BSM has pin broken off in under-bonnet fuse box

I have a C3 1.4 Desire on an 04 plate.
I started having an issue where the rear screen heater has stopped working, plus the airbag lights come up permanently on the dash. Having investigated I have found that one of the connector pins has corroded/broken off from the under-bonnet fuse box. It is one of the pins to the ten-pin black connector and has a yellow wire going to it.
I am looking to get a secondhand replacement fuse box on a well known auction site but am unsure of something.
Some people suggest that this wont be a straightforward swap as there will be an issue with the BSI, but i thought that was in the cabin fuse box. Can anyone advise whether or not i can just replace the whole box or will I have issues.
Many thanks
Paul

Its a straight swap, no programming required.

Lots of BSM B3 here, if you need one.

Great stuff, many thanks for that and the link.

Any idea what the yellow wire to the the pin connector actually feeds.

Regards

jtscoot wrote: ↑Thu Feb 13, 2020 10:57 am Any idea what the yellow wire to the the pin connector actually feeds

I will need the wire number (its printed on the insulation) and the plug colour, the number of wires on that plug AND the pin number for the yellow wire on the plug. The pin numbers are on the connection side of thr plugs,so you need to disconnect the plug to see them.

Hello Arfur,

It is a ten-pin black plug. Pins 1, 3, 4, 5, 8, 9 and 10 are taken (7).

The broken one is pin 5.

The yellow wire number is difficult to read but I can just make out A7 and 2343 if that makes any sense. can get a beter look if necessary with a magnifying glass and when the rain stops.

Pin 5 of the black connector is one of the comms bus lines to/from the BSI.

It should be labeled 901 3A.

The 2XXX wires should be for the headlights.

The rear demister is run from the BSI.

The air bags are not directly connected to the BSM but a bus failure might give the BSI a headache and bring the light on but that's a very big stretch!

I cant see any connection between the BSM and your faults. The BSI has more in common but I don't think they are related.

With that pin missing the BSM shouldn't be doing much and a lot more system should not be working. Have you plugged the BSM back in since then? Everything (except your faults) work when you plug the BSM back in?

Just a quick update on my issues.

I managed to get a replacement fuse box online and after a break in the weather, finally managed to get it fitted after some access issues given where it is located under the wing. The issue with the airbag warning lights has now been resolved, with nothing coming up on the dashboard.

I think that the rear demister is still not working and will get my multimeter out to check power getting to it.

Thanks for everybody's input.

Ozvtr wrote: ↑Thu Feb 13, 2020 7:08 pm
The air bags are not directly connected to the BSM but a bus failure might give the BSI a headache and bring the light on but that's a very big stretch!

A review of my data shows the airbag ecu is on the body VAN1 bus with the BSM but so is the COMMs 2000. Did you have any trouble with the indicators, headlights, wipers etc? Any other funny symptoms (apart from the rear demister)?

The only issues were around the airbags and the rear demister. A couple of months ago I did have an odd issue where the rear screen wash pump once activated continued pumping until the bottle was emptied. I sorted this by resetting the BSI.
All else seems OK