07C4S

Bought the car a couple weeks ago w/ the SRS light on. I got the Bergvill cable and ScanTool4 software. Reset the light - stayed off for about a week. Came back on while driving 2 days ago. Checked the battery - 5 years old but voltage was OK but I replaced it anyway. Alternator output is good. Light keeps coming back on - instantly after the reset.

I've searched the forums and looks like checking the clock spring and also eliminating the airbag as the issue w/ a resistor are the next steps. Looks easy enough.

One question before I do so - in all the posts I found there was very little reference of the ACTUAL error code along with the fix.

I'm only getting fault 2 "Driver ignition circuit to + or 0 V". Still proceed with the clock spring and resistor test or does this specific fault point anywhere else?

Thanks

pp000830

The wording sounds like the detonator circuit to the air-bag explosives has an issue. If you put in the resistor bypass as you note above and the light comes back on you know it is not the bag itself.
The connector to the airbag controller is very delicate.

• I would unlock it and unplug it with the battery disconnected and spray out the plug and socket to it with some spray electronic cleaner.
• The clock spring can be tested without removing it or the steering wheel. Just remove the steering column covers left & right and pull out its pigtail from the hole in the dash and unplug it to gain access to its connector, then loosen the star screws from the back of the steering wheel lift out and unplug the airbag and you will have access to all the connections on the other side of the clock spring to do continuity testing of the spring with an ohmmeter. Again do all this with your battery disconnected.
• If everything checks out I would reassemble things, clear the code and see if it comes back.

rwestervelt

I was able to test the clock spring without removing the airbag. Following pp000830's instructions to get to the under-dash pigtail, unplug the pigtail and test the resistance across the two sockets. It should be about 2.3 Ohms. Please note that as a safety feature, the two sockets short out when unplugged, so you will need to use a toothpick to eliminate the short prior to doing the resistance test.

If it turns out to be the clock spring, the repair is simple and the part cost is under $250.

07C4S

Thanks for the tips. Need to run by Harbor Freight to get some long torq keys and the electronics store for a 1/4 watt resistor in the 2.7-2.9 ohm range (assuming my forum search is correct). Everything looks pretty simple. Hopefully its just a connection or the clock spring gizmo.

pp000830

If you end up replacing the clock spring read the instructions to properly clock the steering wheel so the clockspring pins (Item 2 in the illustration below) that engage it to the steering wheel are not sheared off.
The instructions to do this are printed right on the part and are also in the shop manual.

Part of the instructions is to use the deadbolt like metal lock mechanism on the face of the spring housing to hold the spring in position when remounting the steering wheel.
I have found this lock mechanism (item 3 in the illustration below) to be problematic as it can come loose and its parts fall into the steering column.
As an alternative to using it, I removed the lock parts and just use some electrical tape with a long tape tail threaded through the steering wheel to lock the clock spring in position. Once the steering wheel is mounted, I pull the tape out by its tail releasing the spring. In this way the metal locking parts are no longer present to cause issues down the road.
Andy

07C4S

User @71-3.0-911 sent me a resistor and I was able to bypass the airbag. It seems like it may be the issue but I'm going to drive around for a while with just the resistor just to be sure.

I did measure the ohms at the airbag once it was out of the car and came up with 0.3. Is this definitive that the airbag is the problem?

I would like to verify/test the clock spring - but I can NOT get to the connector buried in the dash to disconnect it. It's either zip-tied or taped to something and I can't pull it out through the column. It appears others have had the problem also but no luck yet getting mine freed up. Worried about breaking something.

My airbag is the black 4 spoke. Are individual parts available? It looks like the actual airbag (vs. complete assembly w/ cover) has a 944.347.092.00 part number. The PET has 993 #s per color which are extremely expensive. The 944 # isn't showing up on the typical part sites. I'm guessing the other number 993 347 089 00 is the # for the bracket only as it doesn't match the PET 993 numbers. That # does pull up complete used airbags on eBay but that can't be trusted. Most obvious # so probably what the sellers enter in the auctions. Any idea where to find an airbag for a reasonable amount?



.

07C4S

Just an update - I've been running w/ the resistor for a couple weeks now and no more airbag light. I'd say this confirms fault 2 "Driver ignition circuit to + or 0 V" seems to be a failed airbag.

Been watching eBay and the forum classifieds for a replacement. Hopefully something pops up soon. (I'm curious if I hooked up the resistor and the airbag if the bag would actually work and defeat the warning light...but that's not a test I want to perform!)

Thanks for the help.

07C4S

Another couple weeks and yesterday the light came back on - throwing the same code. Double checked the resistor was still in place - it was.

Just ordered a clock spring! Very odd that the resistor fixed it before but I'm also experiencing multiple failures in my A/C which is probably just the way things are on this era of Porsche.

07C4S

The "3 Hour Zip-Tie"....if Porsche wouldn't have zip-tied the clock spring harness under the dash this would have been a 30 minute job. Instead it was a 3.5 hour job b/c the lower dash panel had to come off along with the radio and CCU. (Before dash removal I used my boroscope to get a clear view of the zip-tie but couldn't get any tool in there to snip it.)


Lower dash removed for access

The damn zip-tie!

Plenty of slack w/ zip-tie removed

New routing w/ lower dash re-installed

knorrena

I am having similar problems with my airbag light. The car in question is a 1995 c2 with the 1995 airbag module. It has 82,000kms (51,000miles).

I used this thread as a guide to solve the issue and felt it important to raise my cars issues under the same topic.

I used my durametric to clear the codes (these vary but always include drivers ignition code 2) and that worked for a day or 2. Now when I try to reset the airbag errors the airbag light goes off, for ~0.5 secs, turns back on and stays on.

I suspected my clocksprnig. I removed and tested it with the voltage bar disabled with the small zip tie. I got 1 ohm across each of the two pins horn and the the 2 pins on the airbag connectors. There are 5 of 6 conductors in the clockspring, could these be bad? THe horn works. I suspect my clockspring is good, although I did not clean and reseat all connections.

I get 2.2ohms across the airbag, so I think I can rule that out. If it was bad wouldnt it read inf resistance?

All thats left is the module, but my durametric has never had a problem communicating with it. So I am pretty sure its ok.

At this point I am pretty frustrated. I have been working on this car for 2 years fixing issues ranging from a nearly complete reseal and a host of other PMs. I dont have much enthusiasm left for fixing problems. I need some help.

Ralph3.

Just a question from a 964 owner.

Do 993's have issues with the clock circuit board?

I had seat belt / airbag light issues on my 964 which were cured when I had the clock repaired.

knorrena

So i changed out my clockspring with a new one and everything works like it should and the codes cleared fine. I dont get it. I metered that clockspring out and it tested ok. What the hell?

btw, i already checked the soldering in the clock. I did find any joints that looked like a cold solder, but heated them up to melting anyway.

knorrena

I am the thread killer. All beware...

07C4S

Several of my tests pointed to something other then the clockspring also....but it was the def the problem as I've had no issues since August of 2019. I would guess the clockspring is the problem 9 times out of 10 and much cheaper compared to airbag or module failures. (Always check battery voltage 1st.) Worthwhile gamble to take. If it wasn't for that damn ziptie it would have been much quicker replacement!

knorrena

Yeah I agree, but i got buffaloed by my clock spring testing out as working. I think its one of those PM items that you just replace as soon as your car starts exhibiting the persistant airbag light problem. Testing the clockspring wont suss it out as the problem.

I learned from your experience with the zip tie. I was reluctant to take apart the lower dash. I might have gotten lucky and was able to slip a long screw driver along the wiring harness and popped the zip tie.

I chatted with a Porsche Tech at my local dealership about the issue when I went to pick up my new airbag. He is their restoration speciailist and happened to have a newly restored 993 that he was rebuilding the foam on the hardback sport seats. Interestingly he had also just replaced the clockspring because of a persistant airbag light.