Technical Airbag system diagnosis

[Zekarn]

Hello everyone,

I am currently facing an issue on my Fiat DOBLO version my doblo 2005. When dialing with the airbag console I retrieve this code :
"3C - Chock sensor front left | Open line | Intermittent"
that point to my front sensor. After looking in the official fiat documentation I have find that this sensor is a variable resistance (K175, see docs below). When I take the resistance of my sensor I found OL. However, the fault is intermittent, which seems to indicate anything else. Can anyone with a similar working sensor take his internal resistance in order for me to test with a spare resistor ?

Thanks you all in advance

Docs :
Electrical diagram :

Home Page

aftersales.fiat.com

Components location :

Home Page

aftersales.fiat.com

 

[the green vanper]

Hello,

Why do you want to fool the system and not repair it?

It's a security system, very important. What if the airbag explodes during driving after you've fooled it?


What have you read the errors with? MultiEcuScan? OBD? or any other non-FIAT dedicated software?


OL means over the limit, perhaps you need to adjust the range on the multimeter?

 

[Zekarn]

Hello,

Why do you want to fool the system and not repair it?

It's a security system, very important. What if the airbag explodes during driving after you've fooled it?


What have you read the errors with? MultiEcuScan? OBD? or any other non-FIAT dedicated software?


OL means over the limit, perhaps you need to adjust the range on the multimeter?

Hello

The idee was not to fool the system while driving, only to see with multiECUscan if the fault is gone. The airbag shouldn't explode at stop state, even with ignition on. More than tkat, it is the standard procedure for diagnosis of others airbag components as explain on the aftersales fiat website

The other idee was to know if my sensor is defective or if I have another issue with my system

I use multiECUscan with VAG-COM interface and red adapter to dial with airbag computer

I have an auto range on my multimeter, without changing any parameter on it I have been able to mesure ~2MΩ on my skin but I have OL on my sensor

 

[the green vanper]

Hello

The idee was not to fool the system while driving, only to see with multiECUscan if the fault is gone. The airbag shouldn't explode at stop state, even with ignition on. More than tkat, it is the standard procedure for diagnosis of others airbag components as explain on the aftersales fiat website

The other idee was to know if my sensor is defective or if I have another issue with my system

I use multiECUscan with VAG-COM interface and red adapter to dial with airbag computer

I have an auto range on my multimeter, without changing any parameter on it I have been able to mesure ~2MΩ on my skin but I have OL on my sensor

Sorry, I have understood that you want to replace the sensor with the resistor permanently.

MES should give you the proper error code, other readers sometimes point in the wrong direction.

One more thing: remember to disconnect properly the battery before you play with the pretensionners connectors to avoid any damage to the airbag module. They are very sensitive and prone to damage.

Good luck with the diagnosing

 

[Zekarn]

Hello,

Sorry for the delay

Update on the situation of my fault
Since may I have do more research and have found another crash sensor but after replacement it doesn't change anything
I have also soldered the cables under the driver seat as they are prone to cause this issue, but without success
I have talk with a work colleague who have worked in automotive parts repair and tell me that others point of failure on every cars can be inside the belt pre-tensionner and the spiral cable. He told me that the airbag tehnology is a single loop taht cross everything in the car and that a fault shown can be on the wrong element
After checking FIAT procedures I have order a set of resistors to try to replace every airbag component with resistors (except for the crash sensor who seems to be a switch) but it is for diagnosis ONLY and not to go on open road !

Therefor I have more and more reasons to think that the vehicule that I have in my possession have deal with a front crash (ECU changed, potentially motor too, the entire front end and right front wing and front driver belt have an abnormal behaviour)) and I have electrical issues with the passenger window who blown a fuse every now and then

Join to this message a report of MES if you want to check
I will forward informations as soon as I have try this