Thaddeus

Hi,

I earlier posted a question on erasing an error code on an OBD1 car (1995). Here's why.

Earlier today I was tooling around and my Porsche stereo cut out (no power). I checked the fuse box and the fuse was loose and wiggly. So I replaced it (old 928 trick: even if a fuse seems fine, replacing them sometimes exorcises gremlins) . Then I checked all my other fuses too, found some other wiggly ones, and replaced those.

When I restarted the car, the stereo was fine, but I had no gauges. Loose fuse... so I turned off the car, redid it, restarted the car, and the gauges worked. HOWEVER: the air bag warning light came on, going off after 2 minutes. It does this repeatedly.

Adrian Streather's book says that an air bag light that goes off after 2 minutes indicates a non-critical fault-- one that does not compromise the function of the air bag. (I timed the interval: 1 minute 58 seconds).

I then did the trick where you can read the faults by turning the key to the "On" position and depressing the pedal. The system came back with the no-fault code. Adrian's book also says an air bag fault code will persist until it is cleared. I tried unhooking the battery, but the air bag light still comes on for ~2 minutes.

My hypothesis is that the bad power to the gauges (or the other fuses I pulled and reinstalled) caused the air bag system to throw a fault, which the system recognizes as non-critical, but which I cannot now clear. In other words, there was a momentary fault, now corrected, but thhe code is persisting. OR, I genuinely have a problem (heavens forfend).

What do people think? Anybody experience this before? I am thinking, since the code-check trick comes back empty, that the air bag system has its own code storage system that I'm not accessing with the flashing light trick.

How do I access the bad code, or clear it? Is there a Porsche dealership in my future? I plan to drive it (cautiously, assuming for safety's sake I have no bag), since the bag should still function, but I would feel a lot better if the light wasn't coming on at all.

Thanks.

cabrio993

The ODB scanner won't remove the airbad check light, only the hammer tool can reset that light.

Stealer charged me $50 to reset mine after I changed my steering wheel without disconnecting the battery first.

Thaddeus

A-ha! So there was not a true fault with your car, just a persistent code that could not be cleared, caused by a power thing, eh?

Thanks. That's a useful tidbit, that.

cabrio993

Correct, once the air bag light triggers, the flag is set on the airbag control unit and the only way to reset it AFAIK is with the PST or Hammer tool. The ODB reader can only reset the Check Engine Light.

brucec59

My light stays on all the time. It was on when I got the car, and the shop that did the PPI ceared it without charging separately for that. It came on again a few weeks later. The next time I take it in for service, I'm gonna ask them to clear it again. From reading rennlist, it seems that the airbag system is fine and will work in a crash, but the fault code causes the light to trip.

JasonAndreas

Do you know what fault code is stored in the control unit?

If the airbag warning light is illuminated ALL the time that means the fault is "crash-relevant" and the airbags will not deploy in an accident. Only if the light goes out with 2 minutes does it mean that the warning is "non-crash relevant" and that the system is not disabled. Depending on the version of software running in the airbag control unit the only fault code that presents as "non-crash relevant" is Code 19, Airbag warning light leakage resistance / short to positive or open circuit or Codes 0 & 1, Warning light Airbag (same problem different code numbers).

xrix

Mine is on all the time. I got it on a diagnostic (iScan) and couldn't even connect to the airbag unit. Since then I've replaced the control unit and now the scanner says that I have power supply failure to igniter 1 & 2. Sound definitely crash relevant :-/

Anyone know what's best to check next?