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ASTOBBS · #1 18-08-10, 23:22

Just got a few questions regarding airbags in vectra B's.

Firstly, I have swapped my steering wheel from a 3 spoke to a 4 spoke due to the 3 spoke being really shabby, would this require re-coding of the driver airbag?

Second, what is re-coding, when is it required?

Thirdly, my car is a prefacelift, and a previous owner replaced the stash tray above the glovebox with the airbag cover as found on facelift cars equipped with passenger airbags. The job wasn't that brill and I had to make it neater when I got the car, whilst at the scrap yard again today, I decided to get a new cover, and so found there is infact an extra bracket required, so I got the whole lot while the going was good, cover, bracket, airbag and bolts / screws. Wasn't expensive so I was happy with the haul.

On getting home and still having the dash half in bits, its the obvious time to think about fitting the airbag, but I found the plug to be different, it is present in my loom - denoted by the yellow sheathing, but the plugs don't match. So I left the airbag out and just fitted the frame and cover.

Can I chop the wires in, wires are wires afterall regardless of the plug, are they polarity sensitive? Also why would the plug be different, are there two (or more) generations of passenger air bag? What kind of signal is sent to the airbag when its fired?

Would this require re-coding?

Also I have an extra fault code now, driver squib high resistance, its the same squib but may have got damaged when removing the 3 spoke wheel.

Thanks

matt-m · #2 18-08-10, 23:27

drivers air bag is fine just make sure the battery is disconnected if not the airbag light will come on and stay on reprogamming is called tech 2 which you have probaly heard which is used to find fault codes and re-set the airbag light .....the passenger one im not 100% as i carnt rember if the pre face was avalible with a passenger air bag the seats i put in my pre face have air bags in but i didnt connnect them the dash mod you have done looks better than the hole or cubby but lee maybe able to give you a better idea

ASTOBBS · #3 18-08-10, 23:45

Thanks, I have OPcom, have kind of answered my own questio here by reading this

http://www.vezerdiagnosztika.hu/OP-C...bag_Coding.pdf

That rasises the question, should I have got the SRS unit from the donor car too, which would be pre-configured with the two airbags and the two pretensioners, but would that in turn need to be matched to my ECU?

matt-m · #4 19-08-10, 00:00

one ansewer to that LEEKYYYYYYYYYYYYY where are you

Leeky · #5 19-08-10, 00:18

I'm here.

You need the Airbag SRS ecu from the donor car Andy. Its located underneath the coin tray. Its possible the Vectra uses different airbags on earlier models. I have an airbag somewhere, take a pic of your plug and if it fits the one I have you can have it.

I don't really know enough about SRS internal cicruits to suggest replacing the plug. Personally, as a qualified mechanic I've always left these circuits alone - Too much rides on there safe operation, and they're closed systems so care must be taken in anything you do with them.

All airbags and pre-tensioners should be treated with the care and respect they deserve; they're essentially explosive devices.

I'll have a look on EPC and report back regarding the airbag issue.

Leeky · #6 19-08-10, 00:31

As I thought, there are 3 types:

Sorry for the size, but its much easier to see at full size.

ASTOBBS · #7 19-08-10, 08:30

figures, my plug is a roud pin type for starters where as the airbag I've got has flat pins.

I did a bit of reading last night, seems the detonation begins with a heating element, which recieves 2-3amps and starts an inital burn which then gets the main burn going and evolves the gas (nitrogen in most cases).

If its just a heating element then its not polarity sensitive surely.

Do you know if the srs unit is matched to the ecu aswell?

Thanks

Leeky · #8 19-08-10, 10:44

I couldn't comment. I've seen the explosive devastation they cause first hand though.

The SRS ECU it seperate to the Engine ECU. You can just change it and as long as its programmed state matches your current state (e.g. you have the same airbags) all should be OK. If anything it will throw up codes initially that you can just wipe with the opcom.

A word of warning: When you reconnect the battery, do it with the keys in the ignition (turned on to show ignition lights) and with the door open. Do not be sat in the car when you first do it incase something goes wrong and they fire.

The same goes for when you clear the codes. Never do it sat in the car (ever) if your toying with the airbag ECU's. If it goes off in your face it will likely kill you.

ASTOBBS · #9 19-08-10, 11:22

Thanks Leeky, unfortuantely I havn't done the bit with having the key on position 2 when re-connecting the battery.

I've had the airbag light on for months now anyway, today while fiddling with the opcom, I see in the measuring blocks two boxes

Airbag Configuration - ECU NOT PROGRAMMED

Pretensioner Configuration - ECU NOT PROGRAMMED

Is it possible my srs unit is duff? Surely there should be something there.
any attempt at programming fails. The airbag light came on on a cold morning when the battery only just managed to start the car.

Its been on since, with codes 44 and 37, tell tale signal open circuit (the bulb is on how can it be open circuit) and pass. pretensioner high resistance, yet in the measuring blocks the resistance is the same as the driver side.

Seems a bit weird.

Oh and when referring to taking the battery off to let the capacitor discharge, where is this capacitor? In the airbag or the srs unit, is this procedure needed to make the airbag safer, or simply so that the light doesn't come on?

Thanks

Leeky · #10 19-08-10, 11:38

In regards to airbag discharging problems; people are advised to let the circuits drain before trying to touch airbag components. As I understand it, the power storage is held in the ECU itself. I don't really see how applicable it is with modern systems in all honesty.

As bad as it sounds I regularly used to replace steering com clusters on 206/307's, which involved removing the airbag, and the steering wheel. I never used to remove the battery lead first. I was younger then and in hindsight it was rather stupid. However, its only going to fire if you short the connections and/or cause a spike as you connect it up. This is the reason why you stop all power before touching them. I've seen an airbag deploy with a technician in the car before now, and it nearly killed him and wiped out one of our brand new diagnostic machines as well.

Regarding your codes, I'd change the airbag bulb. Regarding your pretensioner that sounds more like a loose connection under the seat, or it recieved too little voltage on that cold day. What happens when you clear the codes?