Technical Air Bag ECU 1995 mk1 type/make

[old dear]

Hi Folks my multiscan 2 will not connect to the air bag ECU (works fine on the engine ECU ) i have been told by the Multiscan forum folks that my early mk1 could have a different airbag ECU fitted to the TRW one ,could any member tell me what other make could be fitted ?

thanks

 

[nicholasb]

This is the airbag ECU in my early 1995 Mk1. There are 3 or 4 types of airbag sensor as far as I remember. This is an early one.

 

[old dear]

This is the airbag ECU in my early 1995 Mk1. There are 3 or 4 types of airbag sensor as far as I remember. This is an early one.

View attachment 415195

many thanks ,im pulling whats left of my 63 year old hair out with this barmy air bag lark ,ive built engines in less time lol

 

[Wiltshire Chris]

I did some digging but don't think I've found gold. As far as I can tell from ePer there were three different units:
46735061 ??? to 15/1/1996
46443798 TRW to 15/12/1998
46535343 TRW from 15/12/1998

I then had a look on the Barchetta lexicon site and that seems to confirm this and identify the maker of the early ECU as 'Becker' (googling Becker airbag ECU finds a few matches similar to @nicholasb picture above). Sadly it looks only the latest TRW ECU can be accessed but I spent most of my german lessons at school looking out of the window so you might want to double check all this.

barchetta-Lexikon : Projekt Zugriff auf Motor-, Airbag- und ABS-Steuergerät

Umfassendes Lexikon mit vielen nützlichen Informationen über die Fiat barchetta für Bastler und alle, die mehr über ihr Auto wissen wollen.

www-barchetta--lexikon-de.translate.goog

from that page:

Airbag​

• Steuergerät 46735061 Becker - keine Chance
• Steuergerät 46443798 TRW - keine Chance
• Steuergerät 46535343 TRW, KKL-Adapter an OBD-II, K-Leitung auf Pin 3 oder mit Adapter an 3poligen Adapter (je nach Baujahr) - geht definitiv
  

 

[old dear]

ok folks my car has got the Becker air bag control fitted ,can any member tell me what soft wear i need to re set it, ?

thanks

 

[Voko]

I don’t know anything about these early modules, but I wonder rather than software it could be something similar to the Becker system described in this thread? https://www.alfaowner.com/threads/airbag-ecu-reset-i-know-i-know.319642/

Good luck

Mike

 

[old dear]

Yes thanks i have tried the blink codes and it is not re setting ,so i thought if i can get a laff top plugged in it may re set with the correct program but i will have another read of the link thanks

 

[s130]

Yes thanks i have tried the blink codes and it is not re setting ,so i thought if i can get a laff top plugged in it may re set with the correct program but i will have another read of the link thanks

Not the excellent reference link states:

"Fault codes can be deleted (exception fault code 09) by connecting pin 3 to ground for 5 to 10 seconds. One fault at the time is deleted."

So if you originally had multiple faults then you will have to reset, reset, reset, n times till all clear.

 

[varesecrazy]

@s130 Thats very interesting

@old dear
if you CAN successfully clear those Blink codes by that method do let us know

 

[Wiltshire Chris]

Not the excellent reference link states:

"Fault codes can be deleted (exception fault code 09) by connecting pin 3 to ground for 5 to 10 seconds. One fault at the time is deleted."

So if you originally had multiple faults then you will have to reset, reset, reset, n times till all clear.

If @old dear is successful with his reset it might be worth someone (happy for it to be me) to extract the useful information from that into a Guide with links to the original. It might make it easier for a B owner in the future to find it. Obvious caveat to be included about it only being for the early, Becker, airbag ECU.

 

[old dear]

yes the blinks definatly work by connecting the blue and black wire for up to 5 seconds or re set up to 10,even if you plug the multiscan in ,it will come up with no connection ,put once you press Y the car will start blinking saying 12 volt supply picked up ,my blinks originally were 4 and 6 so i took the seats out and re did the pre tensioner wires and connectors because inside the seat runners the wires had broken insulation with the copper showing ,now i am on code 2 only saying faulty control unit .....but befor i pull it out i would like to try and re set it with a laff top program just to make sure i have no blinking ecu gremlins in there .....onwards and upwards lol

 

[Voko]

Apologies if you know this already, but I had a poke around there's quite a lot of detail on the airbag system in the service manual. In particular there's this part which gives the official fault finding guide on the Becker system. The service manual is available in the 'downloads' section of the fiatforum.

 

[Wiltshire Chris]

Apologies if you know this already, but I had a poke around there's quite a lot of detail on the airbag system in the service manual. In particular there's this part which gives the official fault finding guide on the Becker system. The service manual is available in the 'downloads' section of the fiatforum.

Good find. I should have remembered that was there as I ploughed through every page when I did the table of bookmarks. My ECU needs fault finding too it seems!

 

[old dear]

yes i have the tee shirt lol on the fiat manual and the codes ,im still digging around once i get sorted i will report back ,i cannot seem to win i have an XK8 with a fuel pump gone ,a 3 lite s type manual that needs a flywheel and 2 mgs that need welding .....plus the baby fiat air bag ,the only consulation is i never bought the 3.2 boxster lol

 

[old dear]

yes i have the tee shirt lol on the fiat manual and the codes ,im still digging around once i get sorted i will report back ,i cannot seem to win i have an XK8 with a fuel pump gone ,a 3 lite s type manual that needs a flywheel and 2 mgs that need welding .....plus the baby fiat air bag ,the only consulation is i never bought the 3.2 boxster lol

OK folks after much prattling about i have removed the control unit and my friend is an electronics boffin is going to have a look ,but basically the car was fine until the seat was moved,then the light lit up so i took the seats out ,re wired the pre tensioners because a seat rail pre tensioner wire had rubbed through ,ohmes tested the seats with new wires at 2.7 to 2.6 ohms ,fitted the seats back and soldered the seat connections ie hard connections not push fits ,then spent 3 days trying to get Multiecuscan working which it does not with the Becker air bag control unit ( multi works great on the engine ecu with the correct drivers and port settings on the laff top ),so then after hours of reaserch and a lot of assistance (thanks to multi forum,vag,forum,this forum,and FB ) I went back to plan B on the re set after not been able to find an electronic idiot proof program i could use so into the blink codes ....car could not re set giving code 6 then another time code 4 ,then code 2 ,so im thinking the electronic bits in the box have gone nitts up because of the diffrent codes and no re set ,so the moral of the Story .....identify the air bag ECU First then see what re set tools there are ,multiscan does not work with the 95 becker But the car will sence multiscan when its pluged in and connected by the air bag light blinking ,so now im off to see my friend the Vintage amp doctor who has 50 years of electronic,s workshop experience to see if he can work his majic ,and if not i will need a good becker box .


also folks can i run the car with the air bag control removed and the air bag light on ? ,ie the air bag will not go off wile im driving ?

thanks folks for the help

 

[Wiltshire Chris]

car could not re set giving code 6 then another time code 4 ,then code 2 ,so im thinking the electronic bits in the box have gone nitts up because of the diffrent codes and no re set

As @s130 said above you do need to keep repeating the reset, is it now the case that you always get 2 blinks which means 'control unit fault'? Codes 6 and 4 look like they could have been the faults you fixed with the re-wiring and they're now cleared from the EEPROM. If the code 2 won't clear then that would seem to indicate a fault with the sensor now which maybe your friend can resolve? My only concern over a repair is that you very definitely don't want it firing by mistake in future. In theory it'd be quite simple to build an airbag sensor with a small Arduino and some components but I wouldn't want to be responsible for the logic that determines you've crashed rather than braked hard or hit a pothole

Henk does have a replacement Becker crash sensor in stock:

Airbag Crasch sensor 1 - Barchetta Parts

Airbag

barchettaparts.com

As to running without a control unit then I can't believe that anything else would cause the airbags to fire so I'd guess it would be fine (assuming you don't hit a wall and need the airbags!) but I am in no way an expert. Indeed, I read on one forum someone just replaced their ECU with a box that lit the warning light up for the couple of seconds on startup so the MOT could be passed, again, your gun your foot as my old boss used to say!

 

[old dear]

basically most of my time was wasted trying to connect the multi scan which is a no go , i have sat hour 2 hours or more trying to re set the blinks ,its not happening ,the first code that came up was passenger side crash censor,so i pulled the seats out and re did everything ,when re assembled ,all i was getting was 2 blinks ie control box fault.....and after keeping at the re sets and blinks i have gone from 2 to 4 to 6 ,i take your point bought getting the control repaired ,i might give that a miss ,drive the car without the control and wait for a control unit thats within my 75 quid budget ,still nothing lost ,i have learnt a bit,and certainly got to grips with multiscan it works great on the engine ecu .

 

[Wiltshire Chris]

Just a thought. A member of the UK owners' club is listed as having two Barchettas that he's broken for spares. It's the last entry on this page:

Buy & Sell

fiatbarchetta.uk

The entry is dated from February but it might be worth a shout?

 

[JMSG]

i remenber reading something about older airbag units in the forum and a software cabable of reseting them ... it's a question of diging in the old airbag post ...
i found this , give it a look .

Airbag lamp clear/reset on pre-obd B circa 1995 | FIAT Barchetta

To reset the airbag light on a pre-obd (circa 1995) Barchetta using Blink codes. This is my attempt to simplify and clarify the process of carrying out this task. :D Can be used if you have inadvertently removed the seats without disconnecting the battery first :D This guide is based on the...

www.fiatforum.com

 

[old dear]

there is a company in Granada that inspects /re sets them ,i have done the manual blink codes to death ,so im going to post it to the Granada folks ,see if they can test it/re set it ,t as o me its crazey paying 200/300 euros for 25 year old plus electronic units ,but if i really get stuck i will look for another unit at a sensible price ,thanks for all the help /advice ,i will post the results of my air bag endeavors once i have had the unit inspected (i opened the unit up and its bone dry so at least it hasn't been in any water ) onwards & upwards lol