Hello everybody.

I want to install a facelift steering wheel to my pre-facelift model. (Fiat 500 of 2012)

Problem: Fiat 500 2007-2015 have driver and passanger airbags with 2 stages.
Models after 2015 only have one stage.

When I read the ecu parameters of body computer and airbag ecu (continental)
I see the paramater "Driver Airbag second stage availabe yes/no" but I can change it only in the body computer.

When i connect to the airbag ecu i only can read parameter but not change.

the question is now, how can I change the necessary parameter at the airbag ecu?

When the airbag ecu is resettet to naked (which some special companies can do).... does it get its configuration from body computer ?

Or is there another software / trick to rewrite the configuration on airbag ecu.

The software I have used is alfaobd and multiecuscan.

with alfa obd I can change the airbag to "onestageonly" in the body computer by changing the car configuration. After that I did a proxi alignment but the airbag ecu does not accept the parameter to change......


Any Ideas?

Some other earlier models also have single stage as I have mistakingly bought old style single stage drivers airbags twice so I imagine it must be possible.

I was looking at this yesterday in MES as my new 2009 car has a slightly worn steering wheel. I’ll have another look now to see if it can be disabled as I would quite like to put the new style wheel on. What I did realise though is that the old airbag is a different shape to the new one so my idea of using the original airbag is a no no.

I’ll report back on this as you can enable and disable many things. I disabled the front fogs on this one as I intend to take them out for a future project as this car is going to be a cheap car for someone so I want to claw back as much as I can.

Why bother putting the airbag in?

If you want to play around with any safety computer stuff then you have absolutely no idea if the airbag is going to deploy in the event of an accident.

jrkitching is this topic even something that Fiatforum wants to be hosting?

306maxi said:

If you want to play around with any safety computer stuff then you have absolutely no idea if the airbag is going to deploy in the event of an accident.

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:yeahthat:

In spades.

306maxi said:

@jrkitching is this topic even something that Fiatforum wants to be hosting?

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I've made my views clear on this before; this post summarises my own take on this matter.

This is an old, old article, but it's as relevant today as it was when it was written, and there's nothing in it I'd disagree with.

Fiddling with an airbag system you don't properly understand on your own car might just get you a Darwin award. Fiddling with one on a car you subsequently sell on could cost an innocent person their life.

Even manufacturers get it wrong sometimes - there was a major recall on the 500 due to the possibility of incorrect airbag deployment back in 2010.

But it's an open forum, and folks are free to post what they choose. I'll censor a post if it's abusive, defamatory, illegal or otherwise breaks the forum rules, but if I censored posts just for being stupid, I'd be here all day.

Why someone would want to risk messing with one of the most important safety critical systems on the car just for the sake of fitting a different steering wheel is beyond me.

Have I missed something here? He said that all airbags on later cars are single stage now? If that’s the case how is installing a more modern steering wheel with accompanying single phase airbag wrong?

typecastboy said:

Have I missed something here? He said that all airbags on later cars are single stage now? If that’s the case how is installing a more modern steering wheel with accompanying single phase airbag wrong?

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The OP is proposing to install a new type steering wheel with single stage airbag to a pre-facelift 2012 car with a two stage airbag.

jrkitching said:

The OP is proposing to install a new type steering wheel with single stage airbag to a pre-facelift 2012 car with a two stage airbag.

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Yeah, I get that, but apart from maybe having to change the airbag ecu too, I can’t really see a problem.

typecastboy said:

Have I missed something here? He said that all airbags on later cars are single stage now? If that’s the case how is installing a more modern steering wheel with accompanying single phase airbag wrong?

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Amazingly wrong.

It would be safer to lower a car by cutting the springs while the springs are compressed.

What voltage does the new airbag need to fire? What voltage does the old airbag need to fire? Is the safety computer compatible with the new airbag?

If the OP goes ahead with this fool’s errand, I do rather hope they disclose this modification to their insurer and any subsequent purchaser and explain what they actually did.

I’ve been on here for something like 10 years and this is the most idiotic thing I’ve ever read on here. I work for a well known car company in their electrical engineering department and things like this are NEVER as simple as they seem. Airbags are designed to work in conjunction with other airbags, I’ll wager that if Fiat have changed the airbag in the wheel, they’ve probably also changed the curtain and seat airbags. Putting a random airbag into a system that wasn’t designed for it is absolutely moronic, you could be creating a clash of airbags, you could create a hole in the airbag system where your head could go through and impact something and kill you.

I’ve been working intensively on one project for the last 16 months, if someone gets into a serious accident in one of our cars that we’re delivering to customers at the moment then I can hand on heart say that the bags will fire and do their best to keep the occupants safe. No one knows if a new airbag in an pre-facelift 500 will actually fire, let alone do the job it is designed to do.

Actually that’s a very good point, the passenger airbag for definite and I’m sure some of the others are dual stage so of course if you disable one, you disable them all.

Could you please enlighten me on the two stage air bag deployment ,dose this mean in a not so serious crash the bag is only partially inflated ??

Michael Dranfield said:

Could you please enlighten me on the two stage air bag deployment ,dose this mean in a not so serious crash the bag is only partially inflated ??

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Basically yes.

https://www.firehouse.com/rescue/article/10531885/dualstage-airbag-systems

A two stage bag is preferable tbh. It also gives you the option of a second firing if you hit another object or objects.

typecastboy said:

Actually that’s a very good point, the passenger airbag for definite and I’m sure some of the others are dual stage so of course if you disable one, you disable them all.

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I don’t want to sound patronising, but here goes.

In the last 16 months I’ve learnt that modern cars are far more complicated than I ever could have imagined in my wildest dreams.

We have one engineer dealing solely with the window/door ECU.
We have another dealing with the spoiler ECU...
We have one engineer that deals purely with the roof console.

Think of the complexity of those fairly simple things if you have to get an engineer whose abilities faaaaar outweigh yours and mind for 40 hours a week to work on those systems. Those are “simple” systems too, nothing crazy like the engine, safety computer, ESC/ESP ECU...

I do basic work on my cars, servicing, and removing and replacing simple bits, but tbh anytime you’re playing with anything electronic and safety critical it really should be done by a qualified and trained person.

Interesting article and it points out what I was already thinking, a deployed airbag then does not mean a safe air bag as it could deploy for a second time when it already appears to have been fired.

I've got to ask, why on earth did Fiat change from dual stage airbags to single stage?!

puntofan01 said:

I've got to ask, why on earth did Fiat change from dual stage airbags to single stage?!

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We can only speculate.

It could be cost over safety.
They new single stage bag might perform every bit as well as a two stage one.

It could be pretty much anything, without talking to the engineer responsible or someone working on the project there’s no way of knowing for sure.

Everything Maxi has said and more...

They don’t usually just turn off a stage of the airbag system to fit a different airbag, the airbag module may be the same but the software coded to it will be different at the factory, this isn’t like coding in and out features on the body computer, criticalsafety systems are designed to work together so as pointed out by Maxi a dual stage airbag will work differently with the curtains, pretentioners and other safety systems.

Engineers don’t just switch things on and off and then see what happens they have to produce reams of paperwork and analysis of all the components before changing something.
Probably ten times as much with airbag systems.

When I worked in engineering which was seriously high precision stuff you couldn’t so much as change one 47ohm resistor for another one without extensive testing and analysis kill half a rain Forrest with paperwork and then run dozens of tests to make sure that 2pence resistor was going to work and give predicable reliable results.
We would pour over this stuff for hours.
That’s why R&D costs for a car can be in the billions.

In the case of dual and single stage airbags, a lot of it can be due to things like the car monitoring the weight of the driver, the position of the seat, if the seat belt has been used or not etc.

The only way you could safely change the airbag for a totally different type and design and still be sure it would work, would be to change everything else relating to that system, or else you could get hit with the full force of a deploying airbag in the chest or face when the car should have only deployed one stage.

We’re not messing about when we say this modification really could kill you, you’d be safer removing the airbag entirely

This came up at work today.

The thinking was that there was no way to guarantee that the bags would fire with mismatched bags and a safety computer with what is almost certainly the wrong software for the bag/s in use.

The biggest concern was airbags which could either potentially clash with each other and impinge on the space the passenger should be in, OR leaving a hole in the wall of airbags and having your head hit the interior of the car and causing serious injury or death, which was pretty much what I’d thought.

This is from people whose job it is to design and put cars into production.