Today I used some engine degreaser and cleaned the engine myself. Sprayed it down, let it soak, and then I washed it off with the hose. I covered the alternator and the coil pack with plastic bags. I didn't spray directly into electrical connetions. Everything dried and it looks nice now. However, now my left turn signal comes on, but does not flash. My right signal works and flashes as it should. ANy ideas on what's causing this? Do you think it's a coincidence that my flasher started to die on the same day I did this?

Check to see if you have a burned out bulb. If not replace the flasher. It is most likely just coincidence that the flasher or bulb failed, but who knows, I've seen stranger things happen.