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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 01-07-2011, 06:31 PM   #41
bw46508
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you need a special diagnostic computer - cant really use anything else.
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Old 01-07-2011, 06:32 PM   #42
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haha! yes, you were doing it and re-doing for nothing man!!!
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Old 03-21-2011, 09:07 AM   #43
Andrews2nd3
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Plug Housing

Thanks for the DIY, and to those who posted how to DIY a bypass.

I just made my own bypass this weekend using the 2/ 100 ohm resistors and 1N4001 diode. I wanted to post up the part numbers for the actual plug and wire leads...I had to dig for awhile to figure out the part number, so I thought this would be helpful for somebody else. I did not want to chop the plug off my sensor mat (yeah, I know it is broken anyway...but...whatever).

Plug part number: 61138365340 (this is just the plug housing, you will need the two wires with the pins as well - listed below)

Wire #1 part number: 61130005199
Wire #2 part number: 61130006665


ECS had all 3 of these in stock. Good luck, happy bypassing.
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Old 01-14-2012, 12:16 PM   #44
mattnourse
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Reverse Occupancy sensor

Quote:
Originally Posted by profor View Post
if somebody is little bit more skilled, he can do it himself and not buying things from eBay.

I did some research by measuring the ocupancy sensor which was okay, and figured out which components You need to bypass the sensor if it is broken.

So You need soldering iron, not shaking hands and one 3k3 to 30k resistor and diode 1N4007.

schematic diagram is in the picture



CAUTION:

this is modded bypass modul that was previously posted on some forums, but that "OLD" one caused the airbag light off but the seat was in control unit of airbags NOT OCCUPIED. therefere I did this mod which will make the seat "OCCUPIED" even if nobody is there!!!!!

Hey buddy,

I want to turn the airbags off as i want to put my child in the front (he is a nightmare to keep entertained) Im thinking, if we can trick the occupancy sensor to say the is always a passenger, we can also trick it to say there isnt one.

Does anybody know the resistance of the sensor if no one sits in the seat?

Then i make a resistor up for that and off we drive.

Kind regards

Matt
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Old 01-28-2012, 01:33 AM   #45
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the pad's resistance should be between 9- 10M Ohm with no occupant and when someone sits on it, it should drop to under 100 Ohm. That is the way the sensor can sense whether someone is actually sitting or not.

make the same thing to read between 9-10mega ohms
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Old 01-28-2012, 04:43 AM   #46
RKiepper
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I need to check mine out tomarow as simply re-setting my system didn't work. I though it was a simple pressure switch... Not so simple.

Last edited by RKiepper; 01-28-2012 at 04:47 AM.
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Old 01-28-2012, 06:54 PM   #47
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what is the tolerance of the 4.7 k resistor hes using....it looks like its brown at 1% 5th color? i dont think it matters though....im guessing this to be a standard ¼ watt resistor

the other set up uses 2 100ohm resistors (un occupied passenger) bag wont go off

this one uses 3300 3k3 to 4700 4k7 ohms....and hes using a 47000ohm resistor which is 47k (bag will go off whether there is passenger or not) why the dramatic jump in resistance from 3k3 to 47k i dont know

for those of you that dont know the k in the middle represents a decimal place. they use it for schematics to not make a mistake as decimal symbols are small.

the stripes represent values (ex...{yellow is 4) {purple is 7} and orange represents three zeros behind it meaning 47000)and can be checked by using a resistor color coder easily found online the first 3 stripes are the most important. the 4th one represents a + or - or tolerance and the 5th is just a quality standard and is sometimes not there

i just got a message from andrews2nd3....

"Hey man - I actually used a 1/2 watt, 5% tolerance resistor - radio shack part # 271-1130" read his post below....with the resistor part # and the diode you have all the exact info you need to do this job. You will have to use an srs code reader to turn it off. peake research sells them. but the better diagnostic equipments does alsom...like autoenginuity

Last edited by glhx; 02-02-2012 at 05:48 AM.
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Old 01-31-2012, 03:23 PM   #48
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The method proposed by profor will put the seat into an ‘occupied’ status, so the airbag will go off in the event of a crash. The method with the 2 100ohm resistors puts it into an unoccupied status.

Yesterday I had my car at the indy for an unrelated issue and I asked him to check on the computer whether or not the seat was coming up as occupied. I had the 2 100 ohm resistor bypass in place and the seat came up as ‘unoccupied’. I changed it last night to the profor's version (although I used a 47k resistor and a 1n4001 diode), and it was showing as ‘occupied’.

So, if you want your airbags to go off, you should use the 47k resistor and diode combo that profor explained.

Disclaimer: I’m not liable for anything you do or any damages you incur on yourself, your car, or other people….
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Old 02-01-2012, 06:49 AM   #49
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thats good to know. i thought they both made the seat occupied.

Last edited by glhx; 02-01-2012 at 07:23 AM.
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Old 02-02-2012, 09:23 PM   #50
haurelio
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I have been in the forums for a while now. what profor proposed which I did, fools the computer as if the seat were occupied. the airbag "should" deploy in case of an accident.
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Old 02-03-2012, 02:40 AM   #51
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I had the exact same problem in my coupe... You can buy one of the bypass units from ebay or... go to a repair shop and they can "set" the occupy sensor to always on. It was free for me since i knew the guy but this way i didn't have to replace anything and the seat sensor is always on. Also, the seat sensor is around 30lbs of a trigger, so any child of a decent size would trigger it. Plus anything smaller than that should never be in the front seat as is.
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Old 02-26-2012, 07:58 AM   #52
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the soldering process for this (for someone whose never done it before)

plenty of light and you could use a magnifying glass like is used for model cars but you really dont need it
rosin core solder
flux paste
25amp soldering iron
will post the radio shack part numbers for the resistors i used later

the solder tip i used was flat like hammered metal. It was in the shape of a spade. you really want to use something thin and pointed. like fender washer thin or thinner

the larger typical round tips will not work. The pointed tip cant hold enough heat to melt the solder. The smaller the tip the better

what i did: i cut the wires near the white plastic connection that goes to the circuit board,...you will see what im talking about because in the pictures it is already removed

then...instead of ripping the white connection out, I slowly broke the white housing. this left me with the 2 crimped connectors still connected to the board and i soldered to those.

the project was successful....you do not have to take the seat out. Tilt the seat forward and then lift it. The sensor is closer to the back part of the seat than it is to the front. When you lift it up its right there. easy to see and very easy to get out. there is nothing in the way and nothing covering it.

after this was done i used my bmw scanner 1.4.0 to turn off the air bag light (you have to turn it off, it wont go off after it is fixed). It costs $68 shipped but ive seen it for $30. Most Bmw owners probably wont need anything else but this software for anything they need and some things they dont need. Dont bother with the dealer or indy shops for this. Just buy the software and dont get one of those peak airbag devices. it costs 3 times more and the software listed above will do close to what a gt1 will do.

Last edited by glhx; 02-26-2012 at 08:03 AM.
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Old 03-12-2012, 12:28 PM   #53
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Quote:
Originally Posted by bw46508 View Post
Not sure which resistor to use - 3.3K, 4.7K or 47K as all three of these have been mentioned in the previous posts. Will all 3 make the status of the passenger seat 'OCCUPIED'
Any ideas?
Quote:
Originally Posted by bw46508 View Post
The light will defo go out with the old circuit i.e. 2 100ohm resistors in series with the diode. However, I dont think this makes the seat 'OCCUPIED' and that is what I am trying to resolve.
Floorjacker - you say that you have tried them all but did you reset the codes man?
Hi, I'm a seller of these on eBay and I see you are actually a seller on eBay of these items as your username is the same as this previous name and is also from Preston. You have used 2 accounts and here are the links below with snapshots also. It's obviously you due to the randomness of your username and coming from the same location

http://contact.ebay.co.uk/ws/eBayISA...=airbagmodules



http://contact.ebay.co.uk/ws/eBayISA...quested=a3_thr




This is a picture of one of your items that someone recently bought from you so can I ask why you don't clearly state that airbag WON'T deploy seeing as it's not even got any resistance in it?




here is a link to a more informative post about this on a 5 Series forum as this is where I got your item from

http://forum.bmw5.co.uk/topic/64274-...ost__p__674393


Strangely you did ask people if they were Are you concerned that your airbags may not deploy in the event of an accident? as shown in blue text in this item below. Whereas in your current listings you've now removed that question for obvious reasons

http://www.ebay.co.uk/itm/190637462530

I know you've got a disclaimer but surely you know it WILL NEVER deploy (you've got a typo for deploy by the way). Therefore don't you think that your buyers should be made aware of this seeing as most will have passengers?

Quote:
What are the cons to bypassing the occupancy sensor?

Whilst the bypass unit will reactivate the airbag system (if it's even disabled in the first place), there can be no guarantees that the passenger airbag will depoly in an accident. We have spoken to different BMW Technicians and there is different opinion regarding this. The buyer would be accepting this by clicking on 'buy now' button. It must always be remembered though that this is only a short term 'workaround' and not a long term fix.
I hope making you aware that quite a few people are now know what you are selling will possibly make you change your ways

Cheers

Mac

Last edited by MackemX; 03-15-2012 at 01:32 PM.
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Old 03-20-2012, 02:36 AM   #54
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Quote:
Originally Posted by profor View Post
Todays mod - used 4k7 resistor




Thanks profor! To confirm, the above works perfectly using 1N4007 + 4k7 resistor as described.

And I recommend doing it this way as it's very easy to do, much cleaner and you definitely know the airbags will go off. Although being an engineer helps my motivation to mess around with electrics and why I love these cars.

I've added a few more pics if you guys want to see how I pulled it off, and opened it up. You can't really break anything (famous last words), but really, it does come off quite easily like most things BMW


When you've unhooked the cylindrical connector which is connected to the seat pad (top right of pic), you can twist the enclosure and it will pop off from under the seat. Then you can unhook the white connector. I used a small flat head to help nudge the locking off. Once this is off, you can use the same small flathead and just slot it in the end where the arrows pointing and draw it around and the enclosure will pop open and you can slide it out.



I cut the wires off, then just de-soldered the header (where the connector inserts into the board) off. Then just follow what profor has done - solder in the diode and resistor (check polarity of the diode is correct). Only thing I added was just a small precaution and that was to insulate this with a bit of tape or heat-shrink before closing back up.

And now I don't have any more issues with intermittent airbag lights when people sit in the passenger seat, nor worried it won't go off should it have too.
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Old 04-15-2012, 02:40 PM   #55
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I had the airbag red light on.
I used this mod:
Now the light is off.
Can someone confirm that with this setup the airbag WILL NOT DEPLOY in a car accident and that the profs way WILL DEPLOY?

I want to combine the two methods and have a button to switch them.
Will the schematic below work?
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Old 06-12-2012, 08:23 AM   #56
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this is a very informative thread. my airbag light comes on whenever anyone is sitting in the passenger seat. I will be definitely giving the bypass method a go, although i have a quick n00bus question... how do i know if it the sensor or the actual mat that is faulty? is there a chance that by installing the bypass the airbag won't deploy? the codes which came up were;



please let me know what i need to do. i HATE driving with someone in the passenger seat knowing that the airbag won't deploy.
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Old 06-12-2012, 08:38 AM   #57
mexus
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The mat is broken.... You need to install the bypass - the one with a diode and resistor in parallel, or my mod witch has airbag on-off switch...
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Old 06-12-2012, 07:23 PM   #58
glhx
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We dont know for sure.....The occupancy sensor breaks so much that you are 90% sure thats the cause....and your diagnostic shows that this is probably the case.

On another note.....i used this resistor and recently ive had a problem saying resistance is too high. I turned it off and 3 weeks later it came back and would not turn off. I unplugged it and plugged it back in 2 or 3 times and it was fine...so far
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Old 06-12-2012, 07:45 PM   #59
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Quote:
Originally Posted by mexus View Post
The mat is broken.... You need to install the bypass - the one with a diode and resistor in parallel, or my mod witch has airbag on-off switch...
Quote:
Originally Posted by glhx View Post
We dont know for sure.....The occupancy sensor breaks so much that you are 90% sure thats the cause....and your diagnostic shows that this is probably the case.

On another note.....i used this resistor and recently ive had a problem saying resistance is too high. I turned it off and 3 weeks later it came back and would not turn off. I unplugged it and plugged it back in 2 or 3 times and it was fine...so far
I appreciate your help guys.

Ok so i roughly know what this 'bypass' module is all about... but i'm not going to lie, i have absolutely no idea what resistor and diode means etc etc....

So is the mat itself broken or is it the sensor? If i install the bypass will the airbag still deploy?
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Old 06-13-2012, 07:16 PM   #60
mexus
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If you get the error probably the mat is broken (the mat is the sensor). There are two types of bypass, one simulates occupied seat, and the other empty seat (I first case the airbag will deploy in the second it won't). I combined the two versions, so I have a manual switch and I can choose empty or occupied seat.
Sorry for my English...
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