DTC P0734: 4th Gear Incorrect Ratio: General Description

To engage 4th gear, line pressure is supplied to the 4th clutch piston, engaging the 4th clutch, and the secondary shaft and the secondary shaft 4th gear are connected and revolve together. Hydraulic pressure is supplied to the 4th clutch through the ATF strainer → the ATF pump → the regulator valve → the manual valve → the shift valves → the feed pipe → the 4th clutch piston. (A shift valve failure in the supply route above is detected by the malfunction detection of each shift solenoid valve.) The powertrain control module (PCM) computes the ratio of the input shaft (mainshaft) speed to the output shaft (countershaft) speed. When the ratio is not the 4th gear ratio, the PCM detects a malfunction of the hydraulic circuit or the 4th clutch and stores a DTC.