Toyota’s quarterly profit crumpled more than 75% after the March earthquake and tsunami wiped out parts suppliers in northeastern Japan, severely disrupting automobile production.

The manufacturer gave no forecast for the current fiscal year through March 2012, citing an uncertain outlook because production continues to be hampered by a shortage of parts.

The company president Akio Toyoda said he and others at Toyota are “Gritting our teeth” to keep jobs in Japan. He promised to disclose earnings forecast by mid-June.

Toyota Motor Corp. reported on May 11 that January-March profit slid 25.4 billion yen from 112.2 billion yen a year earlier. For the fiscal year ended March 2011, Toyota’s earnings doubled, showing that the car manufacturer had been on the way to recovery from its recall crises when the magnitude -9.0 earthquake struck on March 11.

But Toyota also said efforts to fix production, including using other plants and finding replacement parts, were going better than initially expected, with car production expected to gradually pick up in Japan and abroad from June to 70% of pre-disaster levels. “We have successfully reduced the number of critical parts for a vehicle from 150 types as of April 44 to only 30 types today,” said Toyoda.

“Our priority is to get our production back to normal and recover from the disaster,” a sombre Toyota told reporters.“By reviving our company, we want to help bring Japan’s comeback.”

Nissan Motor Co. rounded out a record year for car sales by returning to profit in the fourth quarter but CEO Carlos Ghosn acknowledged serious challenges from Japan’s natural disasters.

The good news was clouded by uncertainties due to the damage from March quake, tsunami and nuclear power plant‘s accidents that have disrupted production for Nissan and other Japanese manufacturers.

Ghosn said production at Nissan plans worldwide will be back at pre-disaster levels by October. He did not give an earnings forecast for the current fiscal year, but promised projections would be ready by a shareholders’ meeting in June.