I guess the traditional answer would be an insulating (usually petroleum) grease/jelly (Vaseline). Not sure about its compatibility with modern plastics etc though.

Possibly a better approach is to look at why water is getting into or pooling in the system in the first place - modern design normally do take moisture into account, so maybe it's more down to a missing/damaged/displaced O-ring or a blocked drain hole or something of that nature.

   - Andy.

Hi Andy, thanks for the reply.  This is a known fault on the Ford Transit Customs. I'm pretty sure washer fluid is able to find its way down to the back of the connector that plugs into the wiper motor control module in the photograph. The fluid is effectively funneled down through the non waterproof connector ending up at the module connecting pins where it stays and corrodes. The reason for my post is that we have worked on desert ralley (Dakar) motorbikes in the past which have also suffered from extreme conditions and were wondering if there was something other than the usual treatments like petroleum jelly or grease that would inhibit corrosion. 

Washer fluid is probably more active than fresh water as well. The problem as always is that anything other than a perfect seal is a trap, and worse than being open  We have been known to pot the topsides of wire end connectors, but this needs care, as it the compound can migrate into  the contacts if the connector body not designed for it. Hot melt glue is a cheap alterntive, but again take care not to create a water trap and make it worse.

The other alternative might be some of the sealing compounds they sell for joint boxes - the stuff that sets to a weak jelly - e.g. https://www.tlc-direct.co.uk/Products/WKMPSG170W.html which could provide a good seal in awkward shapes, but again probably needs to be kept away from the actual contacts until it's set.

   - Andy.

Or perhaps the horrible gel-box ?

https://www.tlc-direct.co.uk/Products/WKMJB2.html

about as removeable as chewing gum....
Mike.

We have also used liquid insulation and ended up with it completly filling and isolating the connecting pins. 

How accessible is the connector? If it is not too difficult, regular spraying with WD40 might help.

Vaseline was the traditional stuff for battery terminals.

That connector seems to be unfit for purpose. There are ones which look a bit like an accordion which are, presumably, waterproof.

(Does it rain in Dakar?)

I would use silicon grease as an alternative to vaseline, the sort that is sold for potable plumbing.

Very limited access, in fact you can't really see the connector block and you certainly can't see into the module receiver block as it's facing the firewall just tucked under a steel shelf below the windscreen. The whole motor assembly has to be stripped out to really get at it.  And yes, In my opinion, it's not fit for purpose.  Sorry to be critical but it has the potential to have windscreen wiper and windscreen washers failure while driving.  Ford know this.  That may be ok at slow speeds and were you can pull over but not so good in heavy rain on the motorway.  Ford has advised me it's a known fault but not as yet a recall item.  The failure of the unit usually stops both the windscreen wipers and windscreen washers, both an MOT test item. 

The Dakar hasn't been to "Dakar" for many years and has been moving around, South America for a while and Saudi this year.  I think the worse instance was 2015 heavy rain in Bolivia on the salt flat stage.  The rain turned the salt into brine and instantaly attacked the softer metals.  The liquid acted like an electrolyte and sent power throughout the electrical system lighting them up like a christmas tree.  Even the factory teams had retirements that day.  I've rebuilt a ralley bike that was airlifted out from that stage.  It was toast. Couldn't believe the damage in such a short space of time.  

Wouldn't silicon reduce conductivity?