LOOK UPON the contest between Congress and South Korea over the testimony of Kim Dong Jo as an exercise in mutual face-saving. Congress, to save its face, needs to show it can rigorously investigate allegations of legal and ethical violations by its own members. Hence its effort to obtain testimony from Ambassador Kim, suspected of passing cash to as many as 10 current representatives. But Korea, to save its face, needs to show it cannot be compelled by threats of an aid cutoff to waive its treaty-protected right of diplomatic immunity and deliver up the envoy. Hence Korea's refusal so far to make Ambassador Kim available under terms acceptable to the House.

The House International Relations Committee, as we understand it, has been trying to move toward the joint objective. To that end, the committee yesterday denied the plea of Special Counsel Leon Jaworski to report out a resolution withholding noneconomic aid until South Korea coughs up the ambassador for interrogation under oath. That was excessively blunt. The Vienna Convention, a treaty, guarantees diplomatic immunity. The United States should not expect another country to yield its protections. Nor should the United States set a precedent the could expose its own envoys. Rather, the committee focused on an approach calling on Seoul to provide Ambassador Kim and suggesting, but not mandating, that if Seoul does not provide him on terms helpful to the House inquiry, the House will take that into account when dealing with aid.

Such language is not the stiffest, but it could, we believe, provide Mr. Jaworski with the "muscle from Congress" he has insisted he needs. In any event, the way Americans read a House resolution is not so important as the way Koreans read it. The language is being designed to enable Korea to respond positively without an unacceptable loss of prestige. There is an element of pressure, for which Americans need not apologize, but there is an element of respect, too.

With strong House approval for this approach, the onus will then be on the Koreans. Can they really wish to have the whole range of their relations with their principal patron treated for an indefinite period in the light of a refusal to satisfy the requirement s of a legitimate inquiry, one provoked by their own behavior? It is not, after all, as though payoffs to legislators were normal diplomatic activities of a sort meant to be protected by diplomatic immunity. If the allegations against Ambassador Kim are as flimsy and unfounded as his defenders aver, his inconvenience should be slight. And if that turns out to be not so slight, then surely it will be worth Korea's longterm while to do what it can to ensure that smooth Korean-American relations are restored.