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Hi everyone
Looking for a little guidance. It seems I have an issue when it rains/or damp not sure what really triggers it. That the electrics go a little mad 4ways/horn/wipers. So I checked the bcm no signs of water ingress or damp lots of dry dust though 😁 Now gonna take from seat out and have a look under there. Does anybody have any photos of what the wiring loom looks like there? My van is 2008 1.9tdi 102 LWB. The BCM is 7HO937049AB. Also if was to get a replacement is there much difference between an AB and AC bcm as don’t have ability to recode so would be plug n play?
All help appreciated.
 

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That the electrics go a little mad 4ways/horn/wipers.
It would definitely be worth checking the wiring under the driver's seat, but I think you are right to suspect the main BCM. IIRC the under-seat wiring is related to the Convenience Control module located there, so it will mainly affect locking and electric windows, but it's worth checking for corrosion damage - if only to head off a possible future problem.

I'm not sure what the "4ways" means, but the horn and wipers both wire via the main BCM, so it's a likely suspect. Typically (but not always) the letters AB and AC refer to revisions to the internal circuitry, and you ~should~ find that AC is backward compatible with AB. In terms of coding, there's not going to be anything to choose - if buying secondhand, compatibility will be determined by what coding was used in the original vehicle, not by whether it's AB or AC. But there are relatively few coding options on a pre-facelift, so you will probably find it works just fine. I can vaguely recall a problem if rear wiper(s) are coded but not fitted, but I would think the chances of it just working OK are pretty good.

{I should add that if the problem only affects the horn and wipers, the large connector behind the steering wheel could also be a suspect}
 
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