Air bag ECU ~Incorrect? Replacing, re-wire, what shall I do?

[Sonia406]

Late last year on start up she had the air bag light flash up, I wiggled some wiring under the passenger seat. Re-started her and they had disappeared.
I had a friend come and do diagnostics on it only the last week, PP2000 say it is an 'incorrect ECU' for the airbag.

I put it to you, Is this a case of lose wiring or has it really been fitted with an incorrect ECU? In which case, is it a job where I have to take the passenger seat out to do? I am yet to read my Haynes but thought I would ask here in any instance...... Thanks

[lozz]

Hi iirc, the airbag ecu lives under the centre console,

incorect ecu, idoubt it, itl be more than likely bad connections,
unplug everything and plug back in 1 at a time and see what happens,

Morethan likely it will be a bad connection,on the seat belt restraint /anchor one,
( Bright orange cableiirc )
No need to remove the seat,


(!Please dont have the ign on whilst working on any of the above, just a word of CAUTION)
(BE CAREFUL!)

[Sonia406]

Hi iirc, the airbag ecu lives under the centre console,

incorect ecu, idoubt it, itl be more than likely bad connections,
unplug everything 1 at a time and see what happens,

Morethan likely it will be a bad connection,on the seat belt restraint /anchor one,

No need to remove the seat,

Oh, so the air bag ECU is not under the passenger seat? I haven't properly investigated just knew to ''twiddle'' (technical term that) the cables under it and sure enough it went off... Thanks for your help... if I find a lose wire, how easy will it be to re-wire? Thanks again

[lozz]

Rewire?

you Wouidnt /shouidnt have to, normaly ?
just look at the connectors, the one on the orange cable has two prongs, just bend them in slightly,
the plug will lock in tightly then, ifind the one that is on the orange cable is normaly the culprit,

[Sonia406]

Rewire?

you Wouidnt /shouidnt have to, normaly ?
just look at the connectors, the one on the orange cable has two prongs, just bend them in slightly,
the plug will lock in tightly then, ifind the one that is on the orange cable is normaly the culprit,

Thank you Most appreciated... Will let you know how I get on tomorrow

[lozz]

good luck

look under the seat and look at the one that goes to the seatbelt set up,
you will see connector on it ,if you feel it there will be loads of movement in it (loose)
if so unplug it and you will see 2 metal parts get something thin and pointy and bend them inwards not alot just slightly.

[Sonia406]

good luck

look under the seat and look at the one that goes to the seatbelt set up,
you will see connector on it ,if you feel it there will be loads of movement in it (loose)
if so unplug it and you will see 2 metal parts get something thin and pointy and bend them inwards not alot just slightly.

Also worth knowing... May be under the seat as that was what I played with last time, if I do both ends and it still plays up is that likely to be a break in the wire?

[lozz]

Hard to say if it will be a broken wire,
normaly its not and can down to a bad connection at the plugs /connector's

if a car has or has had more than one driver this couid be an after affect,

Seat getting moved forward/backwards over time cause's these Gremlins,

[Sonia406]

Hard to say if it will be a broken wire,
normaly its not and can down to a bad connection at the plugs /connector's

if a car has or has had more than one driver this couid be an after affect,

Seat getting moved forward/backwards over time cause's these Gremlins,

I stand no chance then lol. In it's first few years it was a hire car... since 2005... One owner then until Dec 2011 when I got it........ Darn it

[lozz]

Ah rite, thats probably whats caused it then,

Still you will be able to sort it, its not big problem, ithink most 406 owner's have had this,

[Sonia406]

Ah rite, thats probably whats caused it then,

Still you will be able to sort it, its not big problem, ithink most 406 owner's have had this,

A really common fault then, Thanks for having faith in me!

[Doggy]

Had this on my previous 406 - happened virtually every time the passenger seat was moved. As lozz says unplugging / replugging the 2-pole connectors was a temporary fix. These are the connectors for the seat belt pre-tensioners, (which they like to call pyrotechnic devices, sounds better than E X P L O S I V E S, they think). Due to the nature of this circuitry, the ecu applies a miniscule signal to check continuity on initialisation and the tiniest trace of oxide film on the connector pins will prevent this circuit test from working.

Finally I chopped of the connectors, fixed screw terminal connector blocks onto the original connector mounting brackets, so you could still disconnect if necessary - I prefer this approach to the more common practice of twisting the wires together and soldering them.

[Sonia406]

Had this on my previous 406 - happened virtually every time the passenger seat was moved. As lozz says unplugging / replugging the 2-pole connectors was a temporary fix. These are the connectors for the seat belt pre-tensioners, (which they like to call pyrotechnic devices, sounds better than E X P L O S I V E S, they think). Due to the nature of this circuitry, the ecu applies a miniscule signal to check continuity on initialisation and the tiniest trace of oxide film on the connector pins will prevent this circuit test from working.

Finally I chopped of the connectors, fixed screw terminal connector blocks onto the original connector mounting brackets, so you could still disconnect if necessary - I prefer this approach to the more common practice of twisting the wires together and soldering them.

I do wonder if the passenger air bag would be a 'fail' if I turned it off and if the fault then disappeared?
Sounds like one needs to invest in a soldering gun lol - thanks for all this advice, I keep reading and the more I read the more I realize Lozz was right and it's a really common fault.........

[hammerman]

its not big problem, ithink most 406 owner's have had this,

My late 2003 does this.About once a year the air bag light will come on.It did it for the first time in a tear 2 weeks ago.I just wiggled the connection under the passenger seat & its been "fixed"ever since.My previous xantia did the same & i replaced both the connections under both seats & never had a problem again.

[Sonia406]

its not big problem, ithink most 406 owner's have had this,

My late 2003 does this.About once a year the air bag light will come on.It did it for the first time in a tear 2 weeks ago.I just wiggled the connection under the passenger seat & its been "fixed"ever since.My previous xantia did the same & i replaced both the connections under both seats & never had a problem again.

Problem is, If I do just wiggle it and it goes off - IF it comes back on during or just before the MOT that's an instant fail and I don't want to risk that....
I did wiggle it before and it's already come back (though the seat has NOT moved after the wiggle) so ..... Needs more attention... feels like I am about to try and defuse a friggin' bomb lol