The Senate Foreign Relations Committee voted 15 to 1 yesterday to restore the U.S. embargo on imports of Rhodesian chrome, and 12 to 0 to condemn Uganda's Idi Amin regime for possible complicity in the killing of Anglican Archbishop Janani Luwum.

A trade embargo against the white regime in Rhodesia was first voted by the United Nations a dozen years ago. It was an attempt to force the regime to negotiate with Britain over future democratization of the government to include black majority rule. IN 1968 the U.S. government, responding to a strengthened U.N. request, barred imports of 72 strategic materials from Rhodesia.

However, in 1972 Sen. Harry F. Byrd Jr. (Ind.-Va.) pushed through Congress an arms bill amendment forbidding the President to carry out the trade ban, on grounds the United States badly needed chrome from Rhodesia.

In 1973 the Senate voted to repeal the Byrd amendment, but in 1974 the repeal move was defeated in the House.

This year, however, prospects for repeal of the Byrd amendment appear improved, because Secretary of State Cyrus R. Vance has strongly endorsed the repealer and because some American steel interests have told House leaders that Rhodesian chrome isn't as important to the steel industry as it once was. New processes and new sources of chrome ore have appeared in the last few years, Senate aides said.

Written into the repealer is language to protect American steel interests from competition from imports using Rhodesian chrome. In effect, it would bar imports of steel mill products using Rhodesian chrome as well as imports of the ore itself and various forms of it. Nations exporting steel mill products to the United States must certify that they don't contain Rhodesian chrome.

House Democratic Whip John Brademans (Ind.) said chances of House passage this year are "better, because the President has made plain he is clearly committed to repeal. Other administrations just gave lip service."

Sen. Clifford P. Case (R-N.J.) sponsored the sense-of-the-Senate resolution condemning the Uganda regime's "violations of human rights" and asking for a U.N. investigation of Luwum's death.

The Uganda government says Luwum and two others were killed in a car crash after being arrested, but some reports say they were murdered.