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BMW 320d e90/91 airbag fault 93B4 drivers airbag stage 2

Posted By wolf3199 Monday, May 27, 2013 5:58:44 PM
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wolf3199
 Posted Monday, May 27, 2013 5:58:44 PM
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Hi everyone

New to here and am here to try and get some clarity to my problem, I have a 2006 320d with the airbag fault 93B4 showing (LAUNCH DIAGUN) I have checked all wiring from the airbag ecu to the and including the clock spring each wire is giving an OHMS reading of around 1.4 , I also have fitted a donor airbag and still no luck Sad also have dissconnected and cleaned the plugs underneath the seats ,, has anyone came across this problem, car is one owner from new and never been damaged altho last year the light came on after the driver hit a rut on the road and a BMW dealer re set the light and she thinks she hit a pothole about a week later and never bothered about it until now as it is due an MOT

Any help is greatly appreciated
RichTT
 Posted Monday, May 27, 2013 6:09:17 PM
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So just to be clear, you have a fault for drivers airbag so you mess with wiring totally unrelated under the seat?

Which airbag have you donored and how have you checked clock spring?
wolf3199
 Posted Monday, May 27, 2013 6:29:52 PM
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hi

I checked the plugs under the seat because if you google bmw airbag faults it refers to a lot of problems from bad connections under the seats so i just tried it w00t I checked across the clock spring for continuity and ohms is this correct? Oh and i donored the drivers airbag
Monday, May 27, 2013 6:45:03 PM by wolf3199
miketribe
 Posted Tuesday, May 28, 2013 2:34:24 AM
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Wolf,

I checked across the clock spring for continuity and ohms is this correct?

each wire is giving an OHMS reading of around 1.4

I guess you have given yourself the answer then.

What do you think the resistance shoud be?

Mike


Being in business would be fine, if we didn't need customers.
wolf3199
 Posted Tuesday, May 28, 2013 7:08:30 AM
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Ok hold on I am testing the loom from the airbag ecu up to the drivers airbag with both units dissconnected!! Google was a nosey too see was the fault common with BMW!!

The resistance measurements were taken on the loom from the ecu up to the clock spring and then accross the clock spring this is where I am getting 1.4 ohm on each of the four wires from ecu to airbag , I know the 1st and 2nd stage igniters are in the airbag so the customer got a second hand airbag and i fitted it but same fault is there. What should the resistance readings be?
xBenn
 Posted Tuesday, May 28, 2013 7:08:42 AM
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When testing the clockspring you need to have it disconnected completely from the airbag circuit The small current from a multi-meter used to test ohms can set off the air bag.

All you are testing the clock spring for in the most basic sense is to make sure you have a connection from the input side of the clockspring to the output side going to the airbag. So you should be testing the clockspring on it's own as a single component. Basically, you want to check there is continuity across the clock spring.

1.4 OHMS is not right - i'm not quite sure how or where you measured to get that reading.. but IF you have tested it correctly and you are sure you are reading 1.4OHMS then the clock spring is faulty...

If you don't know how to test it, please leave alone - if you are still planning on testing it, make sure it is isolated from the airbag (as there is nothing dangerous within the clock spring it'self)

Also if you have a multi-function steering wheel fitted - that also passes through the clockspring
xBenn
 Posted Tuesday, May 28, 2013 7:12:37 AM
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You need to start by testing the clock spring on it's own!

Isolate the clock spring from the circuit and test from the input plug to the output plug on the clock spring - if you suspect the clock spring is faulty, testing from the ECU will not help you test the clock spring

- Also bare in mind, I am not suggesting the clock spring IS faulty, only how you can test it safely -
Tuesday, May 28, 2013 7:15:17 AM by xBenn
wolf3199
 Posted Tuesday, May 28, 2013 7:19:47 AM
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Hi

I have tested the clockspring for continuity across all the 6 pins and all ok ( i know that the multifunction wheel eses this also) ill check my resistance across these again? I am also very aware of the dangers of airbags even though it does not read like that Smile can you explain what my resistance should be/
K And R
 Posted Tuesday, May 28, 2013 8:35:14 AM
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Wolf.

" I am also very aware of the dangers of airbags even though it does not read like that Smile can you explain what my resistance should be"

You are right it certainly does not read so, and asking about what the resistance across the clockspring should be, does not inspire any confidence.

I hope your customer is not paying for your learning curve.

Kev.



"If you dont KNOW how it works, don,t try to test or fix it"
Tuesday, May 28, 2013 8:37:27 AM by K And R
xBenn
 Posted Tuesday, May 28, 2013 8:35:17 AM
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Still assuming its the clock spring??

Think you need to start at the beginning... since although you say you are aware of the dangers im not so sure.

Have you checked live data to see what resistance the ECU is seeing on the STAGE 2 ignitor? don't know why you checked under-seat connectors. Do you know what a 2 stage air bag is?

Start by telling us what the data is telling you for the stage 2 ignitor?

If it's a fault with the airbag it'self, do you have resistors to be able to emulate the correct resistance of the airbag?


IF/When you've re-tested the clock spring post results on here - Also remember some clockspring faults are only present when the steering wheel is moved so test it with the clockspring reel in various positions?


Post this information and tell us what you think is incorrect/stands out..??
Tuesday, May 28, 2013 8:37:02 AM by xBenn

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