mferris

1995 993 C2 Cabrio, 6 month old battery, other than the Airbag codes below - I only have one other warning light - the cabrio top light does not think it's up b/c I am in the middle of fixing a twisted top. Otherwise the car is perfect.

I replaced the CR-210 head unit with a new Blaupunkt Frankfurt this weekend. I have the HiFi with (i presume) the original amp under the passenger seat.

After driving for 15 minutes - the airbag light came on. Now, when I start the car, it comes on, blinks once, and stays on.

My Durametric has some trouble communicating at times with the airbag unit, but with enough tries I'm able to read the codes and reset. But the light still comes on after driving.

However, the codes have changed one day to the next. (yesterday was passenger seat occupancy sensor, today that is gone (after resetting) and ignition circuit).

I have not tried to clean any connectors yet.

My concern is this is that this may be? the result of a voltage change after my radio install. The Frankfurt install was very, very straightforward - connected the original ISO plug with Power/etc direct to the unit and the lineouts direct to the plugs for the amp. The *only* wiring change I had to make was splice the powered antenna output and connect it to both antenna (like original) as well as the amp switched power line (to signal the amp to turn on).

Stereo works great (barring blown speakers - which are next).

Before I start taking things apart - any ideas about random codes and a stereo install?

Durametric logs attached - shorter one is from day 1 (when my wife was in the passenger seat), longer is from day 2 after I reset.

bobbyp

Is there actually a seat occupancy sensor on a 993?
Mine was throwing a driver side seatbelt sensor code on a Durametric, but there is no seatbelt sensor on a 993 (as I have been told).
Not sure that the Durametric translates codes 100% perfectly on a 993.

e9stibi

I do not know the Durametric Codes but my UDT 999 showed me Airbag Low Voltage as an Alarm on my convertible. A new battery cured the problem at least for know but there must be a voltage drop that the Airbag unit does not see more than ~10V which will throw the code.

Good luck finding the root cause!

mferris

Thanks. I have not noticed any voltage drop. I did *not* unplug the battery when I installed the stereo - perhaps I started something. But considering it seemed fine when I started it and then the code came up 10-20 minutes into a drive it seems odd.

Maybe resetting (which again is hit or miss with the Durametric) the codes will stop happening.

Had a similar problem on my 968 and a new airbag (not controller module) fixed that permanently.

pp000830

Hi MFerris,
Like you, I ran the OBD Codes with Durametric and returned lots of codes including the one for the airbag light and many, as you show above, that lack descriptions.
I pulled the wiring diagrams and it seems that the only components of the system are the two airbags, the controller, and the steering wheel pass-through contact unit. My 1996 has the earlier airbag controller used in the '95 cars. I guess the transition to the newer controller was a mid-model year change.


In any event, seeing that there are only 4 components in the system the easiest thing to do is get out an ohm meter and a can of spray electronic cleaner, detach the car's battery, and clean and test all the connectors on the airbags, the contact unit on the steering column and its plug and the clock plug and socket and the warning bulb mount contacts. I will clean the clock's contacts first as it is minimally invasive to do, then clear the codes and see if they return. Then I will clean the connector on the controller, which has a very delicate locking latch and plug, clear the codes, and see if they return, then if that doesn't clear the code,

I will pull the airbag module in the steering wheel and check the wire continuity to the airbag and contact units pigtail plug & socket just behind the dash along the right side of the steering column that can be pulled out and unplugged after removing the steering wheel column clamshell covers and cutting the tie-wrap that secures the pigtail.

My hunch is if it isn't the clock it is most likely the steering column contact unit as it is the only component subject to movement and therefore mechanical wear.

It's beginning to get into the hot season here in Dallas so I may not get to it for a while. I'll keep you posted on my outcomes.
Andy

bobbyp

Andy, thanks for confirming that the driver seat belt airbag warning is spurious and probably just due to Durametric's attempt to diagnose all Porsches from the 1990s through at least the 2010s.

pp000830

Hi Bobby P,
You are welcome.
Here is a page that touches on the 993 Airbag (SRS) system and how to service it:
https://993servicerepair.blogspot.co...ing-light.html
Andy

mferris

Ok - well - as an update, I reset the codes in the Durametric (or kept trying to reset until the light went off on the dash). Took the car for a 50 minute drive, used the A/C, Lights, (new) stereo and the Airbag light did not come on.

I can only presume that when installing the stereo head unit the voltage during the install got low enough somehow and triggered some codes and 2 resets later it doesn't come back. But I've been here before in my 968. Will see how this resolves.

Off to the convertible top shop tomorrow to see if they can help me with my twisted top.