Ive traced the voltage throughout the wiper system. All seems good to the wiper motor.  When switch is on I only get a click.

Check the ground at the wiper switch.  Our C3 wipers are always hot with the key on, and are turned on by controlling the ground with the wiper switch.  It the switch is not grounded where it mounts, not a seperate ground wire, the wipers wont work.

not to hijack the thread but can you tell me how/where the switch is grounded?

My diagram shows a dark blue wire going to ground but I havent found the end yet.

The switch grounds itself to the dash/gauge panel it is attached to. So...if the switch is loose, or the panel is not screwed into the metal of the dash nice & tight, the switch won't provide a ground for the wipers. More than one person has spent many hours attempting to check wiper operation with the dash apart, give up, put everything back together, and NOW the wipers work!
Make sure the switch is properly attached to the dash panel before anything else. Some folks will run a separate ground from the metal of the dash up to one of the screws on the switch...that way it always has a ground, in case the dash/gauge panel loosens up...Adams' Apple2008-09-02 10:20:19

Add me to the list.......put everything back together and now they work. It had to be exactly what you meantioned. Just reconnecting must have secured the ground.

Well now...I do NOT always have all the answers...but I can lie or make something up with the best of them!

Glad ya got them working, anyway. This is how we learn...trial and error. We've ALL been right where you are at some point.

Go forth, Grasshopper, and share your knowledge with others...