I know that this is a bit late but you should consider your combination relay, this is a computer with a few relays stuck inside. You have to remove the top of the fuse box to get at it and it's a biggie.

It controls the wipers, indicators, hazzard flashers, rear demister AND YOUR INSTRUMENT CLUSTER!

They are prone to failure and aren't a bit cheap. There are three connectors on the underside, you could reseat them. Don't force any connectors off! They are hard to see and get at but two connectors with fewer wires pull off but the big one has a safety sliding mechanism which can only be released after removing the pull off connectors.

My wipers have gone a bit nuts, they sometimes run and change speed all by themself. So far I have replaced the wiper relay and 3 (yes three), combination relays. If I can't get it sorted this weekend, I am going to build my own wiper control system with less logic (but also less fail safe).

M