04-14-2008, 11:23 PM
Join Date: Dec 1969
My Ride: 03 Ti Silver M3
Fixing the airbag light - seat belt pretensioner error code
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 **
1) This is what I started with
2) Here is my brand new Peake tool from BimmerTools.com
3) Plug in the Peake too to the OBD port that is in the drivers side foot well. This should be attached to the underside kick plastic....but mine isn't...yeah.
4) Read your codes following the directions that came with the tool, very simple.
5) My code was table 10, code 02 which is drivers side pre-tensioner.
6) Start by disconnecting the battery.
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).
8) Unbolt the rear two seat bolts.
9) Remove the plastic caps covering the front seat nuts.
10) Remove the front seat bolts.
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.
12) Remove the wiring harness from the pre-tensioner.
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.
15) Remove the black shield part of the connection. You need to pull back the clips on both sides. The clip is just at the tip of my thumb.
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.
17) Plug the yellow connectors together reconnecting the pre-tensioner to the car. I rigged it up so I could plug in the seat while it was sitting outside next to the door.
18) Reconnect the battery, reconnect the Peake tool, clear the codes and cross your fingers!
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!
My E46 M3 Rebuild Thread
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