Airbag fault (D9 semi-mux)

[Doggy]

Hope someone can help with this - my bro's X-reg 110 exec estate, (RPO 8751) has a flashing airbag w/l and the fault message:
Permanent fault - Passenger trigger open circuit, which I take to mean the passenger seat belt pre-tensioner is failing the self test.
Problem is, I can't identify the relevant connector under the seat - his car seems to have no less that FOUR 2-pole connectors to choose from.

Does anyone have access to a circuit diagram, or any other info that would help narrow it down?

The fault won't clear, I've tried repeatedly unplugging/replugging every possible connector without affecting its behaviour. it might be I need to attack the multiplug at the ecu, but I would rather positively rule out the plugs under the seat before ripping the centre console out.

[GingerMagic]

Hi Eric, there is another connector slightly behind and above all the others - its very small and discrete, maybe behind the metal front crossmember thingy - if there is an orange wire in it then try this one.

I also get a similar fault when I have deactivated the passenger airbag with the key switch between the seats.

[markw]

Assuming your brother's Estate is wired the same as my Coupe, the small rectangular Blue connector is for the side air bags in the seat and the Brown connector of similar dimensions is for the seat belt pre tensioner. Both these connectors from the seat side, have thin, 2 core orange cable going to them.
If you see a Red connector with just one wire in it, that's the earth for the side air bag unit and can also trigger a fault light during self test.

The fault message you're getting could also refer to the Passenger Air Bag (in the dash), couldn't it?.....nothing to do with under seat connectors.

[steve_earwig]

Or it could refer to the driver's side, if it's mis-wired (like some of them were...)

I've been staring at Sedra for an hour now, it looks like all the connectors are orange, apart from the blue one which is red I think I need to take a lie down

I also suspect that Sedre is wired up wrong, rhs & lhs side are all screwed up on right-hookers

[Doggy]

Thanks for your comments and suggestions everyone. I tried to familiarise myself with the full-mux diagrams on Petrila, before looking at it, but it didn't help much. Their diagrams definitely have the driver/passenger left/right distinctions to match LHD cars, but it never occured to me it could be just as mixed up in what it reports via pp2k.

Mark, it could be the airbag in the dash, (or even the steering wheel, taking Steve's point), but I thought the former to be less likely than the ones under the seat as it's out the way of damp carpets and doesn't get moved like the seats, but you never know. This one sounds a bit like your coupe, but the connector colours are different. I think it had brown, yellow and green 2-pole connectors, plus a red one with only a single green/yellow wire, (but I can't be sure I've remembered all of it correctly).

Guess I should disconnect the pre-tensioner on the drivers side and see if that gets me a different error message, or mybe even fixes it when you plug it back in.....

This isn't the first time I've looked at it, had a go just after he bought the car and I think I disconnected/reconnected every plug under both seats before plugging the laptop in to see what it said. Trouble is it's almost MOT time now, I'll get one more look at it next weekend then he'll have to take his chances.

Even odder, on pp2k I looked in the section for airbags/seatbelts and it gave me 3 options, IIRC:
Seat belts/airbags
Left side protection
Right side protection

- implying there are 3 separate ecu's. (It has airbag symbols on the window side of each seat backrest, like my 52 and 03 reg cars have had).
When I interogated the first ecu, it reported the error above and wouldn't clear.
When I tried the second one, it reported a side airbag fault, that did clear.
The third one gave me the 'ECU has not replied' message despite various attempts.

Anybody know if it really has separate ecu's? Later cars have one ecu with a 50-way connector, with something like half the pins used.

[markw]

Sorry to keep on comparing with the Coupe but there are 3 separate ecu's.(on mine, which is 2001 part mux anyway)
One under centre console near handbrake. This is to trigger driver's and passenger's front air bags and seat belt pre tensioners.(ie frontal impact)
Two (one on each sill, to capture side impacts)) for the side airbags in the seats. These ones are really hidden. The seat has to come out and the carpet lifted to even get a glimpse of them......

[steve_earwig]

Yeah, I noticed the 3 ecus earlier, on the full-mux diagrams the other two appear to be down below the seatbelt reel on the sill somewhere both sides. Out of curiosity I looked on Service Box and I'm sure there was an RPO mentioned, presumably for when they went to the later (central) ecu.

Maybe if you unplug one you'll know which side you're looking at

[GingerMagic]

On the fully mux you can switch off the faulty airbag with pp2000, just to get through the mot. Not sure if its possible with a semi mux.

[steve_earwig]

I forgot you wanted a wiring diagram, sorry Here it is, FWIW. It's a lousy semi-mux microfische, I tried cleaning it up but it only got worse



I'll add the wire codes later, I've made a start but they disagree with the list I already have, so I'll have to do the whole lot manual-like

[Doggy]

That's absolutely brilliant Steve, thanks.

I can read all of it at 150% zoom, so no need to add the codes, (unless you reckon they're wrong). If it's easier a comparison list might be just as good.

[steve_earwig]

I meant, what the codes mean:
CT00 : steering wheel rotary connector
6565 : driver airbag module
6564 : passenger airbag module
6576 : pretensioning seat belt (passenger side)
6575 : pretensioning seat belt (driver's side)
6562 : lower front RH side airbag module
6571 : side air bag unit (right)
6572 : side air bag unit (left)
6563 : lower front LH side airbag module

I dunno about wrong, it's just when it starts bringing up knee airbags and rollover hoops I start loosing the will to live

[Doggy]

That's great, thanks again.

I guess 6571/2 are the other ecu's. I didn't realise there were 3 - maybe one is dead, or if I'm really lucky, the plug's fallen out.

[steve_earwig]

Stranger things have happened...

[gumby6371]

On the fully mux you can switch off the faulty airbag with pp2000, just to get through the mot. Not sure if its possible with a semi mux.

I didn't know that, any clues on how it's done just in case I don't get mine sorted in time???

[GingerMagic]

Test by ecu - airbag ecu - fault read to find which one is causing the error - back to ' configure ' and label that airbag as absent. Test it by fault reading again.
This isn't a fix but it can buy you some time.