The tab is on the top of the plate that the motor bolts too. Its a HARD metal Tab about 1 cm wide by 2 cm tall. I had to bend mine back with a hammer and punch. What this does is the parking mechanism on the top of your wiper motor hits this and causes the motor to park you wipers. When its bent it will not catch causing your wipers to do strange and weird things like park in the upright position. I used to have pictures of this but i must have deleted them.

Good luck.