The 2012 Honda Civic will remain in short supply until at least the coming autumn.

Toyota’s entire U.S. production network will be sitting idle next week, the maker deciding to stretch out the normal Memorial Day holiday break because of ongoing shortages of Japanese-made parts.

Honda, meanwhile, says that while its global factory network appears to be recovering faster than it first anticipated it will be facing more problems getting production up to speed for the new 2012 Civic model, which is likely not to reach normal volumes until “sometime” in autumn.

A new report underscores the magnitude of the crisis touched off by Japan’s March 11 earthquake and tsunami.  In Japan, Toyota production was off by 74.5% for all of April, while its global production declined 48%.

The disaster had only marginal impact on automotive assembly plants but 100s of supplier facilities were damaged or destroyed.  Others have been struggling under the rolling blackouts implemented after the quake touched off a triple meltdown at the Fukushima nuclear plant.

Toyota, which is heavily dependent upon a Japanese-centered production system, suffered the biggest loss of production, about 350,000 vehicles in total for April.  But Honda also was impacted quite severely, losing 81% of its Japanese production and 52.9% of its worldwide output for the month.  Nissan, with a smaller domestic Japanese production base saw home market production fall 48.7%, and its global output drop 22.4% for April.

With their automaker clients – both Japanese and foreign – lending support, Japanese suppliers are coming back online faster than many analysts had feared.  A key pigment plant run by Merck resumed operations this month and a major source of automotive computer chips run by Renesas is expected to begin limited output shortly.

Nonetheless, supplies are still short, and depending on the individual part and vehicle, production remains well below normal capacity.

Toyota idled its entire Canadian production system this past week, and will close all of its U.S. plants for an extended Memorial Day holiday next week.  The maker expects overall North American production to be at 70% of normal for June and July, with eight models back to normal levels.  Still running slow are the RAV44, RX350, Tacoma and Tunda nameplates.

Honda, which operates seven plants in the U.S., Canada and Mexico, will be operating at about 50% of its North American capacity in the weeks ahead.  Unfortunately, for the maker one of the products hardest hit is the new version of its Civic compact, which had been in high demand as it came to market just as the quake struck.

The Civic is assembled in two plants, one in Indiana, the other in Ontario, and those operations are not expected to resume normal production levels until “sometime in the fall,” Honda stated.

Despite that setback, the automaker’s chief U.S. executive issued an upbeat assessment, declaring, “The light at the end of the tunnel is glowing brighter for us, represented by this significant improvement in our production situation.”