I'm currently restoring one of these myself. The Pinto shares its wiring (and almost everything else) with the Puch Maxi. So, you can use Puch Maxi service manuals and wiring diagrams, which are available on ebay and from places like themopedjunkyard.com.
Most Puch maxi parts are compatible too, except for the side covers and air filter (from the Puch Magnum), gas tank and fuel valve. Good luck!