Tokyo, April 2 (BridgeNews) - Japanese manufacturers turned pessimistic about business conditions in March after showing optimism in December, the Bank of Japan said in its quarterly short-term economic "tankan" survey of enterprises. The BOJ said its diffusion index (DI) for major Japanese manufacturers stood at -5 in March, versus +10 in its December survey, while the DI for non-manufacturers stood at -13 in March versus -10 in December. The March major makers DI at -5 was worse than the average market forecast of +1, from a survey conducted by BridgeNews.