The AFL-CIO, with bipartisan support and the backing of a business coalition, said yesterday it will launch a major lobbying effort to pass a trade "modernization" act aimed at stemming the flood of imported goods that has caused the loss of an estimated 3 million American jobs.

House Majority Leader Jim Wright (D-Tex.) told a gathering of 1,200 AFL-CIO political activists here yesterday that it is "time for action" in Congress to reduce the record $123 billion annual trade deficit, although Wright said afterwards that he has not yet seen the labor-backed legislation and could not comment on it.

The Trade Law Modernization Act -- which AFL-CIO officials said would be introduced shortly with at least 30 bipartisan sponsors, including Sen. John Heinz (R-Pa.) -- would require "reciprocity" from foreign governments to open their markets to American goods if the United States gave open access to their products.

The bill, drafted by the Labor-Industry Council for International Trade, also would require that industries given special "temporary protection" from imports modernize and develop "a strategy to enhance competitiveness."

A labor, management, government advisory group for the affected industry would oversee such a program.

Howard D. Samuel, president of the AFL-CIO industrial union department, said this key provision is intended to stop industries from "taking the money and running" by achieving higher profits through import protection, but then investing elsewhere.

He cited steel firms winning protection, but then buying oil companies with higher profits.

Samuel cochaired the labor-industry council of 10 unions and nine corporations that drafted the bill. Corporate backers of the legislation include such import-sensitive giants as American Telephone and Telegraph Co., Westinghouse Corp., Bethlehem Steel, B. F. Goodrich and W. R. Grace & Co.

"I think it is historic that we have a unified position on the trade issue, unity within the labor movement and significant participation from employers," Lynn Williams, president of the United Steelworkers of America, told the AFL-CIO legislative conference at the Shoreham Hotel.

Labor officials conceded that the bill would have an uphill fight against the Republican-controlled Senate and the Reagan administration, which has said that most of the protections recommended would damage American industries because foreign governments would retaliate by blocking access to American goods.

Consumer prices also would rise if imports are restricted, the administration has said.

The bill is aimed at providing tougher and quicker remedies for illegal "dumping" of foreign goods and for retaliation against countries that practice "targeting," in which foreign governments subsidize and provide tax breaks to their industries so they can target American markets with lower-cost goods.

Presidents of several major unions, including Williams, William Winpisinger of the Machinists union and William Bywater of the International Union of Electrical Workers, testified on such trade abuses at hearings yesterday held by Rep. John Dingell (D-Mich.), chairman of the House Energy and Commerce Committee.

The bill would shift greater authority from the president to the U.S. trade representative to impose restrictions on foreign imports, a move that the authors of the bill said is intended to shift the rationale for trade decisions to economic rather than political grounds.

The modernization of trade law would create a "more assertive" trade policy and restore to Congress its rightful control over foreign commerce, said Rep. Frank Guarini (D-N.J.), a cosponsor.

He said that obsolete methods for achieving trade relief are so time-consuming "that the damage [to American industry] is irreversible."