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Old 06-14-2010, 02:17 PM   #1
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Join Date: Feb 2010
Location: UK
Posts: 590
My Ride: 325ci 2001
Exclamation Airbag Occupancy Sensor Bypass Unit DIY (pics)

Well, every time I had a passenger in my car I got the really annoying airbag light on my dash. This is due to the sensors in the passenger seat failing or having failed. The seat has a mat inside it that can detect the presence of a person. Now this has broken the ECU detects that and puts the airbag light on. The bypass units can be bought on ebay very cheaply, mine was 5 delivered. They are basically just a small resistor to imitate the resistance created when a passenger sits in the seat. They are used to control the deployment of the passenger airbags. A crash with no passenger means no passenger airbags deployed saving on repair costs. Now this unit is fitted the airbags will always deploy as it always thinks there is a passenger (better than the other way round). The only downside is now you can't put a baby seat up front due to the airbag deployment. This, however, wasn't an issue for me and is way better than the 480 BMW wanted to fix it.

Any way, on with the DIY!

You will need:

Airbag occupancy sensor bypass unit
Maybe some tape/zip ties

Okay first up you need to roll the seat forward as far as possible then tilt it forward as much as you can. You don't need to go mad and push it forward there should be enough room if you lay down on the back seats. In this picture my fingers are on the connector unit that you will be working on:

If you look under the seat its right on the back side closest to you, ignore all the cables in the middle underneath. This is the unit you need to find:

At the top of the image above are a blue and white wire. These wires come out of the box (left side as you look at the image) and in to a connector block. The right side of the connector block needs to be unclipped and pull as much slack as you can out. This is the connector hanging down here, excuse the really bad photo:

Here is the connector cut off, leave yourself a couple of inch of wire on it:

Here is the bypass unit I will be connecting:

Mine came with some crimping blocks that needed to simply have each wire inserted and crimped shut. You may need to strip and twist them together then insulate with tape. Either way is fine and should look like this:

Now simply plug the connector back in to the unit and zip tie or tape the wires out of the way. Enjoy no more airbag lights!!

Last edited by Scott87; 06-14-2010 at 02:19 PM. Reason: Image Link
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