jmrjames

Meaning of Airbag Malfunction 1991 S4 ???


What are the implications of the Airbag Malfunction warning light remaining on in a 1991 928 S4 ???

What are the costs to repair associated with each problem ?

Thanks in advance for any input.

John Speake

Probably means you will fail any vehicle inspection that you have to pass. Airbag fault codes clearly are classed as "safety critical".

You can only cancel the light with a diagnostic tool. The tool will also tell you what is the prblem with the system.

JPTL

You have two choices:
Determine the cause of the fault by getting a fault code readout to define the problem.
The necessary daig. tool is a DT999 (Theo's tool) a Bosch Hammer or a Baum with the proper software. I believe there are a few others out there, but shops with any of these tools are few and far between. The code will identify the component that's causing the fault. It is capable of resetting the code, but the fault will likely reappear, because a reset isn't a fix. So you'd get the reading, make the necessary repair, then go back for a clear of the code.
There's specific behavior that can identify specific culprits as an educated guess prior to a diagnostic read, such as which warning lights go on; which can be turned off & which stay on (if any). I'm not sure which tell what, but I believe that Alan or Dave Roberts knows the symptoms from experience.

Your second choice:
Clean the contact to the passenger side sensor.
Over the years, I've followed the post-'90 airbag faults and the causes. Going back 10 years to Ed Ruiz' '90 GT throwing the fault, to my GT throwing it a year later. In both cases, it turned out to be the passenger side sensor (low resistance).
Since then, the overwhelming majority has been the passenger side sensor as the culprit...2-1 from what I've seen. Others w/experience may want to chime in (Ed, Doc Mirror?).
Of course replacing this sensor is almost definitely a cure for this fault. But from what I've seen (including my experience) the preferred cure to the pass. sensor throwing the code has been a cleaning of the sensor connector. Threads on this subject in a somewhat relative order:
https://rennlist.com/forums/928-foru...ere-is-it.html
https://rennlist.com/forums/928-foru...i-test-it.html
https://rennlist.com/forums/928-foru...or-update.html

928 at last

Clean the contact to the passenger side sensor.
+1
DeOxit is your friend.
Mine "Looked" new on disassembly. Cleaned and reassembled...end of problem.

hacker-pschorr

Most common failure for an airbag system is the metal contact ring in the steering column.

RyanPerrella

did you remove the steering wheel and airbag while the battery was still connected, or while the chassis had power? This would trigger the airbag malfunction light.

If thats the case then you need to reset the airbag sensor.

Greg Brown did this for me, in the end the light was triggered because i pulled the steering wheel off while the battery was disconnected. Also note that if the car battery is connected at anytime while the steering wheel if off and the airbag disconnected it will trip this fault and it will be stored in memory until you delete the code. So if your airbag wheel is coming off...... KEEP THE BATTERY DISCONNECTED. Or if you can reset airbag lights then dont worry about it.

John Speake, can your diagnostic tool or perhaps the sharktuner MKII reset airbag lamps?

Can Theo's diagnostic tool do this?

Last I heard (now maybe i read too much into this) was that the Sharktuner can also perform as somewhat of a DELUXE diagnostic tool and can reset and test many functions of the car. Is this true? Would having a sharktuner MKII make the earlier diagnostic tools unnecessary?

John Speake

Hi Ryan
Neither the "Spanner" nor the SharkTuner can delete an airbag fault code.

It is true that the Sharktuner can act as a real time diagnostic tool for virtually any LH or EZK function, beterr than any diagnostic tool, but it does not "talk" to any of the other ECUs in a 928.

RyanPerrella

ok so the spanner and hammer would still be necessary to talk to other systems in the car. Such as to test the ABS or PSD or other such things?

But for all engine diagnostic the ST would be the first choice. Gotcha