had several payment options (like PayPal).

 

[Deckchair5]

There's only 3 wires to the connector- 12v positive / negative and the signal wire so it'll be easy to wire in the simulator. It simulates an adult in the passenger seat all the time,as you know, but that's better than no air bags working on the car at all and you can still turn the pass airbag off as normal

There is a solution for those in construction and building too. There is?

The OCS is two sheets of thin plastic bonded together with a few load cells stuck in between the sheets. The more the load cells are depressed the greater the resistance and with a bit of quick calculation the ecu in the OCS can work out the weight and just where the weight is by the size and load distribution of your backside. Then it tells the airbag ecu what a Lardass you are!

Anyway, what seems to happen is that these springy loadcells gradually break the bond between the sheets and then there's no resistance at the load cells and it all ends in tears

So, if you simply bond a flexible but stiffer plastic sheet on the OCS then the ecu stops crying and everything works again but you have to make sure everything is dead flat whilst it's bonding so you need something like your entire porn collection on the top for the night

Remember it'll take 3 clear starts for the warning to clear

 

[T14086]

Unless I'm mistaken, with the airbag failure warning on then none of the airbags will go off and anything has to be better than that

Only the affected airbag/circuit wont work unlike other fiats where whole system is disabled. I remember this cause numanR & I were arguing about it...he was right

 

[Deckchair5]

Ah! Cheers for that T1!

 

[Morty Mort]

There is a solution for those in construction and building too. There is?

Work with people rather than materials.

Then it tells the airbag ecu what a Lardass you are!

Well, I did gain a few kg during summer, but I'm working on lifting them up to the pecs now. Anyway, I rarely sit in that seat...

... so you need something like your entire porn collection on the top for the night

Right now that collection is digitalized, and wheighs minimal. You'll have to think of something else. Bricks perhaps.

Just to mention. Babyseats are OCS mat killers.

 

[mhowse]

Just a thought for any electronic wizards about but if it a case of a resistance measurement then if folk had a problem would there be a way of finding the size of resistor needed for specific weight ranges and figuring how to connect them in with removable connectors maybe something like 5 to 10 stone,,10 to 15 stone and so on ,
would make a cheap fix if it was possible and just a quick trip down to the local maplins for the resistor needed..may not be as simple as that but just had me thinking when deckchair mentioned resistance.

 

[Deckchair5]

The load cells are the resistance but then it checks out the capacitance so it can differentiate between a dead weight like a bag of shopping or a human. All clever stuff

Yes baby seats or anything heavy or sharp on the ocs is not good

 

[john55]

The load cells are the resistance but then it checks out the capacitance so it can differentiate between a dead weight like a bag of shopping or a human. All clever stuff

Yes baby seats or anything heavy or sharp on the ocs is not good

As far as I can tell from testing one of these mats, it doesn't use a resonant circuit to measure capacitance. This is a very inaccurate method anyway and can not tell the difference between shopping and a person, let alone a child and an adult. It measures the resistance of the load cells only, and expects to see a pattern like a persons bum in the cell matrix. The main way it knows if it is a person or not is if the seatbelt is plugged in. The passengers airbag will not fire if the seatbelt is not worn.

You can not replace the mat with resistors as each mat is calibrated to the controller after it is manufactured as the sensors are not accurately manufactured. There is also a second set of wires in the mat which act as a feedback, to check that the mat has continuity throughout and no broken wires exist. If either a break in the main mat, or the feedback circuit occurs then the controller assumes a fault. The feedback loops are capacitively connected to the main mat so not to affect the reading of the sensors. Maybe this is where you are getting confused about capacitive sensing.

The mats can fail in many places (mine had broken connections in the area where it bends round the front edge of the seat).
I tried to delaminate it and repair it, but it was hopeless as although only one track was probably broken, when I tried to delaminate it, other tracks were pulled away / broken in the process as they had become very fragile.

The only way to replace it is either with another sensor, or an emulator.

I hope to have an emulator working soon as I now have a working mat to test with in my car.

Deckchair, do you have any more traces from the OCS, with different weights etc? Also, that trace is half from the Airbag ECU, with the OCS only sending a response to the Airbag ECU's request. It does not but data on the bus by itself, only when it receives the correct request. What is the frequency of the data packets? I can see from the trace that they are 14400 baud, but do you know any more about the format?

 

[Deckchair5]

As far as I know it uses fuzzy logic to work out the mass and distribution of the load in the seat. Each design of OCS is different and they keep their patents a well guarded secret.


This is the only other OCS trace i took which doesn't show a whole lot apart from the sampling done approx every sec with the airbag ecu interrogating the OCS for changes


If it's any help here's some other info on how the OCS works although this isn't a Stilo system. This shows how it detects not just the mass but how it's distributed. Deflection bending of the flat strip sensors give an indication of load distribution





The next step is an infra red or grey scale camera to detect passenger size and position

 

[Argonought]

The passengers airbag will not fire if the seatbelt is not worn.

I never realized air bags are disabled if the seat belt isn't worn.

Still, I suppose you get an unimpeded exit from the car that way

 

[Deckchair5]

Yes that's right, the majority of fatalities by airbags in the early days were because the person didn't have their seat belt on. The seat belt is the first item of safety equipment and the airbag relies on the person being restrained by the seat belt first. Without it, the person would be flying into an inflating airbag and that's not nice at all as it would be like a sledgehammer. The airbag has to be expanded and already deflating when the person hits it.

So if the seat belt isn't fastened then no airbag

 

[Morty Mort]

Hello again.

Just to summarize (or whatever it's called) this thread.

The simulator was mounted this weekend. And how wonderful everything is now. The beeps stopped after the initial start. The red airbag failure lamp lit up immediately, but vanished after 5 seconds. And it hasn't appeared since. The simulator is about the size of a matchbox, and is now ziplocked to the seat's frame.

No fiddling at all. Just levered out the connection block holder under the seat, unclipped the grey one, cut the wires from it (no need for battery disconnection either), brought it inside and soldered the wires from the simulator to the wires from the cut-off wires from the grey block. They even had the same colors so you have to be a pure idiot to mess them up. Back to the car to connect the grey male/female blocks to each other again, mounted the simulator (it has long wires) and levered the connection block holder back under the seat.

So now, everytime I start the car, the orange warning light flashes for a second, to tell someone is sitting next to me. Just as it used to do when someone sat down there - or I put a grocery bag etc. there. Everything works well.

M.

 

[Stilatos]

why do you put your child in the front and not in the back seat and avoid this problem of destroying the matt sensor? plus in the back they have iso connectors i think their called to easily connect to baby seats its sort of a plug and play thing between the upper and lower part of the seats where the seatbelts come out of.

 

[Morty Mort]

Because I'd like to know what's happening to the baby, and see how he/she is doing. Easy manouver of the soother or bottle, and if you knew how much calmer a baby is when it can have some sort of contact with you, you'd never put it in the rear seat.

I know the ISOfix, as I use them for my kids now (two chairs). It's a fantastic thing. Click on click off. ISOfix for babyseats are nightmares as the seat's base takes up extremely much space.

Morten - the best dad in the house (I got a pair of underwear from my son stating it). :slayer:

 

[stheo]

Hi Deckchair5,
I'm a electronic engineer and I'm trying to build a sensor emulator for my Fiat Stilo.
The circuit is quite simple, a little PCB with a microprocessor. I can't find the sensor datasheet, I need to know how this works and what kind of signal to simulate.
Where did you find the information about the first graph? can you help me? If I have the real signal to analise, I sure will be easy to emulate this.

Thanks,

Stheo.