C 1 AIR BAG FAULT

[JOE+TECH]

Hi checking out air bag fault on 2010 citroen c1
Air bag light was on in instrument fault logged for for coil spring on column
Replaced coil spring, cleared fault = now no faults present
Problem is air bag light is still present on instrument, tried refitting faulty coil spring fault returned
Refitted new coil spring faults cleared again , no faults
Has anybody seen this fault ?
I would like if possible wiring diagram for airbag system and instrumemt cluster
Vin No VF7**************[VIN obfuscated, can be read by forum staff]
As I think If airbag module sees no faults, It would send message to instrument to turn off air bag light is this correct ?
There is no facility for checking out instrument cluster.I am using Diag tool so would like to check the wiring connections between air bag and instrument
Thanks Joe

[PaulC5]

I am probably wrong, but I think if an air bag light comes on it needs a code reader that does air bags to turn it off again and it will not automatically turn itself off once a fault is cleared.

[GiveMeABreak]

You can't turn off any faults if there is an underlying issue, as it will just reappear. The Airbag ECU does a system check on ignition start, and if all is ok will extinguish after a few seconds, except where the passenger airbag has been deactivated.

But as mentioned, you need a diagnostic tool that can read all the systems, which a generic fault code reader won't always be able to do. So if the airbag light is on, then there is a fault code recorded, it's just your reader isn't able to pick it up. I suggest you try and get the the fault code here first, then I may be able to provide an idea of the problem.

[wheeler]

I would have thought that if the tool could read the fault it would clear it?
Id try disconnecting the battery for a couple of minutes. It will require the radio code if you still have original radio fitted.

[GiveMeABreak]

Reading the post again, as it's not very clear, I suspect it's to do with the steering wheel angle sensor - which if he has ESP will need calibrating if removed, which may be why the airbag warning is lit. You'll need a diagnostic tool capable of doing this though.

[wheeler]

Cant think ive ever seen a mk1 C1 with ESP. If they were ever available with ESP it must be pretty rare.

[GiveMeABreak]

So I should of checked earlier from the VIN, but although these were available with ESP, this one doesn't have it, so no steering wheel angle sensor in the steering wheel clock spring.

You have variable power steering and there is one type of ECU for all with a torque sensor - but I can't see the relationship with airbag faults regarding this... I think we need a bit more clearer detail.

Are you saying you replaced the suspension spring?
If so and any work was done on the steering rack, the the torques sensor will need calibrating.

[JOE+TECH]

To make it a bit more clear
1 The air bag fault light was on, checking with diag tool fault code B 1801 ( driver level1 airbag ignition module open citcuit ) present
Fitting new rotary coupling below steerirg wheel ( clock spring) cleared fault with diag tool = no faults now in air bag ecu.
2 Now no faults recorded in air bag ecu= but the air bag fault light is still on instrument
Put faulty clock spring back on fault code B1801 returned,Refitted new clock spring fault can be cleard
That is why I sugested if you could supply wiring diagram for air bag system + instrument I could check the communication between
air bag module and instrument, As I think there must be a measage sent to the instrument to turn off air bag light with no faults present
Diag tool dose not read any data, fault codes ect from instrument I dont think instrument has any ecu present
In air bag ecu only data shows components fitted, Drivers air bag , pass air bag, pretensioner drivers side , pretensioer pass side
very simple system
Car has no esp
Hope this helps, and a wiring diagram would be nice
Thank Joe

[wheeler]

Its a pretty basic system.
0004 is the instrument panel.

[JOE+TECH]

Thanks Wheeler for wiring diagram will get it checked tomorrow and report back
Thanks Joe

[JOE+TECH]

Thanks again WHEELER for wiriing diagram checked wire from airbag ecu to instrument all ok
Changed air bag ecu, fixed the fault
Thanks Joe