Technical 2015 Ducato X250 Euro 5 Airbag and fuse dilemma

[growlybear]

Here goes, please bear with me as I need your advice!

So my airbag light came on, and ran MES which showed an Airbag ECU removed fault. Couldn't communicate with the Airbag ECU.

Did a Proxi Align, thinking that the config had become corrupted.
Airbag light off, odometer stopped flashing.

However, the body computer can now longer see the airbag.

There is no mention of a fuse in the Handbook, and fuse location 50 in the fuse box doesn't have a fuse fitted.
I managed to get the wiring diagram for the Euro 5 fusebox and airbag ECU, and F50 should have a 7.5A fuse.

So, if there is no fuse fitted and that is the problem, then why was it working until the fault was shown?
Could a fuse have popped out?
Has someone wired a separate ignition feed to the airbag ECU?
Should I fit a fuse and see?

What would you do?!!

Thanks for reading this and I really hope that it makes sense!

 

[spidermania]

What would you do?!!

Thanks for reading this and I really hope that it makes sense!

Highly unlikely a fuse pooped out. No doubt about it it's a serious issue when we are talking about airbags, you have no way of knowing if they will deploy in an accident.
I'm in the same predicament albeit from a different source. I'm waiting on a part now from the factory in Hiroshima Japan, eta is over a month. I'm hoping the young idiot who got into my computer didn't brick it.

My advice is to consult a professional, FIAT dealer or qualified private garage.

 

[HughJampton]

Originally you would have got a fault (and flashing odo) because the expected (in the config) airbag ECU couldn't be seen.
I would surmise that doing a Proxy Align in that state would reset the config to one without an airbag ECU present (and inhibit the flashing odo, as it now thinks it has everything it should). Result, no airbag, no error, not really a state you would wish to keep.
If so, the remedy would be to replace the ECU with a correct working one, and re-run an appropriate proxi align to add it.
I think the fuse is a red herring.
The above is not gospel, but it's certainly what I'd surmise with the process you've been through.

 

[growlybear]

Originally you would have got a fault (and flashing odo) because the expected (in the config) airbag ECU couldn't be seen.
I would surmise that doing a Proxy Align in that state would reset the config to one without an airbag ECU present (and inhibit the flashing odo, as it now thinks it has everything it should). Result, no airbag, no error, not really a state you would wish to keep.
If so, the remedy would be to replace the ECU with a correct working one, and re-run an appropriate proxi align to add it.
I think the fuse is a red herring.
The above is not gospel, but it's certainly what I'd surmise with the process you've been through.

Thank you. Your comments are aligned to mine. However, the airbag ecu must be fused somewhere?

I bought the camper 5 months ago and it had a new airbag ecu for the mot just before I bought it (£550). I'm trying to check all options before I buy one in case there is an underlying problem that's wiping then out.

I guess the next thing is to disconnect the battery, wait 10 mins and then remove the ecu. Refit the battery and test the 12v and ground. If 12v is present with the ignition on, I wonder where it's getting it from!

 

[growlybear]

Highly unlikely a fuse pooped out. No doubt about it it's a serious issue when we are talking about airbags, you have no way of knowing if they will deploy in an accident.
I'm in the same predicament albeit from a different source. I'm waiting on a part now from the factory in Hiroshima Japan, eta is over a month. I'm hoping the young idiot who got into my computer didn't brick it.

My advice is to consult a professional, FIAT dealer or qualified private garage.

Thanks. Good luck with yours!

 

[spidermania]

Thank you and you as well, I feel the frustration and I know it's not what you probably wanted to hear. But it's the internet, and that means believe half of what you read and even less of what you hear. By the time you get done researching things you'll end up in a wild goose chase that never solves anything. But make no mistake, most dealerships and private garages are nothing but parts changers as well with very little diagnostic ability and if they can will gouge you to the nth degree. The only advantage is if they stand behind their work if something goes wrong.

 

[growlybear]

Thank you and you as well, I feel the frustration and I know it's not what you probably wanted to hear. But it's the internet, and that means believe half of what you read and even less of what you hear. By the time you get done researching things you'll end up in a wild goose chase that never solves anything. But make no mistake, most dealerships and private garages are nothing but parts changers as well with very little diagnostic ability and if they can will gouge you to the nth degree. The only advantage is if they stand behind their work if something goes wrong.

Agree, agree, agree but as they sing in Frozen I can't "let it go" !

 

[growlybear]

Here is the airbag system, with the wiring diagram showing F50 is the INT supply to the airbag ECU. On the location diagram, it shows the fusebox location of F50. In my "research" I can across a photo of the same fusebox with F50 fitted, but I can't retrace my steps to find it!

Does anyone have the same fusebox with F50 fitted?

 

[MSjoberg]

However, the airbag ecu must be fused somewhere?

It seems to be F50 for X290 also, according to the Electrical Circuits document in Downloads section

 

[growlybear]

It seems to be F50 for X290 also, according to the Electrical Circuits document in Downloads section

Thanks for this. It does indeed show F50 and state its use in the fuse table. It's very peculiar that the fuse table in the document (X250 euro 5) I attached does show the fuse location, but isn't in the fuse table. Maybe it was an oversite?

My Ducato vas a VIN starting X250, but on Mes, the body computer recognises the x290. I guess that's why it has the fusebox of the x290.

It's all so messy!!!

 

[MSjoberg]

Yes, for some reason Fiat kept 250 as identifier in the VIN also after the facelift to X290.

 

[HughJampton]

Again, a bit of conjecture here. The BCM controls the fusing of certain components by means of "soft" fuses. Certainly some of the lighting is protected in this manner (and the protection is presumably reset as and when any issue is removed).
Whilst there is apocryphal evidence that F50 protected (at least some of) the airbag circuitry at some time, that fuse isn't described in the later owner's manual.
I do wonder whether the function has migrated from standard fusing to "soft" BCM protection.

 

[the green vanper]

Taken from eLearn here's the description of the x250 euro5 airbag system. Could be helpful. I have no access to the x290 documentation

The control unit for the Air Bag system M060 receives an ignition-operated supply (INT) at pin 2 of connector A from the line protected by fuse F50 of the Body Computer M001 (pin 3 of connector G).

Pin 1 of connector B is connected to the Air Bag earth C050 (connector A).

Depending on the severity of the impact, the control unit activates:

• the driver's Air Bag Q009 which, via the clock spring on the steering wheel D047 (pins 9 and 10), is connected to the Air Bag control unit, respectively at pins 22 (+) and 21 (-) of connector A;
• the passenger Air Bag Q011, connected to pins 23 (+) and 24 (-) of connector A;
• the driver's side front seat belt pretensioners Q020, connected to pins 23 (+) and 24 (-) of connector B, passenger side Q021, connected to pins 22 (+) and 21 (-) of connector B and, if a two-seater front bench is fitted, the centre seat belt pretensioner Q019, connected to pins 14 (+) and 13 (-) of the same connector.

The Air Bag control unit M060 receives the signal coming from the driver's seat belt switch incorporated in the pretensioner Q020 at pin 10 of connector B. Connector B provides an earth reference for the switch from pin 5.

The control unit M060 is connected, via the CAN line (pins 7 and 8 of connector A), to the Body Computer M001 and to the instrument panel E050 for the management of the "passenger Air Bag disabled", "Air Bag failure" and "Seat belt not fastened" warning lights and the buzzer.

The "Mode", +" and " -" controls (pins 5 and 6) located in the left control panel H091 send analogue signals to the instrument panel E050 (pins 13 and 16). Pin 2 of H091 receives the reference earth from pin 36 of connector H of the Body Computer M001. This allows the deactivation of the passenger Air Bag, via the special set up menu in the display, causing the warning light to come on.


Reading from the beginning, it is likely that the error you managed to 'clear' was left after the airbag module has been replaced. If it has. Does the module looks new?

As it is hard to find any documentation regarding the x290, I'd disconnect the battery following the procedure from the owners' manual (which prevents damaging the airbag module!), then try to discharge any residual voltage from the system and yourself and then disconect the module, which will allow you to check if there's continuity between the plug and the F50 fuse.

That shall give you an answer if the airbag module is protected by the F50 fuse.

You could also check other fuses at the same time to be sure if there isn't another one that powers the module.

I'd also check the module's earth.

PINs / plugs are described above.

 

[MSjoberg]

Again, a bit of conjecture here. The BCM controls the fusing of certain components by means of "soft" fuses. Certainly some of the lighting is protected in this manner (and the protection is presumably reset as and when any issue is removed).
Whilst there is apocryphal evidence that F50 protected (at least some of) the airbag circuitry at some time, that fuse isn't described in the later owner's manual.
I do wonder whether the function has migrated from standard fusing to "soft" BCM protection.

There are a number of fuses that do exist but are not described in the user msnual. My interpretation is that Fiat wants the owner to visit a Fiat workshop when any of these fuses are broken.

 

[rayc]

There are a number of fuses that do exist but are not described in the user msnual. My interpretation is that Fiat wants the owner to visit a Fiat workshop when any of these fuses are broken.

The latest Ducato handbook has no fuse information just a dire warning under the ' What to do in an Emergency' section that fuses must be replaced by either a Fiat or authorised workshop.

 

[growlybear]

Again, a bit of conjecture here. The BCM controls the fusing of certain components by means of "soft" fuses. Certainly some of the lighting is protected in this manner (and the protection is presumably reset as and when any issue is removed).
Whilst there is apocryphal evidence that F50 protected (at least some of) the airbag circuitry at some time, that fuse isn't described in the later owner's manual.
I do wonder whether the function has migrated from standard fusing to "soft" BCM protection.

I was starting to agree with you, until I read a post a little further on, suggesting that they may not be documented as a dealer should change these. When I was pulling and checking fuses, the ABS light came on, and this caused the engine management light to come on, this necessitating the code clearing. I'll bet this is the same for the Airbag ECU fuse F50.

 

[growlybear]

Taken from eLearn here's the description of the x250 euro5 airbag system. Could be helpful. I have no access to the x290 documentation

The control unit for the Air Bag system M060 receives an ignition-operated supply (INT) at pin 2 of connector A from the line protected by fuse F50 of the Body Computer M001 (pin 3 of connector G).

Pin 1 of connector B is connected to the Air Bag earth C050 (connector A).

Depending on the severity of the impact, the control unit activates:

• the driver's Air Bag Q009 which, via the clock spring on the steering wheel D047 (pins 9 and 10), is connected to the Air Bag control unit, respectively at pins 22 (+) and 21 (-) of connector A;
• the passenger Air Bag Q011, connected to pins 23 (+) and 24 (-) of connector A;
• the driver's side front seat belt pretensioners Q020, connected to pins 23 (+) and 24 (-) of connector B, passenger side Q021, connected to pins 22 (+) and 21 (-) of connector B and, if a two-seater front bench is fitted, the centre seat belt pretensioner Q019, connected to pins 14 (+) and 13 (-) of the same connector.

The Air Bag control unit M060 receives the signal coming from the driver's seat belt switch incorporated in the pretensioner Q020 at pin 10 of connector B. Connector B provides an earth reference for the switch from pin 5.

The control unit M060 is connected, via the CAN line (pins 7 and 8 of connector A), to the Body Computer M001 and to the instrument panel E050 for the management of the "passenger Air Bag disabled", "Air Bag failure" and "Seat belt not fastened" warning lights and the buzzer.

The "Mode", +" and " -" controls (pins 5 and 6) located in the left control panel H091 send analogue signals to the instrument panel E050 (pins 13 and 16). Pin 2 of H091 receives the reference earth from pin 36 of connector H of the Body Computer M001. This allows the deactivation of the passenger Air Bag, via the special set up menu in the display, causing the warning light to come on.


Reading from the beginning, it is likely that the error you managed to 'clear' was left after the airbag module has been replaced. If it has. Does the module looks new?

As it is hard to find any documentation regarding the x290, I'd disconnect the battery following the procedure from the owners' manual (which prevents damaging the airbag module!), then try to discharge any residual voltage from the system and yourself and then disconect the module, which will allow you to check if there's continuity between the plug and the F50 fuse.

That shall give you an answer if the airbag module is protected by the F50 fuse.

You could also check other fuses at the same time to be sure if there isn't another one that powers the module.

I'd also check the module's earth.

PINs / plugs are described above.

Thanks for taking the time to post this document, although I attached the whole document as an attachment earlier in the thread. The ECU is dated 2023, so it was replaced and not reset. I didn't manage to clear any codes as the body computer won't talk to the Airbag ECU. I did the proxi align which then basically thought there was not an airbag system fitted at all!

Agree with your "I'd disconnect the battery following the procedure from the owners' manual (which prevents damaging the airbag module!), then try to discharge any residual voltage from the system and yourself and then disconnect the module, which will allow you to check if there's continuity between the plug and the F50 fuse." comment.

I've already made an additional earth which didn't help with this error.

Mondays job!!

 

[growlybear]

The latest Ducato handbook has no fuse information just a dire warning under the ' What to do in an Emergency' section that fuses must be replaced by either a Fiat or authorised workshop.

This does seem a little ridiculous don't you think?

 

[rayc]

This does seem a little ridiculous don't you think?

Especially as there are no Fiat Professional garages in my home county of Dorset to take it to. Even my nearest one in Southampton is booked up weeks in advance

 

[growlybear]

Especially as there are no Fiat Professional garages in my home county of Dorset to take it to. Even my nearest one in Southampton is booked up weeks in advance

I'm glad I bought Mes, as that would have been a trip to the dealer (I've not yet looked where my nearest Fiat Professional is). When I go away, I started taking my laptop and OBD2 leads with me!!

Just checked - got a FP just down the road (Chesterfield)