American Motors Corp. and French automaker Renault have called a news conference for Wednesday, apparently to announced a final agreement on their joint automotive venture.

The companies are expected to disclose firm plans to sell the Renault Le Car in this country and AMC Jeeps in Europe and a timetable for building a Renault sedan at AMC's Kenosha, Wis., assembly plant.

AMC would only say today that "an announcement of major importance" was planned with Renault, which is owned by the French government.

Meanwhile, Chrysler Corp. today denied it has approached the Mitsubishi group about the possibility of the Japanese firm purchasing 15 percent equity in Chrysler.

The Yomiuri Shimbun, a Japaneselanguage newspaper, reported earlier today that Mitsubishi President Tomio Kubo and other executives have gone to Palm Springs, Calif., for a meeting with Chrysler President Lee Iacocca "to study the possibility,"of such a deal.

Chrysler denied the report. A spokesman said the California meeting was a "get acquainted session" between Mitsubishi leaders and Chrysler's new president.

The AMC-Renault negotiations had dragged on for more than nine months since the companies announced their tentative plans last March 31. The protracted talks produced wide speculation in the industry that the deal might fall through.

Both companies repeatedly dismissed such talk, saying that the project had simply turned out to be more complicated than they expected. Analysts note that since disclosure of the initial agreement, AMC has accomplished several things on the labor, financial and production front that probably reassured Renault.

The smallest U.S. automaker tripled its modest profits from $8.3 million in 1977 to $36.7 million in the fiscal year ended last Sept. 31.

Sales of passenger cars continue to be a money-losing proposition for AMC. The firm's share of the U.S. auto market slipped to 1.8 percent in 1978 as sales declined nearly 8 percent.

But Jeep sales leaped 40.7 percent and are expected to equal car sales in 1979. With its higher Jeep capacity, the vehicles are expected to boost profits again this year for the company as a whole.