Technical replacing airbag control unit

[Zardo]

Hi,

since I had a short on my alternator (some kind of rust or whatever, located in the inner side of the casing did shove off the insulation of the coils, or the coils did get somewhat "bigger", so the short caused a high voltage peak once per revolution, and the battery light and red airbag light came permanently on (the wiper motor got cooked, too) and after the alternator was replaced, the motor ran a bit strangely for a time, sometimes stalling while idling, sometimes with "holes" while taking gas, but this is much better now, nearly normal.

As the airbag control light did annoy me, I took the car to FIAT to get the airbag control unit measured. I was told that no control codes of the airbag control unit did show up on the computer (which was connected to the diagnostic socket of the ECU), the control unit did actually not send ANY codes. They did then measure the voltage supply at the contról unit itself which turned out to be fine.

So they proposed to change the entire cabling of the control unit and the control unit itself, too. However, as control units of that kind are REALLY expensive (and it was not clear if it was still avaiblable) they proposed to find a scraped car without accident in order to get its used control unit out.

So that's what I'm trying now...

Is there anything to be careful about taking it out - or while replacing mine? Should I somehow "ground" the wire to the airbags? Or can the "ignition cable" be plugged in and out without probs? I would hate it to see my airbags explode while doing this ...

Thanks,
Zardo

 

[bridges]

The airbag ECU needs to be powered down. On a scrap car this should be the case as batteries are removed/disconnected. Just ensure that it has been.
Basically you disconnect the battery and leave it around an hour i'd give it a minimum of that. This is to allow any stored/remaining charge to drain from the airbag ECU. it can then be removed. This procedure will need to be done on removing and refitting it on your car also.

The airbag ECU's are very sensitive regarding voltage so you can't test them yourself with a voltmeter etc, particularly the wiring. So its just a case of unplugging the ECU and refitting the bought one.

 

[Zardo]

Thank you,

I tried looking for the airbag ECU today but I coudn't find it. I took the box of the glove compartment out and I found its control socket, instead. I tried following the yellow cables, one goes to the passenger side airbag, another crosses sides to the driver side, another one goes to the floor between the two foot spaces so I took of the little plastic covering of the foot space of the passenger side ... there was a metal case alright, however, I do not know if that's the ECU or if it is some kind of decelaration sensor.

EDIT: ok I found some description of it, the whole metal case is indeed the ECU. I wonder if it would be easier to dismount if I'd go for it from the left or the right side?

 

[Zardo]

Hi there,

all right I found the airbag control unit, took some pictures of it, too.

However, I have some trouble finding a identical replacement part on the scrap yards. "46413633" would be the number needed. On later models as about 1996, the numbers have changed. So I suppose a part with a slightly different number from another Bravo (like 1998) would not fit.

Any suggestions?

Thanks,
Zardo

 

[storm_rider_]

Watch the airbag ecu you get to. On the early cars i was told they weren't earthed so you can spike them like you did easily. The wiring is slightly different to. The later cars have earth straps on them and shouldn't be able to be spiked the same way. I know a good second hand one here is about $400-450 NZ dollars, and a new one was over $900. There is a company in england that rebuilds them to but doesnt give any guarentees. I think they were a bit more than a good second hand one. I ended up building a timer instead for $20 and jerry rigging it. Light goes on and out like the ecu was there, lol. The airbag in mine is still there but disconnected from the steering wheel so it can't discharge. Not a particularly legal way but definitely cheaper. . I intend to pull the steering wheel to so i dont car to much about the fact the car doesnt have an airbag in it.