Technical Body Control Module BCM questions

[Genesius]

I all. I’m new to Fiat so bear with me.

I’ve bought a Punto Sporting 2011.
It’s got some BCM issues relating to airbags and stop start.
The previous owner said it needed the BCM sorting.

I’m looking and there’s so much info I can’t seem to find what I need.

What exactly do I need to do? Previous owner said if I find a BCM with the same numbers it’s a straight swap. Is this true? What numbers, because there are a few on the sticker.

Thank you for your help

 

[Pugglt Auld Jock]

Very much doubt if it would be a straight swap. Some sort of "virginisation" of a second hand unit would probably be needed? and then it would need to be electronically introduced to the vehicle systems? However let's take a wee step back before we go spending lots of dosh. There are two very common problems on small Fiats which need checked out first as they can cause all manner of problems.

This is going to sound stupidly simple but get your battery properly checked out. It needs to be in tip top condition, these vehicles don't like "iffy" batteries and just because it starts the engine doesn't mean it's good enough to satisfy the electronics! Also take a detailed look at the engine earth cable which can corrode badly. Both these things can cause stop/start to drop out and other "strange" things to happen.

If the battery is good then you need to identify exactly what the car thinks is wrong with it so you need to get a read out of stored trouble codes and you'll need a code reader or scanner for that. If you plan on working on Italian cars much then I can strongly recommend Multiecuscan: https://www.gendan.co.uk/multiecusc...8DtJ8kna_zbH6Y3SZU2hYMJ3qT7u9sdkaAkcKEALw_wcB I've intentionally linked you with Gendan who are well worth a call to discuss what might be best for you. I've bought stuff from them, including Multecuscan and find their backup second to none.

Hopefully once you've scanned the modules for codes you'll be much better informed about what the way forward might be - which may, or may not, include installing a new Body Control Module.

I have a flashing mileage indicator on my boy's 2012 Punto at this time - a not uncommon symptom I believe. I haven't yet had a chance to scan it for codes but I suspect a communication problem involving the BCM and I may be able to sort it by running a Proxi Alignment using Multiecuscan. This will be very exciting for me as I've never done a proxi alignment before! Here's a video which shows it being done on a 500, I believe it's exactly the same procedure on his Punto:

 

[varesecrazy]

Hi

The earth cable is a common failure.. cheap and easy to change

Historically damp.in the fusebox too ..the lid was awkward to refit.. lots of cases of water ingress

What age is this 199..??

This link should still be relevant:


Charlie .. punto owner

 

[varesecrazy]

Link here:

The Electrical gremlin thread....... | FIAT Grande Punto

So you have had one or combination below: Imobiliser light staying on Random power steering issues Battery charging issues Lights looking dimmer than normal Airbag light coming on Car been weak starting dispite battery been healthy Random temperature gauge readings These all can be a...

www.fiatforum.com

 

[Pugglt Auld Jock]

Here's another very interesting video regarding the problem I am experiencing with my boy's car, but of interest to you (the OP) because it would seem to say you don't need to "virginise" a used unit, you can just pop it in and do a proxy alignment? Anyway, here's the video:

I like this guy's stuff and have subscribed to his channel and will be working my way through his videos. One thing I'd like to know more about is that, I believe, a proxy alignment can go wrong in a big way if the info it's writing to the modules becomes corrupted. I believe it's advised to save the existing info before attempting the procedure? but I don't know how to do that yet and I don't know how you would perform a recovery if it all went to hell. Anyone reading this who can advise I'd be very interested to know more.

 

[koalar]

I all. I’m new to Fiat so bear with me.

I’ve bought a Punto Sporting 2011.
It’s got some BCM issues relating to airbags and stop start.

Airbags have very little to do with the BCM it has its own computer module, the BCM only puts on the light

The previous owner said it needed the BCM sorting.

I’m looking and there’s so much info I can’t seem to find what I need.

What exactly do I need to do? Previous owner said if I find a BCM with the same numbers it’s a straight swap. Is this true? What numbers, because there are a few on the sticker.

He lied. The body computer is the immobiliser it need the remote, vin, keys programmed into it

Otherwise you will also need the complete lock set and ECU as well from an identical car

Thank you for your help

Read the code would the first step

 

[varesecrazy]

Indeed.. use a proper system for an accurate FIAT code

MultiECUScan is what you want access to.. see the forums user list


Here are a few other pointers.. cheap items

Punto Evo bcm cost | FIAT Punto Evo

Thank you 🙂🙂

www.fiatforum.com

 

[koalar]

Fingers crossed it turns out to just be the passenger airbag switch

Very common

 

[varesecrazy]

We seem to have all 3 uk nations covered for Italian diagnostics..

Wonder where the OP is based..??

 

[Genesius]

Hi all, thank you so much for taking the time to reply.

It’s a 2011 model and I’m in Essex.

I’m not entirely sure the BCM is at fault after reading your replies, I was just going off of what the previous owner said. He has gone to the trouble of removing the BCM shield and said he has had a few of these before so took his word for it.

The multi ecu scan you have linked; what can that do that my Autel/icarsoft can’t? Does Fiat need a specific code reader?

 

[varesecrazy]

MES software will give accurate P C and U codes

Often generic stuff gives VW .. or Honda.. codes it can be misleading

I find Searching the Code you get on here will give a great result

 

[Genesius]

Bcm shows this lot

Ecu shows this

And instrument panel shows:

I can’t even see the SRS module so I can’t read that.

Voltage was sitting at 12.07v

Wiper code should be ignored because it’s been removed.

 

[varesecrazy]

Worth checkng tailgate wiring

 

[Genesius]

Worth checkng tailgate wiring

a visual check?

 

[varesecrazy]

Yes.. visual


search
'Maybelline' on here for a good idea of what chaos can ensue..

The 500 is the worst for cable failures.. but 199 puntos can have similar

 

[koalar]

Dam

No communication between the BSI to the airbag control unit

Not a simple fix

If you do a proxi alignment it will not see the airbag and disable it and the light I believe. Never tried it myself

There no easy way to test the module and wiring

It’s likely to be the airbag unit if the car hadn’t been touched

Could be
Wiring
BSI
Airbag module

I don’t like guessing, always worth reseating electrical connectors first

 

[AndyRKett]

What exactly do I need to do? Previous owner said if I find a BCM with the same numbers it’s a straight swap. Is this true? What numbers, because there are a few on the sticker.

No because in Fiat's the engine ECU and the Body control module are what operate your immobilizer, they pair when the car is new and are coded to the cars keys so if you replace on you need to replace the other and keys as well. Or you need to buy a "virgin" unit which once installed will code itself to the engine ECU and keys on first use.

 

[AndyRKett]

Fingers crossed it turns out to just be the passenger airbag switch

Very common

there wasn't one on every Punto since the Grande, the mk2b was the last car to have a physical switch. The later cars activated and deactivated the passenger airbag with a setting in the instrument cluster.

 

[koalar]

there wasn't one on every Punto since the Grande, the mk2b was the last car to have a physical switch. The later cars activated and deactivated the passenger airbag with a setting in the instrument cluster.

Cheers but doesn’t matter now

The original poster has since posted error codes

It a serious problem

There no communication to the airbag module at all

 

[koalar]

Or you need to buy a "virgin" unit which once installed will code itself to the engine ECU and keys on first use.

I don’t believe a virgin BSI will work

Clone involves swapping the eeprom and flash it’s crypto protected no two units are the same

A blank ECU will read from a working BSI. Been done many times

I have never seen anyone successfully fit a secondhand BSI bought of eBay or similar.