PPD Sensor

[Luka]

Well, this is problem with my Brava 1,6 16V and this sensor on assistant driver seat have some problem. I think it's went off so is there any chance for front airbag to work without this sensor?
I will cut wires and put resistant element to simulate it, i done it also with lateral airbag and it's help. Now, it's problem with this sensor. Can it be "simulated" like lateral airbag's, because front Airbags is much important,and now they don't work, then lateral?

thank you

 

[Luka]

anyone?

 

[Owen]

yes its possible to simulate it. Check first that the seat sensor is actually working though. Its usually the connectors that are intermittent and cause the light to come on.
connect a multimeter to the wires coming from the seat sensor (blue and white i think).

I think a 100 Kohm resistor wired into the PPD module (approx the resistance of the sensor when there is nobody on the seat) will simulate the sensor. however, it may be better to simulate the resistance of the sensor when there is someone on the seat, but I'm not sure if the airbag ECU will detect a permanent low resistance as a fault either. Its also better to get rid of those connectors and solder the wires permanently to the PPD sensor module. there are three connectors, the two at the PPD module itself and another one on the side of the tunnel going to the airbag ECU.

Owen.

 

[Luka]

Well great, that was what i was looking for. So, i will simulate "empty seat", but first i will check those connections.
Thank you again and you really helped me...

 

[Luka]

And two more question.
If i make it to simulate as "empty seat", is then driver assistant airbag in function in case of some accident? Is it gonna work?
As you said, the resistance of empty seat is about 100 Kohm, so what is resistance with someone on it? Is it changeable due to weight of passenger and if it is, then what is resistance maximum in that case?

Thank you.....

 

[Owen]

well no its not going to work if you simulate an empty seat, better to simulate the resistance with someone sitting on it (unfortunately I had no help when I was trying to measure it ). It will be different depending on the weight, but I think the PPD module is just a simple comparator circuit with serial comms to the airbag ECU, so once the resistance is below a certain value, it should work ok. try 10 Kohms. I cant remember exactly where, but i think that other connector is under the carpet on the passenger side of the tunnel, you may have to lift the whole gearstick cover / center console thing to get at it..

owen.

 

[Luka]

Thank you and that precise info about resistance would be more then useful and for me and for the others also. I will try with yours suggestion also, Owen.
So, if someone with Brava/Bravo/Marea could measure sensor resistance of "empty seat" and "seat with passenger" and post it here, that would be great.
It could be easily measured, there is connector under passenger seat with two wires (blue and white). Of course, DON'T GIVE ANY CONTACT TO THE CAR WHILE YOU WORKING THAT.
Did you know the sensor on assistant driver seat cost 260 euro ?!!!


Thanks again

 

[Anonymous]

Well, i still didn't find solution for my problem, but i found something interesting on this topic. It is about Sensor for Airbag in Fiat Stilo and it's said:
The airbag ECU is sending out a square wave oscillation signal to the seat sensors and there are multiple sensors across the seat. Capacitance change means a change in the square wave to a point where it triggers the airbag ECU to "OK to fire when necessary"

With a simple pressure sensor in the seat the airbag system dosn't know whether there's an adult there on the seat or just something heavy like shopping so it might deploy an airbag needlessly in a collision. But a person has capacitance which can be measured between two electrodes in the seat bum area contacting their body and give an indictation of presence and size.


So, does this mean that it's impossible to put "static" resistance as i planned to simulate this sensor on my Brava? On Stilo, it looks like that, it's impossible!

Thank you