Welcome to 911UK
The only place for Porsche, 911uk is the definitive enthusiast and resource site for the Porsche 911.
Registration is fast, simple and absolutely free, so join up today for full access to the site and benefit from latest member offers.

Porsche Classifieds
Porsche Buyers Guides
Sell Your Porsche on 911uk
Create a Free Classified Advert
Search Ads
Classified Adverts FAQ
Trade Classified Information
Buyer & Seller Fraud Protection
Pre Purchase Inspection (PPI)
Porsche Car Sourcing
Porsche Cars Wanted
Model
Stock
Porsche 911
991 : 2011- 3
997 : 2004- 59
996 : 1997-2005 45
993 : 1993-1998 9
964 : 1989-1993 1
Carrera 3.2 : 1983-1989 0
Carrera SC : 1977-1983 0
930 Turbo : 1975-1989 1
Early 911 : 1964-1977 1
Porsche Other Models
Classic : 1950-1965 1
Boxster : 1997- 15
Cayman : 2005- 12
Cayenne : 2003- 10
Macan : 2014- 2
Panamera : 2009- 0
912-914-924-928-944-968 6
959 - CarreraGT - RaceCar 1
Car Parts For Sale & Wanted
Other Items For Sale & Wanted
Wheels Tyres For Sale & Wanted
Number Plates For Sale Wanted

Porsche Services
Porsche Body Shop Repair
Paint Protection & Body Wrapping
Porsche Classic Insurance
Porsche Classic Parts
Porsche Classic Restoration
Porsche Design Collection
Porsche Engine Gearbox Rebuild
Porsche Heritage & History
Porsche News
Porsche Picture Gallery
Win a New Porsche 911

Porsche Parts
Body Parts, Body Styling
Brakes, Clearance
Electrical, Exhausts
Engine Cooling, Engine Electrical
Engine Rebuild, Heating Cooling
Interior Incar, Lighting
Rubber Seals, Service Parts
Steering, Suspension
Transmission, Workshop Tools
Early 911, 911 - 930, 928 - 968
964 - 993, 996 - 997, Boxster
Cayman, Cayenne, Panamera

Porsche Model Range
911 [991] 2011-Current
Porsche 911 [991]
911 [997] 2004-Current
Porsche 911 [997]
911 [GT] GT1-GT2-GT3
Porsche 911 [GT]
911 [996] 1997-2005
Porsche 911 [996]
911 [993] 1993-1998
Porsche 911 [993]
911 [RS] RS-RSR
Porsche 911 [RS]
911 [964] 1989-1993
Porsche 911 [964]
911 3.2 1983-1989
Porsche 911 3.2 Carrera
911 SC 1977-1983
Porsche 911 SC
911 [Early] 1964-1977
Porsche 911 [Early]
Boxster & Cayman
Porsche Boxster & Cayman
Cayenne & Panamera
Porsche Cayenne & Panamera

911uk Site Partners

Post new topic   Reply to topic
Author Message
pietrzj
Monza


Joined: 19 Mar 2014
Posts: 207



PostPosted: Fri May 05, 2017 6:35 pm    Post subject: Airbag warning and OBD one Reply with quote

All,

For some time I have had a warning light that goes out after about two minutes and I need to fix it.

I have an OBD2 s/w pack and interface cable that I bought a few years ago an have never used (cheap from ebay, which I bought for a 51 clio I had), but I noticed the connector is the same type as the 993.

As my MY is 1994 and the connector cover says OBD not OBD2, I am assuming if it works the info I get will probably be limited. I am hoping it will tell me which airbag is reporting a fault. Failing this I am guessing I will have to disconnect the battery, wait a bit and access the orange conector to disconect the steering bag an insert a 2.8 ohm resistor in its place to see if it is that one that is keeping the light on for two minutes. Then move to the passenger unit if there is no change.

Is this the best DIY approach or are there other techniques I could consider. I have an MOT coming up so want to know where the fault is rather than replacing both bags.

Some other threads also suggest the cause could be dry solder joints on the clock PCB? Anyone got any details about this?

I am handy with a soldering iron if that s the route I need to take.

Any help gratefully received.

p.s I have tried the old ignition on with foot on throttle method, but no flashing lights that relate to airbag faults.

If all else fails its the dreaded Porsche Main Dealer

Jan
 
  
View user's profile Send private message
   
Demort
Paul Ricard


Joined: 21 Mar 2015
Posts: 3247
Location: Sussex


PostPosted: Fri May 05, 2017 7:47 pm    Post subject: Reply with quote

I would just say get an indy to read out the fault codes for you , it will be far quicker and cost effective i would think and after that you can choose to repair it yourself or get a quote from them.
_________________
Mechanic

7pm - 9pm
 
  
View user's profile Send private message
   
NottsRS
Barcelona


Joined: 11 Jan 2009
Posts: 1316



PostPosted: Fri May 05, 2017 8:51 pm    Post subject: Reply with quote

ToreB might be your man here. His T-OBD diagnostic interface is a useful bit of kit. A bit of a faff to set up the downloadable rennlist software but once sorted you have easy access to the Motronic, CCU, SRS Airbag, Alarm, TIP ECU's and can view and reset all faults.

https://www.bergvillfx.com/index.php/products/obd-diagnostics/t-obd-diagnostics-for-porsche-968-964-and-993.html

Good luck sorting the issue out Thumb
_________________
993 RS | Riviera Blue | Lightweight
964 RS | GP White | Lightweight
993 4S | Viola Metallic | Factory Non Sunroof | [Jan'09-Mar'16]
 
  
View user's profile Send private message
   
ToreB
Approved Trader


Joined: 13 May 2010
Posts: 531
Location: Oslo, Norway


PostPosted: Sun May 07, 2017 7:34 am    Post subject: Reply with quote

NottsRS, thank you for your reference.

An off-the-shelf OBD reader/scanner will only at best be able to communicate with the Motronic engine management system in the 964/993.
Don't bother with the OBD1 or OBD2, this is not the problem here. If you have the round 19-pin OBD connector you will need a 19-pin adapter to use a OBD tool. Beware, most such adapters on eBay/Amazon/elsewhere are wrongly connected. I sell a proper cable made according to Porsche specs.

There's only a handful of systems that can do all the OBD-connected things in our cars. (Motronic, ABS, air bag, alarm and climate control)
*The Bosch Porsche "hammer" (KTS 301) or later Bosch Porsche tools as PST2 or PIWIS
*Freeware Rennlist Scantool Windows software (serial port adapter as the T-OBD needed)
*Durametric Windows software with a proper (original) serial cable
*Jenniskens OBD UDT/PDT999 diagnostic tool

Cheers,
Tore
_________________
'95 993 C4

Bergvill F/X
Porsche electronics specialists, products and repair services.
 
  
View user's profile Send private message Send e-mail Visit poster's website
   
pietrzj
Monza


Joined: 19 Mar 2014
Posts: 207



PostPosted: Sun May 14, 2017 9:13 pm    Post subject: Reply with quote

Thanks all. My car does have the OBD2 connector at least. I have now made the situation worse by inserting resistors instead of the airbags. Now the light comes on on the check, goes off briefly (less than a second) the comes on all again - permanently. Have put everything back to normal and will try to see if at least i. An get back to it only being on for two minutes.

Will ring the indy tomorrow, dont have long until the MOT test!!!
 
  
View user's profile Send private message
   
ColinC
Imola


Joined: 16 May 2013
Posts: 855
Location: Sunny Central Scotland


PostPosted: Mon May 15, 2017 12:00 am    Post subject: Reply with quote

I have a similar problem in that the airbag warning light does not go off for about two minutes after starting the car. I have installed a Cup Steering wheel and deleted the air bag and thought the resistor would remedy the situation as I thought the issue was the air bag itself but alas no......it always goes out after 2 mins.

Spoke to our Rennlist Buddies and as the solder lines at the rear of the clock module detoriate this is one of the symptoms - fix is the responder the connections - haven't attempted it yet and won't as my soldering skills are terrible!

Let me know how you go.....
_________________
94 993 C2 - Black with Marble Grey Leather
 
  
View user's profile Send private message
   
pietrzj
Monza


Joined: 19 Mar 2014
Posts: 207



PostPosted: Mon May 15, 2017 5:07 pm    Post subject: Reply with quote

Well I think my clock connections are good.

Does anyone know what actually triggers the bags to go off? I assume there would have to be some sort of switches (inertia?), or is it triggered off a rapid decrease in speed? The only incertain connections in the wiring diagram seems to connect to the alarm system and imobalizer.

I am sure my old clio had bright orange switch units around the car that would trigger the airbag if they were hit.

No such thing can be found so far oin the 993 so maybe they are integral with the bags?

I am running out of time here, I don't want to take it to the indy only for them to scratch their heads if I can help resolve it in this forum.

I am sure it would take them hours and hours to find a clock dry solder joint for example, but if I can rule out as much as possible that will save them time (and me money).

Jan
 
  
View user's profile Send private message
   
pietrzj
Monza


Joined: 19 Mar 2014
Posts: 207



PostPosted: Mon May 15, 2017 5:12 pm    Post subject: Reply with quote

Just found this...

The Boxster also got a new airbag control unit like the 993’s, with its internal MEMS accelerometer crash detection. The control unit will store up to ten faults, with a start-and-stop log kept for each fault. Data can be accessed and downloaded with the PST-2 or PIWIS testers. As in the 993, the Boxster control unit does not need to be replaced until the airbag has been triggered three times or if its fault memory cannot be deleted.
 
  
View user's profile Send private message
   
pietrzj
Monza


Joined: 19 Mar 2014
Posts: 207



PostPosted: Mon May 15, 2017 6:13 pm    Post subject: Reply with quote

Or maybe the trigger is in the control unit Very Happy
 
  
View user's profile Send private message
   
Demort
Paul Ricard


Joined: 21 Mar 2015
Posts: 3247
Location: Sussex


PostPosted: Mon May 15, 2017 7:51 pm    Post subject: Reply with quote

I dont really know 993 systems but on newer cars if theres a fault with the airbag system the light stays on and will stay on all the time there is a fault code even if the system has been repaired.

i thought it was a one time use airbag control unit on the 993 but the boxster onwards was a 3 time use Dont know

It really needs a fault code read out to go further .. a code or lack of one helps point us in a direction .

From the description you have given of the light switching off after 2 mins then i would lean towards it being the control unit .. i know 996 onwards and they do give strange faults at times .

I mentioned on your other post its all in one unit now .. not seperate .

DO NOT what ever you do remove this unit with the battery connected or ignition on !
_________________
Mechanic

7pm - 9pm
 
  
View user's profile Send private message
   
ColinC
Imola


Joined: 16 May 2013
Posts: 855
Location: Sunny Central Scotland


PostPosted: Tue May 16, 2017 8:59 am    Post subject: Reply with quote

pietrzj wrote:
Well I think my clock connections are good.

Does anyone know what actually triggers the bags to go off? I assume there would have to be some sort of switches (inertia?), or is it triggered off a rapid decrease in speed? The only incertain connections in the wiring diagram seems to connect to the alarm system and imobalizer.

I am sure my old clio had bright orange switch units around the car that would trigger the airbag if they were hit.

No such thing can be found so far oin the 993 so maybe they are integral with the bags?

I am running out of time here, I don't want to take it to the indy only for them to scratch their heads if I can help resolve it in this forum.

I am sure it would take them hours and hours to find a clock dry solder joint for example, but if I can rule out as much as possible that will save them time (and me money).

Jan


964 and 993 system same same - some further reading

https://rennlist.com/forums/964-forum/23104-clock-repair-airbag-light-diy.html


http://p-car.com/diy/clockrepair/
_________________
94 993 C2 - Black with Marble Grey Leather
 
  
View user's profile Send private message
   
stichill99
Monza


Joined: 03 Nov 2013
Posts: 200
Location: Scottish Borders


PostPosted: Tue May 16, 2017 12:54 pm    Post subject: airbag Reply with quote

3 years ago I had airbag light on and it was knackered control module which was replaced by one with a 996 part no. Not cheap at £540
 
  
View user's profile Send private message
   
Demort
Paul Ricard


Joined: 21 Mar 2015
Posts: 3247
Location: Sussex


PostPosted: Wed May 17, 2017 7:56 pm    Post subject: Reply with quote

Just a thought but i was replaceing an indicator stalk on a 993 today and theres an earth wire that goes from the clock spring to the wheel .. ive seen this break in the past and cause intermitant airbag faults as it can make and break a connection ..

Pretty quick check .. just undo the airbag screws lift it up and check the brown wire .. T30 torx are the airbag screws and if your going to disconnect the airbag then battery disconnect first Smile
_________________
Mechanic

7pm - 9pm
 
  
View user's profile Send private message
   
pietrzj
Monza


Joined: 19 Mar 2014
Posts: 207



PostPosted: Wed May 17, 2017 10:14 pm    Post subject: Reply with quote

thanks Demort, I will check it this weekend
 
  
View user's profile Send private message
   
pietrzj
Monza


Joined: 19 Mar 2014
Posts: 207



PostPosted: Tue May 23, 2017 4:49 pm    Post subject: Reply with quote

Success!

Took it to my IPD and they detected the following codes:
AIRBAG:
19 - Airbag warning light
17 - Power supply
5 - Ignition circuit, passenger
2 - Ignition circuit, driver

Also a few codes in other areas too (I will raise a new post)

They cleared the codes and the alarm light for the airbag system works correctly.

Thanks for your help.
 
  
View user's profile Send private message
   
Demort
Paul Ricard


Joined: 21 Mar 2015
Posts: 3247
Location: Sussex


PostPosted: Tue May 23, 2017 8:00 pm    Post subject: Reply with quote

Just in case the fault returns then concentraite on the airbag light , power supply happens with a battery disconnect and wont bring on the light .. the other 2 are im guessing where you had the resistor in them .
_________________
Mechanic

7pm - 9pm
 
  
View user's profile Send private message
   
Display posts from previous:   
Post new topic   Reply to topic   All times are GMT - 11 Hours
Page 1 of 1

 
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
You cannot post calendar events in this forum