Good afternoon all,

 

Hope you are all well. I'm looking for a bit of advice on swapping the BCM in my 2002 9n polo.

 

It has been sitting on my drive for the past 2 years, but my dad has purchased it from me and trying to be helpful I said I would put it through an MOT before I got it to him.

 

Going back 2 years when I was still using it, I used to have a random issue where my wipers wouldn't work on intermittent, but would work on the faster speeds. I didn't bother looking into it too much at the time as I could work around it. Eventually the wipers wouldn't work on any setting on rare occasions, and when this happened I replaced the motor and the stalk, thinking these may be the issue. They weren't and the problem didn't go away. I soon after got myself a new motor and forgot about it.

 

Well anyway, it failed it's MOT because the wipers wouldn't work. I used them on the way to the MOT centre and they worked fine. Lo and behold, when they got in for the test they packed up. 

 

I did a bit of research and assumed that the issue may lie with the micro switch on the bonnet release catch. After some digging about there, use of a micrometer and a bit of work with a paperclip I tried to bypass this switch even though the micrometer was pointing at it working just fine. None of this solved my issue with the wipers. 

 

I know from before that on these there's no separate relay for the wipers, it is all controlled by the BCM. I managed to source a like for like BCM from a great breakers on eBay.

 

As the code is exactly the same code (6Q1 937 049 C), I am hoping that it will simply be a case of plug and play with the SH one. Can anyone confirm?

 

I found a thread on a forum somewhere where someone did the same, like for like, and it didn't need recoding and all of that palaver, but I can't find a lot on it as most posts people are generally only swapping the BCM to upgrade something, which does require coding.

 

I'm going to try to fit tonight, I don't have any of the VW software or anything so am just going to try and hope for the best. If in the worst case scenario it does need recoding, could someone put the original back on and retrieve the codes from that? My dad who is having it has a mate who is apparently a VW man who should be able to do this, but I'm hoping I can get it through the MOT first.

 

Any advice or words of wisdom will be much appreciated. Cheers!

Alex

Firstly, check all your fuses, there's three different ones that can affect the wipers. I got caught out on a Fabia a few months ago. Think it was fuse 15.  

 

The other candidate is the relay, but it's not a trivial one to change. I'll find the guide when  on the computer tonight. 

 

If you're doing a BCM swap, chances are, you'll need to read the coding of the existing bcm then code the new one to match. Just doing a  plug and play is a gamble, might work, might not. 

 

BCM's don't generally fail for no reason, but being where they are, they can suffer from water ingress.

 

 

43 minutes ago, Yeti said:

Firstly, check all your fuses, there's three different ones that can affect the wipers. I got caught out on a Fabia a few months ago. Think it was fuse 15.  

 

The other candidate is the relay, but it's not a trivial one to change. I'll find the guide when  on the computer tonight. 

 

If you're doing a BCM swap, chances are, you'll need to read the coding of the existing bcm then code the new one to match. Just doing a  plug and play is a gamble, might work, might not. 

 

BCM's don't generally fail for no reason, but being where they are, they can suffer from water ingress.

 

 

Thanks Yeti.

 

I have been through all of the fuses before- I have read they can be tricky buggers. What led me to believe it wasn't fuses before, was that if I was to switch the car off and on again they would work. This hasn't saved my bacon this time though, so I will revisit fuses tonight.

 

Appreciate you looking into the relay, thank you.

 

I'll try to update tonight on fuses and BCM swap tonight. It's bloody cold and damp out, I've got a cold myself and don't really fancy it but I need to get it done.

Just swap it, it'll work well enough to pass MOT, unless the relay on the replacement happens to also be worn out, I'd say.

The coding tends to be for the 'frill' functions rather than fundamentals,  I think.

 

I could read the code out of the original with it out of the car, and replace the relay, but I suspect you'll need neither with a bit of luck.

 

This page shows the coding items

http://wiki.ross-tech.com/wiki/index.php/VW_Polo_(9N)_Central_Electronics

 

Coding is the sum of all the fitted items/features.

Well Pete, you were right.

 

The like for like replacement went swimmingly, the wipers work again, it passed the MOT and now I've sold it to my dad for the scrap price. It lives on! 

 

No issues at all since the BCM swap.

 

Thanks all for your assistance.

😁

 

Don't suppose you've still got the BCM that came out?