L322 Airbag light 0x50 Supply Voltage Less than 9.6v

According to my RAVE (which only covers 2003) it's like this. Fuse 44 feeds C0256 Pin 5.

Could be worth pulling the fuse to force a fault and see if the GAP IID sees it. Or remove the resistor and see if it sees that.

That seems a good test fir Tommorow.

In good news the replacement positive battery lead advised today too.

backinblack said:

Could be worth pulling the fuse to force a fault and see if the GAP IID sees it. Or remove the resistor and see if it sees that.

Click to expand...

I am still batteling with this,

I have replaced the +ve lead and therefore the yellow connector.
the Battery is brand new
The Airbag in the dash still is stuck on
Gap IID somtimes gives an Airbag fault of 0x50 Supply less than 9.6v

I pulled the fuse 44 the airbag light remained on gap didnt give an error.

My MOT has expired and I am stuck.

Have you checked the voltage at fuse 44 as it looks to be fed by the ignition switch which are known to give problems.

backinblack said:

Have you checked the voltage at fuse 44 as it looks to be fed by the ignition switch which are known to give problems.


View attachment 306645

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I had pulled and checked fuse 44 but not checked the voltage across it, presumable it should be a nominal 12?
the error in Gap IID is voltage lower than 9.6 so i will look for a measurment above 9.6v

chu017 said:

I had pulled and checked fuse 44 but not checked the voltage across it, presumable it should be a nominal 12?
the error in Gap IID is voltage lower than 9.6 so i will look for a measurment above 9.6v

Click to expand...

Check one side of the fuse to earth.

backinblack said:

Have you checked the voltage at fuse 44 as it looks to be fed by the ignition switch which are known to give problems.


View attachment 306645

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Looks like we may be onto somthing,

pulled fuse 44 and measuring across the fuse holder.
top pin to the ground on the front aux socket (cig lighter)

Initially 8v rose to 9.8v with the engine running.

to me this is too low, presumably indicating a failing ignition switch?


can I feed a good 12v from elsewhere into that fuse location as a test?

Check the voltage both sides of Fuse 53 as well, in case the ignition switch feed is low.

pwood999 said:

Check the voltage both sides of Fuse 53 as well, in case the ignition switch feed is low.

Click to expand...

will measure that aswell

Fuse 53 gives the expected nominal 12v

I would say 12v is still a little low. should be more like 12.6v. What do you have at the battery?

backinblack said:

I would say 12v is still a little low. should be more like 12.6v. What do you have at the battery?

Click to expand...

Sorry my bad
It was 12.7v across fuse 53
9.2 across fuse 44

So you're dropping from 12.7 to 9.2 across the ignition switch. As a test, just connect F44 to F53 so the 12V gets to the ECU.

Then check faults. Might need to clear faults, and then read them again ?

And that has sorted it.
Thank you all for your help.

I now have bits to add to my spares shelf.

I will order a new ignition switch

I have since replaced the ignition switch and removed by bypass in the fuse board and all is well.
well got some other issues but those are seperate.
thanks all again.

re ignitions switches the LR part is the same as the BWM PN 6901961, which is usualy a fraction of the cost of the LR one.