87 951 airbag light on

[RichMason]

I'm buying an 87 951 this week. The car has a few minor problems including an airbag fault indicated by the airbag light. The previous owner said that Porsche quoted him $1500 to fix, which included new airbags. The car has not been wrecked and the bags have not deployed. Any suggestions on how I could fix it? If not fix, how about disabling the system so the light will go out? I need to disable the passenger side anyway for a car seat.

[WinfieldKS]

The air bag lamp will come on for any fault whatsoever in the system. Given that the air bags have not been blown I'm going to assume that the two air bags themselves are okay and also that the control module and the sensors are okay.

That leaves two possiblities. One is that there could be a wiring problem of some sort which could be anything from something unplugged to corrosion in a connection. While possible, a wiring problem is somewhat unlikely.

The final possiblity then is that the steering wheel was removed for some reason and then reinstalled improperly, causing the clock spring assembly underneath the steering wheel to become damaged. The most likely cause is that the person installing the steering wheel did not (A) wind the clock spring 4 1/2 turns back from the stop at either end of the travel &/or (B) failed to align the plastic boss of the clock spring assy (where the wires come out) with the matching elongated hole in the steering wheel hub. If the plastic boss doesn't line up with the hole then there is no clearance for the boss and the clock spring assy will become mashed & damaged when the steering wheel is tightened down. That's all it would take to defeat the system and light the warning lamp.

BTW, don't ask how I came to know this.

I am not sure that there is a way to disengage just the dash air bag. If you simply unhook it then the entire system would likely shut down. I doubt that you'd find any commercial mechanic willing to take the liability in trying to modify the system away from the OEM design.

Good luck,
Greg Laws

[RichMason]

Greg,

If I wanted to check these items, how would I safely remove the steering wheel?

[WinfieldKS]

1. Disconnect the battery. Wait 5 minutes.

2. Using a T-30 six-point male socket, unscrew the two capscrews that hold the air bag on. They are on the back side of the steering wheel spokes.

3. Remove the air bag. Handle carefully and store it safely with the metal side down.

4. Remove the nut holding the steering wheel on. I've forgotten what size it is but it's pretty big. I remember that there's an SAE size that's close enough to work.

5. Mark the shaft and the wheel hub so that you can reinstall at the same alignment later. A dab of touchup paint works well...

6. There's probably a tool but I just grab the wheel and wiggle/pull until it comes off.


Greg Laws

[IceShark]

You can also trigger the airbag light by just disconnecting the battery under certain conditions. There is a 3 post female white Molex connector that goes nowhere behind the glove box up the firewall. That is the ticket to resetting by grounding out the center connector in a sequence of 5 second intervals. Clark's Garage has the procedure layed out.

Disconnecting the passenger airbag is a little trickier. You need to do a bypass ... there is a current thread on Rennlist right now that lays out some options.