Originally Posted by MetalMuffins
I am note sure on the wiper needing a certain amount of fluid on the glass before starting as mine will start wiping before any fluid is sprayed onto the glass. This is probably because it has been -30C for the past week
Its not that its determining a certain amount of fluid or not, more so that if you don't hold the spray/ wipe switch forward long enough it won't swipe at all despite spraying fluid until after a certain time delay, where as just energizing the wiper with the toggle switch works right away every single time.
This is the same as the front windshield sprayers, if you don't hold the switch long enough it doesn't actually activate the wipers even though it may have sprayed fluid. That is a common occurence on any car I've ever had.