Recently my airbag light randomly came on. After searching around on the site I realized the only way to accurately diagnose the issue is with a airbag code reader/reset tool. Ken at www.Bimmertools.com hooked me up and in a few days I had a shiny new tool.
Here is how I fixed the common seat belt pretensioner issue. My searching turned up an interesting issue. Often times the pretensioner itself isn’t bad, just the wiring. I was hoping this was the case because the wiring is much cheaper than the pretensioner. I had a spare wiring harness handy. If you don’t (why would you) I would suggest ordering one (approximately $15) and trying this before you invest in a new pre-tensioner.
** Use this at your own risk **
5) My code was table 10, code 02 which is drivers side pre-tensioner.
7) Disconnect the under seat connector freeing the seat from the wiring harness. You can pop the connector open by using a screwdriver to move the slider/lock over towards the centerline of the car. You can see the lock is moved over a finger width in the first picture. In the second picture you can see the lock all the way out (next to my thumb).
11) Remove the seat headrest, tilt the steering wheel up and push it all the way in. Lift the seat up and rotate it around and sneak it out the door. If you have a sedan you can leave the seat belt attached to the seat. I set the seat just outside the door.
13) Remove the wiring harness plug from under the seat by pressing the two clips on either side to release it, the slide it back. Look at the second picture to understand what you’re trying to unclip.
14) Cut the one zip tie that holds the wires and undo the other wire holding clip.
16) Take your new wiring harness and connect it to the pre-tensioner. Don’t worry about routing the wires under the seat yet. We want to test the new wiring harness before we bolt everything back together.
20) If you’re airbag light is still on disconnect the battery and recheck all your connections, try reseating all the connectors, plugs, etc and test again. If your airbag light is still on then you’re going to need to order the pre-tensioner. Bolt everything back together for now until you get the new parts.
21) Assuming the lights off it’s now time to put everything back together.
22) Disconnect the battery and then disconnect the seat wiring.
23) Route the wiring on the seat back in the correctly (reverse of how you took everything apart), mount the yellow plug back under the seat and you’re ready to mount the seat again.
24) Put the seat back in, bolt it down, reconnect the wiring, reconnect the battery, etc.
25) Done and done, congratulations!
Writeup by: tim330i