Seat Belt Tensioner - Airbag Light

Panda996 · 2 Oct 2019

Hi
I am working my way through tracing out the dreaded Airbag warning light!
Following a trip to the Precision open day in the summer, I was advised to check the drivers side seat belt reel. (thanks guys)
So, having now failed an MOT I eventually got round to stripping out the side panel, I can see the belt reel and have disconnected the wires.
The question is now how to identify a faulty reel?
The wiring diagrams show resistances on the USA models, but a blank box on ours in UK.
To save me taking the passenger side apart tomorrow to compare readings, can anybody tell me the expected resistance reading for the 2 pin tensioner?
It looks like I have a closed circuit zero (or minimal) ohms... does this prove knackered?.. or prove ok? (I was expecting open circuit to be knackered)
Any help much appreciated as always.
cheers
Paul

deMort · 2 Oct 2019

As i understand it the seat belt pulls closed in the event of an accident .. if it's a pyrotechnic device which i think it is then you CERTAINLY don't want to be using an ohm meter on it as it may deploy .

I've never tried this anyways .. when it comes to airbag systems you have to be very careful .

At OPC we had several boxes we used to plug into the wiring to simulate the correct value .. if the code cleared then it proved it was Faulty .. there was no resistance values listed though from what i remember .

I'm not sure what the fault code was as i think Gron did your check but if it says a seat belt then its either that .. the wiring or the control unit with the seat belt being the most obvious .. can you post the fault code so i can look into it please .

deMort · 2 Oct 2019

Read post above first ..

A separate story .. i do like telling a story

Everything i've ever been taught has basically said you don't use an ohm meter on any airbag component as it can deploy ..

A Long time ago in a distant galaxy far .. far away and in my Pre Porsche days ..

I had replaced a passenger airbag on a Rover SDI i believe it was .. this is a large airbag .. very large ..

We can't just throw it away as its an explosive device so i had to deploy it.

I put the airbag in a toilet room , ran some wires under the door thinking i could trigger it in there and i would be safe ... yup i was young and stupid at that point .. sigh ..

I connected and ohmmeter to the wires .. at the same time trying to put my fingers in my ears .. like that was going to work ...

It didn't trigger .. somewhat confused i thought sod it i'll use a battery so found an old one .. had about 11 volts in it and did the same .. it didn't trigger ..

At this point i'm confused .. everything i'd read said it should have gone off ..

so I got a battery that was on charge .. 13 volts .. and connected that .. thinking if this doesn't do it then i have no idea ...

It went off .. erm .. oh boy did it go off .. an explosion in a small room is rather loud .. an explosion of a large airbag next to a toilet does a wee bit of damage when it bounces around the room , not bolted down was it .. sigh ..

Toilet was destroyed , the sound totally defendened me .. a ringing is all i could hear ..

At this point not only did everyone in the building come running but at least 5 members of the public 20 yards away in the street also appeared in the workshop wondering what the hell had happened ..

me .. being totally deaf at this point sat on the floor trying to explain it with water from the blown up toilet seeping under the door and me sitting in it !

logically it should have gone off with an ohm meter ...

logically i shouldn't have been so stupid ..

These days .. i'm a little bit more careful when setting one of these things off

An ohm meter can still trigger one though .

Panda996 · 3 Oct 2019

Hi Iain, thanks for quick reply.
Yes it was Gron who did the car check. But you did join us half way through after I reintroduced myself as the Silver Targa person who came to your house in Brighton about 6months earlier for you to check my Targa roof motors. You might also remember that while you were doing that, you commented on wet mats in rear offside footwell, hence all pointing to a leak down the drivers side rear window that may have dropped onto the seat belt spool.
The code on the readout was B05 part number 99661821901
I understand about not testing the spool with a multimeter. But without knowing what else to plug in to test if faulty then it seems only option is to replace and hope it is the cure? Seems an expensive trial and error game!
I'll try post a pic of spool when I get to my P-C To confirm which type.
Cheers
Paul

Panda996 · 3 Oct 2019

Targa 2003 Drivers side.
Might look corroded but connection terminals are clean.

Panda996 · 3 Oct 2019

Computer Read Out

The return of Marty Wild · 3 Oct 2019

Good work, Iain, we've all played with explosives in the past haven't we?! :?:

Before it became non P.C. :lol:

deMort · 3 Oct 2019

Yes indeed .. it was damp inside .. i remember now .. im afraid ive seen 2 more since that day at my house along with a few other cars ..

My memory is shocking at times .. sorry young man .

Ok .. the porsche way is there is a seperate box .. which basically has resistors in it which you plug into the item then see if you can clear the fault code ..

It is indeed a resistance that the car sees but there is no record of what the actual resistance for each component is .. Porsche basically don't tell us .

OHM meter is a bit iffy is the point i wanted to make .. if it deployed in your hands then you might get hurt .

Ok .. so how do we prove it without the porsche tools ..

At work i would just fit a spare seat belt , and see if the code cleared .. if it did then i would replace the seat belt ..

You don't have a spare but you do have a passenger seat belt ...

i honestly have no idea if the wiring plugs are the same but im going to assume they are .. remove the passenger belt and plug it into the drivers and see if that side clears the code .

If you don't have a fault code reader though then this wont work .. you have to see the code clear ... airbag light can only be turned off with a code reader .

Normally i would say it's going to be the seat belt ..

My concern with yours is it was rather wet .. im wondering if its a corroded wiring connection .. not at the seat belt but at the harness connections lower down and slightly in front of the seat belt as that's where i assume the wiring from the seat belt runs through on its way to the airbag control unit .

Do you have a code reader for the airbag ?

Your last option is as you said .. compare readings from the other side .. for my part and obviously being in the trade i will have to say don't do it .. it may be fine but i have to say it may not be and you may get hurt .

That is i'm afraid my disclaimer .

Panda996 · 3 Oct 2019

Thanks Iain, the info on the connector below the seat belt might well be very useful. Might be good idea to test the full length of the 2 cores from the Airbag control box through to the seat belt, to make sure they are good.

Having already taken the foolish move to measure the spool at zero ohms (approx.) would it be reasonable to suggest the 'Special' Porsche secret box they use to plug in and test might just be a shorted out 2 pin connection?
Or if there is a specific resistance, then my zero measurement shows its knackered?
What I need is someone brave enough to put a crash helmet on and measure a good seatbelt spool and tell me what they find!!..any volunteers??
Unfortunately I don't have a reader any where near good enough to expect it to reset the system. I was hoping to find something obviously faulty and change it before taking to nearest Indie (9E) for a reset.
BTW, did the fault code tie in with seat belt? or was it just a general airbag system code?

Has anybody any experience of this outfit below?
They seem to know all about

https://www.ebay.co.uk/itm/Porsche-...sh=item3fcd50e8ec:g:LbUAAOSwVW9bs7G0#viTabs_0

Thanks again
Paul

deMort · 4 Oct 2019

Im afraid im not sure just what Gron has printed out there as it's not a list of fault codes .. looks more like faults and identifications of systems so not much help ... he must have printed the wrong page .

I've had to trawl through many fault codes to find what i assume is your code though ... images bellow for the test plan .

Going to kick Gron for making my life harder on Monday i can tell you lol .

off hand .. there should be some sort of resistance .. a connected wire ( zero ohms ) is not going to trigger it or indeed anything .. it's just a wire going in and out ...

Basically every item that does something on any car will have a resistance value .

i know on 997 we can see the resistances of the components on a tester .. there is nothing that's just a zero ohm circuit and let's face it the systems are pretty similar .

Off hand then zero ohms to me indicates its not correct .. but i have no real reference so i'm just going by logic .

In short i can't say if its faulty or not .. but it doesn't seem correct to me .

Ebay link is for accident damaged belts that have been deployed .. they don't list faults so might not be able to fix it .

An idea of the tool cost is here ...

https://www.ebay.co.uk/itm/PORSCHE-...411870&hash=item1ccc8384a7:g:2WsAAOSwNRJcio3d

Panda996 · 22 Oct 2019

I will continue this thread until problem resolved if that's ok, as might help if anyone is searching similar problems.
I came to the conclusion that the seat belt pre tensioner contacts are bridged out once the connector is removed. I guess this is for safety purposes so that a voltage cannot be accidentally applied..
So my initial test readings of 'Short' zero ohms (or the test leads resistance) would be correct for any belt with a pre-tensioner.
The way to test is to gently push the bridge (which is spring loaded) away from the terminals and then take an Ohm reading, which according to various you-tube clips say a good belt is about 2-3 Ohms.
Mine tested at 2.2 Ohms by gently pushing a bare cotton bud inside to push one side of the bridge away from the terminal.
Here's a clip to show what to do and and followed by a couple pics of my belt.

https://www.bing.com/videos/search?...EA9FB82ABFCBD77E7459EA9FB82ABFCBD&FORM=VDQVAP

Unfortunately for me, it still means I haven't found anything wrong yet, so still searching. Next task will be to try find the common connector blocks between the belt and the control unit and test for continuity/earth.
At least the sun is shining in Sunny Reigate today!

Panda996 · 3 Nov 2019

Re-tested today.
The fault code is indeed 06 "Belt Tensioner, Driver"
Used an Autel MD802 MaxiDiag Elite, which seems to work fine.

Just a thought...I don't suppose the 'Drivers' side is the Left for us in UK?

deMort · 3 Nov 2019

Probably not what you want to hear but yes it is possible .. door locks used to flag up as the wrong side.

I don't remember it recently though so it might have been a software update on the tester that has stopped it .

Either way i'm afraid it's something you need to bear in mind .

Did you try swapping them side to side ?

Panda996 · 3 Nov 2019

Well if its possible that the Drivers side means the left, then that's what I will Inspect/test as my next job.
Now I have got the hang of removing and replacing the rear panels it shouldn't be a big deal. And if I find nothing obvious then will swap the connections over side to side and see if the fault code changes.

deMort · 3 Nov 2019

I expect it will .. if it doesn't then the issue is not with the seat belt.

If it does and again i'm not condoning this but the test on the belt you have already done should be different on the faulty side ..

Once again .. this test worries me .. goggles and a face mask is all i can suggest

but i'm basically saying this is not a test you should do .

Concerned !!!

Seat Belt Tensioner - Airbag Light

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