The Reagan administration is preparing to send an interagency group of officials to Tokyo next week to discuss with the Japanese government the problems of the U.S. auto industry and how the administration plans to help it, according to administration sources.

Although the plans made last week haven't been finalized, the group is expected to consist of representatives of the Office of the U.S. Trade Representative and Departments of State, Commerce and Transportation. They would not negotiate any import limitations with the Japanese, but would brief them on the adminstration's auto industry task force report, the sources said. No agreement is expected to result from the several days of discussions, sources said.

Last week Secretary of State Alexander M. Haig Jr. and Japanese Foreign Minister Masavoshi Ito announced that the two countries had agreed to hold further high-level discussions on the issue in Tokyo and Washington.

The Japanese had said they wanted a briefing on how the U.S. government is helping its industry and what President Reagan's economic recovery plan will do. They said areas to be discussed would be "the extent of the public-opinion situation in both countries, what the United States plans to do domestically in response to the situation and the legal considerations which exist on both sides."

And discussions would be led by U.S. Trade Representative William E. Brock, an administration spokesman said last week. But sources said yesterday that a representative from Brock's office, rather than Brock, will go to Tokyo next week. All participants at the talks will be from the deputy assistant secretary level, sources said.

Meanwhile, Sen. John C. Danforth (R-Mo.) yesterday asked Senate Finance Committee Chairman Bob Dole (R-Kans.) to speed up action on his bill placing three-year import quotas on Japanese automobiles.

Sources said that Danforth's message will be heard by the Japanese as well as by Dole and that it should help the U.S. position in any discussions.

The Danforth-Bentsen bill would limit imports of Japanese cars for three years to 1.6 million about 300,000 less than sold last year.

Sources said they didn't know what response, if any, the Japanese would make to the Americans presentation. The Japanese have said on several occasions that they don't want to be blamed for Detroit's problems. What they would like, sources said, is to be able to say that the U.S. government is taking a lot of actions to help its own auto industry, and the Japanese will voluntarily help them out.

The Reagan administration's auto industry task force has recommended that the government signal the Japanese to voluntarily restrict their imports rather than have legislated quotas. In addition, the government will propose modification of environmental and safety regulations that add hundreds of dollars to the price of American cars.

An announcement on the regulations had been planned for Friday, but that could change as a result of the assassination attempt on the president on Monday, sources said.

Danforth, who cosponsored the legislation with Sen. Lloyd Bentsen (D-Tex.), said he "would like to see the administration's efforts" to reach agreement with the Japanese government on import limits continue.