# Airbag System Fault - N253



## tonis555 (Sep 18, 2012)

Hi everyone :wave:

can someone help me with airbag problem:

*

Control Module Part Number: 3D0 909 601 A 
Component and/or Version: Airbag 8.4E 0506
Software Coding: 0241705
Work Shop Code: WSC 01065
1 Fault Found:
01590 - Igniter for Battery Disconnect (N253)
001 - Upper Limit Exceeded
*

how to solve this problem?


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## PanEuropean (Nov 3, 2001)

N253 is the explosive disconnection device at the starter battery positive terminal.

Go and physically inspect this component - my guess is that you will find that the yellow wires leading to it are somehow not properly connected to the airbag control system.

If the vehicle has a history of being in an accident, it is also possible that this device has 'fired', although that is unlikely because if it did fire, the right hand side battery positive terminal would then be disconnected from the vehicle electrical system.

Michael

*N253 Component Location*


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## tonis555 (Sep 18, 2012)

thank you Michael for quick answer. today I dismantle everything to look or everything ok. seems like it's ok. so I puted everything back but it's the same  what next?


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## Paximus (Aug 26, 2011)

Did this appear when you changed the battery?

If you clear the fault using VCDS, how much time passes before it comes back?

Chris


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## tonis555 (Sep 18, 2012)

Paximus said:


> Did this appear when you changed the battery?
> 
> If you clear the fault using VCDS, how much time passes before it comes back?
> 
> Chris


it been before changing the baterry. 

It passes about 1 second and it comes back


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## jyoung8607 (Feb 14, 2006)

tonis555 said:


> it been before changing the baterry.
> 
> It passes about 1 second and it comes back


Michael and Chris already have you on the right track.

The airbag module always monitors all the igniters around the system - eight(?) airbags, two seatbelt pre-tensioners and the battery separator relay. If it sees the right resistance value, it knows the igniter is still there on the other end, so the pyrotechnic device is probably okay as well. The error you see in VCDS means the airbag module sees resistance too high for the battery separator. This can mean the igniter is defective, or possibly broken wiring.

You probably need to replace the battery separator, the piece you removed and showed us. Please be very careful when you're working on it. Whatever's in there is designed to crack that battery lug in half, and static electricity could set it off.

Jason


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## tonis555 (Sep 18, 2012)

thank you for answers :thumbup:

next question is maybe somehow I can "walk around" this seperator?  (I don't need him, I just need working airbag's  )


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## PanEuropean (Nov 3, 2001)

tonis555 said:


> next question is maybe somehow I can "walk around" this separator?


Well, from strictly a troubleshooting (in other words, fault isolation) point of view, I suppose you could complete the circuit by disconnecting the squib (the separator) - unplugging it, in other words - and seeing if providing continuity across the terminals that normally connect to the ssquib would clear your fault code. If doing this does clear the fault code, then you will know that the separator is defective.

The purpose of that separator is to disconnect (cut off) the high current from the line that leads from the starter battery up to the starter in the front of the car. If you have an accident - which would be implied by one or more of the airbags firing - it is very desirable to have the current on that big line cut off, because if the line is damaged in the accident (highly likely if it is an impact to the right side of the car), you could get a lot of sparking and arcing that could cause a fire.

I've attached a wiring diagram of the airbag system for your reference. The N253 is found on tracks 95 and 96 of this diagram. The connector T2SG is probably the large yellow plastic connector nearby the positive battery terminal of the right battery.

Please take Jason's warning about static electricity seriously - be sure you are properly grounded (for example, with a static wrist strap, or at a minimum, by momentarily touching the negative battery terminal of the vehicle first) before you disconnect this connector.

*DO NOT, UNDER ANY CIRCUMSTANCES, USE A MULTIMETER TO CHECK RESISTANCE ACROSS THE SQUIB ITSELF!!! IF YOU DO THIS, THE SQUIB MAY DETONATE.*

Michael


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## WillemBal (Nov 20, 2010)

Hi Tonis,
It looks like this battery separation already did its job. The little hole in the component in your hand was supposed to hold the battery cable:



The little yellow thing where the wires lead to is actually the connector, previously tied to the detonator. This detonator is presumably secured by the 8 mm stud. This one looks like a black square and is also missing from your collection of components. I believe that the actual pyrotechnic charge somehow was integrated in yet another black component, about 25 mm in diameter, which holds the actual battery cable. 



> next question is maybe somehow I can "walk around" this seperator?  (I don't need him, I just need working airbag's  )


First of all, you need a sound connection between your starter battery and the starter motor. As Michael indicated, there is a chance that a fire can occur when you have a collision on the right side or even the front of the car. There is no fuse nor switch in the plus starter battery cable, all the way to the starter motor, so if a collision pinches the plus wire, nasty things can happen, ranging from a fire up to an exploding battery.



> today I dismantle everything to look or everything ok. seems like it's ok. so I put everything back but it's the same  what next?


There are some pretty nice photo's of the entire assembly in this thread:
Battery-replacement-procedure

I bet that the big black, round part between the cable and the battery clamp is missing. It is not a DIY job to fix this so that the original function of the component is restored. It is better to leave this to a VW authorised dealer. It is a very special component, which is not yet very common on cars and rarely needs replacement. So my guess is that only VW dealers of Touaregs and/or Phaetons are aware of the replacement procedure.

Willem


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## PanEuropean (Nov 3, 2001)

Hi Tonis:

I agree fully with Willem's analysis above, especially his caution about getting this part replaced at a dealership.

I have attached a PDF below that explains the process involved in replacing the positive battery terminal detonator assembly. Note the great number of red, bold-text warnings in this documentation. It's not the usual American lawyer yada-yada (caution, coffee is hot) - clearly VW is very concerned about accidental or unintentional discharge of the detonator when it is being installed.

If your car has no known accident history, then it is safe to assume that someone screwed up in the past and accidentally detonated the device in your car.

Michael


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## tonis555 (Sep 18, 2012)

thank you all for answers :thumbup: I think I will go to vw dealer to talk about changing this part


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## Paximus (Aug 26, 2011)

Just out of interest, does the above discussion imply that the car is being operating with the right hand battery disconnected?

After a brief read of the SSPs I presume this would work, after a fashion.

Chris


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## tonis555 (Sep 18, 2012)

can someone write a battery cut-off (saperator) vw part number?


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## tonis555 (Sep 18, 2012)

Paximus said:


> Just out of interest, does the above discussion imply that the car is being operating with the right hand battery disconnected?
> 
> After a brief read of the SSPs I presume this would work, after a fashion.
> 
> Chris


this is interestig for me also


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## Paximus (Aug 26, 2011)

Hi,

The Phaeton 'pyrotechnical battery isolator' only lists as part of the battery cable assembly, the exact part number depends on your engine code (BMK engine cable is 3D1 971 228A for example). It's around $350. It's just possible you might find one on a non-crashed parting car, since they are probably a nuisance to import as spare parts because of the explosive element.

It's possible the Bentley Continental 'cable battery isolation igniter' part 3W0 971 349K might fit but it costs $900 in some parts of the world so that's not much help.

Is there a 3D0 (Phaeton) number written on your old one, separate from the cable assembly?

Chris

Edit - sorry if anyone got wrong email updates on this posting! Anyway, the part number for the pyrotechnic cable for a left-hand drive 3.2L V6 petrol with 2 batteries should be 3D1 971 228 or possibly 3D1 971 228B unless it is long wheel base.


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## tonis555 (Sep 18, 2012)

thank you for answer. my code is 3D1 971 228B. Next question  I know few phaeton's selling in part's whithout accident's. but 3L diesel. does it fit for my 3,2 v6?


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## Paximus (Aug 26, 2011)

3.0TDI uses 3D1 971 228A. I think all the igniters will be the same part, only the cable assembly might be very slightly different.

Chris


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## zhikang (Sep 1, 2015)

the wire is connected but still cant start


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## Paximus (Aug 26, 2011)

Hello zhikang,

Welcome to the forum!

Please give us more information about your problem. Is it either (a) that your Phaeton will not operater the starter-motor, or (b) that the starter-motor operates OK but the engine will not fire up?

Which model Phaeton do you have, and what country is it in? Do you have a VCDS fault code scanner (or another type of VW scanner)?

Chris


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