Advanced Diagnostics

Advanced Diagnostics - DTC P0734: Problem in 4th Clutch and 4th Clutch Hydraulic Circuit










General Description
To engage 4th gear, line pressure is supplied to the 4th clutch piston, engaging the 4th clutch, and the mainshaft and the mainshaft 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.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold
The actual gear ratio must match one of these conditions for at least 12 seconds with the 4th gear command:
- Actual gear ratio is greater than the 4th gear ratio by a factor of 1.2.
- Actual gear ratio is less than the 4th gear ratio by a factor of 0.75.

Driving Pattern
1. Start the engine.
2. Shift to D, and drive the vehicle at a speed of 10 mph (15 km/h) or more for at least 12 seconds in 4th gear.

- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, a Confirmed DTC and the freeze data are stored. The MIL does not come on.

Conditions for clearing the DTC
The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.