Hello
I am new here. Would you please give me some guidance?
I have airbag light on in my Citroen Xsara Picasso, year 2002, ECU: autoliv 602327400
I have Haynes wiring diagram, but I am not sure if it is complete or if something is missing.
Anyway, I disconnected battery and opened the airbag ECU connector and by digital mutimeter from the connector I measured resistances to
- each of 4 airbags (left, right, left side, right side) all OK, below 1ohm to 3ohms, as well as 2 belt tensioners, slightly higher, 2,8-3,2ohms. In my understanding these are OK.
- airbag sensors / 2 pieces: this resistance is in one way several kOhms, in another way about 600ohms. So connection seems to be OK, BUT WHAT ARE THESE SENSORS FOR and where are they located? Can I somehow bypass them in order to test whether the sensor is faulty or not? According to common discussions the airbags can be bypassed for testing by 1-3ohm resistor, but I guess that the sensor is not so simple.
Up to here, the wiring diagrams seems to make sense, but I am not sure, if something is missing?
I have a OBD2 / Bluetooth dongle and have tried many ANdroid apps to find out the airbag fault codes with no success. Almost all of them connect to the main ECU and give me some engine data, but nothing from airbag. Any hint, which app may work in this case? I woud not like to pay for the app just to see, that it is not working for me.
If all the sensors and bags OK, shoud the fault lamp go off, or do I need to reset it somehow? By OBD2 app or do I need more complicated tools / procedures?

Cheers!
John