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airbag and mot
graememk - 14/4/14 at 05:22 PM

quick one for mot testers and those in the know.

steering wheel Airbag light on the beetle, ordered new clock spring but the mot ran out last week so I need an mot on it tomorrow

I'm told the yellow airbag warning light isn't an mot fail is this true ?

thanks in advance

Graeme mk

steve m - 14/4/14 at 05:30 PM

An airbag warning light IS A FAIL,
however, the ones that I have fixed, have all been seat airbags, and the connectors under the seat

wait 30 mins after car last used
pull the wireing loom plugs apart under the front seats
a quick spray of contact cleaner
put plugs back together

job done

steve

Slimy38 - 14/4/14 at 06:13 PM

Graeme, I think you might be thinking of the engine light, that isn't a fail.

britishtrident - 14/4/14 at 06:47 PM

quote:
Originally posted by graememk
quick one for mot testers and those in the know.

steering wheel Airbag light on the beetle, ordered new clock spring but the mot ran out last week so I need an mot on it tomorrow

I'm told the yellow airbag warning light isn't an mot fail is this true ?

thanks in advance

Graeme mk


In 95% of cases SRS warning lights are triggered by iffy connections,. Broken clock springs are uncommon unless damaged by removing/refiting the steering wheel.
If you have a fault code that points to the steering wheel bag then check and clean the connector, if you don't have a fault code or just a general fault codefor the SRS then check the connectors under the seat first.

On start up the SRS ECU runs a self check in all the systems I have worked it checks each air bag detonator for a resistance of between 100 and 400 ohms, the self check can be fooled (for test purposes only nb. - I am not telling you to by pass an important safety system). by 200 ohm resistor.

Do not try testing the resistance of any part of an SRS system with a DMM in case you trigger a detonator.

Always disconnect the battery and allow 20 minutes for system to discharge before working on SRS systems.

[Edited on 14/4/14 by britishtrident]

NigeEss - 14/4/14 at 06:59 PM

Airbag on light is a fail.

Airbag light not functioning isn't

AndyW - 14/4/14 at 07:00 PM

Interesting as our megane passed MOT with airbag light on. Probably because its a Renault and they always have some kind of warning light on, even when working fine.

Luckily my mrs smashed the front off in a car park so when we had it repaired we then got a new clock spring and job jobbed....

theprisioner - 14/4/14 at 07:27 PM

Can you help me here, what is a clock spring in an air bag?

jollygreengiant - 14/4/14 at 07:37 PM

quote:
Originally posted by theprisioner
Can you help me here, what is a clock spring in an air bag?


Its the steel wound spring that carries the electrical link between the fixed column housing and the rotating steering wheel, so that electrical contact is continuous and NOT reliant on carbon brushes and brass slip rings.

balidey - 14/4/14 at 08:27 PM

I've heard that some people disconnect the clock spring at the column end, then insert a resistor into the plug. This fools the ECU into seeing the airbag.
Obviously not something you want to do, or condone, but if you are desperate to get the MOT done, then rectify the problem when the correct part turns up....

britishtrident - 14/4/14 at 08:47 PM

quote:
Originally posted by NigeEss
Airbag on light is a fail.

Airbag light not functioning isn't


No that is definitely not the case you cannot simply take the bulb out.

See: http://www.ukmot.com/mot%20manual/index.asp?MOT_Section=Supplementary%20Restraint%20Systems%20(SRS)&MOT_Number=5.4

phil clegg - 14/4/14 at 09:49 PM

when I test a vehicle I check the function of the light,there is 2 options,fail for being lit indicating a fault,2advise for non function of light,another option is airbag removed for motorsport purposes and is therefore not required along with abs etc,any other testers read it different as we al have our opinions...

NigeEss - 15/4/14 at 06:42 PM

quote:
Originally posted by britishtrident
quote:
Originally posted by NigeEss
Airbag on light is a fail.

Airbag light not functioning isn't


No that is definitely not the case you cannot simply take the bulb out.

See: http://www.ukmot.com/mot%20manual/index.asp?MOT_Section=Supplementary%20Restraint%20Systems%20(SRS)&MOT_Number=5.4




The MOT tester I always use said non functioning bulb is an advise, as mentioned by Phil above.

[Edited on 15/4/14 by NigeEss]