Technical Airbag Electrical Fault

[tommyc123]

Hi all,


My girlfriend has had her Fiat for about a year now, and she’s recently started getting a few of the common warning messages:

• Fuel Cut-Off Unavailable
• Flashing mileage
• Start/Stop Unavailable
• Airbag warning light on

She took it to an auto electrician who scanned it and said he couldn’t communicate with the airbag module. He also had a quick look at the rear wiring loom near the boot and said it looked okay at a glance.


She’s understandably a bit worried about driving it now with the airbag potentially not working. From what I’ve read, it seems like it’s 50/50 between a fault in the airbag ECU or the rear wiring loom.


Just wondering:

• Is it an easy job to remove the airbag module?
• Are they coded to the car (i.e., would a replacement need to be programmed)?
• Has anyone had this issue before and had success sending the module off for repair (e.g., through eBay airbag module fix services)?

Any advice or shared experience would be greatly appreciated!


Thanks in advance!

 

[bugsymike]

Hi all,


My girlfriend has had her Fiat for about a year now, and she’s recently started getting a few of the common warning messages:

• Fuel Cut-Off Unavailable
• Flashing mileage
• Start/Stop Unavailable
• Airbag warning light on

She took it to an auto electrician who scanned it and said he couldn’t communicate with the airbag module. He also had a quick look at the rear wiring loom near the boot and said it looked okay at a glance.


She’s understandably a bit worried about driving it now with the airbag potentially not working. From what I’ve read, it seems like it’s 50/50 between a fault in the airbag ECU or the rear wiring loom.


Just wondering:

• Is it an easy job to remove the airbag module?
• Are they coded to the car (i.e., would a replacement need to be programmed)?
• Has anyone had this issue before and had success sending the module off for repair (e.g., through eBay airbag module fix services)?

Any advice or shared experience would be greatly appreciated!


Thanks in advance!

Sounds like several different issues. Flashing mileage and Start/Stop Unavailable are often battery of earthing issues.
Air bag module is the BCM (Body Computer Module) which unless it is a brand new/virgin one will not work from a different car. Even a new one will need "proxi alignment" where diagnostic tool garage Snap On or many Fiat owners on Forum use MES (multiecuscan tool) on their lap tops etc. can do that job.
Given the other issues it may be worth having someone with that tool check what errors are stored on computer and go from there.
As a start, if a wrong non stop/start battery has been recently fitted or if you have a bad earthing issue that would be the first things to check.
There are several postings on Forum regarding that which may help guide you.

 

[the green vanper]

I'd totally agree with @bugsymike to check the battery and the earthing straps / points. And replace the main earth cable with a good quality copper one. I'm buying one cut to length from a welding hardware store. They should also be able to add the terminals on the ends.

Here's the eLearn doc on the earths from the 2008+ Grande Punto, I assume the main cable is the same.

 

[varesecrazy]

Worth noting that Flashing mileage COULD be a Blue and Me failure..

Tends to flatten the battery,

and Low Battery voltage can trigger Odd Warnings

Where is the car based?

 

[Phelanpa]

definitely replace the earthing strap going from the negative battery to the gearbox engine. Costs about 15€ and you can do it yourself easily.
Then check all rear lights are working including reverse and fog lights, check rear windscreen de mister, rear wiper and washer. Check boot opens. If all these work then your rear loom to boot hatch is ok. So you can discount the rear loom - otherwise get in there and sort broken wires which are very very common.

Now you are on to the airbag module. It’s a small unit typically located under the heater bolted to the gearbox tunnel. Three bolts and disconnect the two wiring connnectires and it comes out. It’s a bit tight but with spammers and sockets yiu can do it handy enough. Take
Out the old one - disconnect the battery first - get the reference numbers - buy a new one on eBay and make sure it does not have crash data on it - it’s plug and play, no pairing needed - just need to
Match the numbers. Clean the Earth wire contact while you are in there.

All of the above is vased
On my 2008 Fiat 500 experience
But I reckon the Punto will be pretty similar

 

[bugsymike]

definitely replace the earthing strap going from the negative battery to the gearbox engine. Costs about 15€ and you can do it yourself easily.
Then check all rear lights are working including reverse and fog lights, check rear windscreen de mister, rear wiper and washer. Check boot opens. If all these work then your rear loom to boot hatch is ok. So you can discount the rear loom - otherwise get in there and sort broken wires which are very very common.

Now you are on to the airbag module. It’s a small unit typically located under the heater bolted to the gearbox tunnel. Three bolts and disconnect the two wiring connnectires and it comes out. It’s a bit tight but with spammers and sockets yiu can do it handy enough. Take
Out the old one - disconnect the battery first - get the reference numbers - buy a new one on eBay and make sure it does not have crash data on it - it’s plug and play, no pairing needed - just need to
Match the numbers. Clean the Earth wire contact while you are in there.

All of the above is vased
On my 2008 Fiat 500 experience
But I reckon the Punto will be pretty similar

All good advice from @Phelanpa , my only query is on the 2010 Fiat Punto Evo I fitted a brand new Fiat BCM which is as described mounted as mentioned under heater on transmission tunnel.
The reason I had to replace it was a poor repair by previous owner on the passenger seat occupancy sensor had bypassed the resister and shorted the old BCM. After fixing all that and replacing the BCM the dash error lights were all still there until I used by my friends Snap On Zeus diagnostic tool to "tell" the new genuine BCM to recognise all the Air Bag Sensors etc. connected by running the "proxi alignment " program, after which I then deleted all existing error codes on cars system and vehicle has been fine since over 4 years.
Out of interest this is the old unit. Don't ask why I still have it.

 

[Phelanpa]

And just to add. If yiu don’t have a fancy diagnostic tool, get yooursel a copy of multiecuscan, download it to your laptop and buy the necessary ODB2 adaptor - the site will tell you clearly what colour adaptor you need. It’s pretty cheap for what it will do for you and works on all Fiats - invaluable for reading and resetting warnings on the dash. Also, if the mileage is still flashing at the end of all this yiu can do A proxy alignment to stop that - all sounds Pretty fancy but it’s just a couple of menu options on multiecuscan.

And on the Fiat 500 2008 it’s only the airbag ecu located under the heater for sure. but no doubt other fiats may have the BCM fitted here. You’ll just have to do a bit of research.