Advanced Diagnostics

Advanced Diagnostics - DTC P0729: Problem in 6th Clutch and 6th Clutch Hydraulic Circuit










General Description
To engage 6th gear, A/T clutch pressure control solenoid valve pressure is supplied to the 6th clutch piston, engaging the 6th clutch, and the input shaft (mainshaft) and the input shaft (mainshaft) 6th gear are connected and revolve together. Hydraulic pressure is supplied to the 6th clutch through the ATF strainer --> the ATF pump --> the main regulator valve --> the manual valve --> the A/T clutch pressure control solenoid valves --> the shift valves --> the feed pipe --> the 6th clutch piston. (An A/T clutch pressure control solenoid valve failure and shift valve failure in the supply route above are detected by the malfunction detection of each 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 6th gear ratio, the PCM detects a malfunction of the hydraulic circuit or the 6th 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 6th gear shift command:
- Actual gear ratio is greater than the 6th gear ratio by a factor of 1.25.
- Actual gear ratio is less than the 6th gear ratio by a factor of 0.8.

Driving Pattern
1. Start the engine.
2. Drive the vehicle at a speed of 8 mph (12 km/h) or more for at least 12 seconds in 6th 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.