If the Japanese had no ability to detect radar emissions the USN sub skippers did not know it and had to assume that they did. Indeed in several accounts USN sub skippers ordered their own radars switched off to avoid that possibility. SD was seldom used for this reason. I have read several accounts where USN sub skippers express much the same concerns about giving away their position by radar transmissions as German U-boat skippers did.
The Japanese sub skippers would have been well served to have practiced the same caution as the Americans or the Germans. According to Blair poor IJN radar discipline resulted in IJN subs being destroyed by American subs. The American subs had a radar detector known as the APR. The APR could detect the 10cm emissions of the radar used by IJN subs from distances of 5 to 10 miles. The American SJ radar had slightly longer detection range to a surfaced sub than the IJN radar did. So once the IJN sub had given itself away the American sub would close in detecting the IJN sub first and setting up a surprize torpedo attack.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.