Help - strange wiring passenger occupancy sensor E46 320D

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  1. Help - strange wiring passenger occupancy sensor E46 320D 
    #1
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    tompparker's Car Details
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    Hi,

    The airbag light has been on constantly since getting the car, and now have to get it fixed as it is now the law in the UK for airbag systems to be working to pass the annual inspection (MOT).

    Have been scouring the web to find a solution, and options include getting a program to diagnose the code, installing a bypass plug to make the car believe the passenger seat is occupied (if appropriate) and resetting the light using said the program (if necessary).

    This in itself seems like it would be fairly straightforward if my car's wiring was the same as others, but it has obviously been changed in the past with some other kind of junction box and much severing and splicing of wires on both the driver and passenger side. Whatever the goal of this surgery/butchery was it didn't work as the light has been on unerringly for the past 65K miles.

    I really don't want to pay a garage £££ to read a code and for parts and labour just to get a light to go out if it is something I could solve (and the light can't just be disabled - it has to flash on when the car starts). But with the above bizarre wiring I really don't know what to do. My initial thought is to scan for the error code (having purchased the tool), put in a 'normal' occupancy sensor, wire it up correctly and see if it will reset.

    Please could anyone provide a wiring guide or any suggestions on how to approach this?

    Thanks!


    P.S. Photos are of passenger side. The plug at the end of the occupancy mat cable (blue & white wires) is hanging loose and there is no port in the yellow box for it. The yellow box also has a cable and plug hanging loose. Some of the wires from the box go to the seat belt tensioner while others go/come from the front passenger airbag itself...
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    #2
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    Driftworkz's Car Details
    Model of Car:
    325
    Year of Manufacture:
    2004
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    I think your on the right track but for someone to help you/we will need the fault codes

    i recently bought a cable form cableshack on e*** and am very happy with it. I would advise you to purchase one and clear errors then post them up here

    the fact the light is intermittently on & off tells me that everything is wired to the correct place but may have an intermittent high resistance

    your fault may have something to do with your photos or it may not

    people often cut off the plugs as in your photos as they are prone for bad connections, hard wiring them ie removing the connector solves this problem
     
     

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    #3
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    mi1ky's Car Details
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    Someones tried (poorly) to bypass it before. Is there a diode and a resistor there?

    The box is the interface box, this is part of the factory airbag system.

    I would buy a lead and diagnose it yourself. After fitting a bypass you need to clear it anyway.

    I would try return it to original by matching colors and rejoining first. Since the mats unplugged its safe to say you need a bypass. They may have damaged the interface box too.

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    #4
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    Driftworkz's Car Details
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    ive had a few of these come in with occupacy seat errors. Some times even the bypass /emulators don't work. Now i just pay a mobile bloke equipped with autologic this tool can switch off the occupancy sensor

    so you wont need a working occupancy sensor or a interface box or even an emulator
     
     

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    #5
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    edber's Car Details
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    The seat occupancy module box is missing from the seat.
    The joined wires looks as if they are going to the seat belt buckle tensioner pyrotechnic and have nothing
    to do with the seat occupancy system.
    The two connecters at the top of the second and last pictures will connect to the missing module box.
    http://www.ebay.com/itm/BMW-1994-200...-/230946185705 This is what you are missing.
     
     

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    #6
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    goldbcfc's Car Details
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    My last e46 had this issue i tried two different by passes and the light after being cleared on daignostic would always come back after in the end my driver seat was quite worn/ripped so i just got two used mint leather front seats for £150 fitted them light went out and sold the two seats i took out back on ebay for £150...winner

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    #7
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    tompparker's Car Details
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    Thanks for the replies. Ran a diagnostic in INPA and got the attached fault codes for the airbag (81 Fault Lamp (AWL); 80 Supply Voltage; 2 Ignition Circuit ZK1 / Belt Tensioner Driver). Cleared the codes (and some engine fault codes) and hey presto the light went out. Sceptically did a long journey and then a short journey expecting the light to reappear but it has stayed off!

    Did a read of the ABG module in NCSExpert and no reference to OC3 for the seat occupancy.

    Thanks again.
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