You might have a chance, nothing's guaranteed though. Lately around the GTA, some officers have been saying they will "help you" if you take it to court. Could mean anything. They are tending to show up more often than not, although in one previous incident mentioned on this website, an officer with the Peel Police said similar stuff, showed up for the court date and then (accidentally I'm sure) provided the wrong notebook. 
Couple of things... was your view of the sign blocked by something or did you just miss seeing it? Also, I'm assuming this happened in Richmond Hill, right?
Probably the most critical step, other than actually setting up to fight the ticket (get the court date, etc) is to request disclosure so you can get the officer's notes; also ask for an "explanation and clarification of the charge." You might've read about the bilingual defence... unfortunately York Region is NOT a designated bilingual area so even if the sign is English only I don't think that will help.