Hi all,
A couple weeks ago I drove over a speed bump while turning and I received the "Pass. Restraint System" fault on the iDrive screen, accompanied by the seat belt and airbag lights on the dash. Scanning with the Carly adapter showed 93B4, or "Driver Side Stage 2 airbag". Uh oh, that sounds serious! After resetting the error, it came on about a mile later when I hit another bump in the road. This time, I received 93A8 fault, which Carly misdiagnosed as "Central control timeout" but google reveals to be "Driver Side Stage 1 airbag."
Basically, these errors mean that the airbag ECU is not seeing both of the airbag's 2.2Ohm resistances that it should. The driver's side airbag, located in the steering wheel (the one we all got recall notices about) has two stages, each with its own connector and 2.2Ohm resistor. If the airbag ECU doesn't see the 2.2Ohm resistance, a fault is thrown.
To confirm the problem:
1. STORE YOUR PRESETS and disconnect the battery.
2. Remove the driver's side airbag by inserting a screwdriver through the tiny slots in the leather. Check this video for hints:
https://www.youtube.com/watch?v=7iZG8Y0Wm6Q
3. Disconnect the two airbag connectors. Again, make sure your battery is disconnected first. To separate the connectors, pry the thin clip away from the airbag with a flat blade screwdriver.
4. Disconnect the left connector leading into the clock spring. These are the airbag wires.
5. Pins are 1-6 from left to right. Check resistance of pins 1&2 and 3&4. Both pairs should be ~7.3kOhms. If they are not, congrats! You have a damaged clock spring or wire harness leading into the airbag ECU.
At this point, I wanted to see if I could repair my clock spring rather than buying a replacement. ($50 is a lot!) Following advice on the web, I removed the clock spring by first removing the steering wheel, then the upper and lower cowls around the steering column. More detailed instructions here:
My $0.02 Steering Angle Sensor Fix
After opening the cover of the clock spring, I discovered the problem: there was a "kink" in the ribbon cable which was causing intermittent contact. I did successfully solder the cable back together, but I have no hope as a long-term repair so I did order a replacement from eBay.
When reassembling, make sure you follow BOTH index marks (one on the steering wheel, the other on the steering angle sensor). Failing to misalign the steering angle sensor will cause a 4x4 error light after you reach 20mph. See more details here, pic 7 and 10:
My $0.02 Steering Angle Sensor Fix