TSB - SERVICE ACTION: TRANSMISSION GEAR SHIFT LOGIC IMPROVEMENT (SA337) - This bulletin provides the procedure to improve the logic of the Transmission Control Unit (TCU) on some 2017-2018MY Cadenza (YG) vehicles, produced from June 2, 2016 through August 18, 2017, which may experience unusual 5th gear engagement instead of 1st gear after starting the engine and shifting from Park (P) to Drive (D).