P0729

DTC P0729 6th gear ratio abnormal

Circuit description

The transmission control computer ASSY detects the gear position based on signals from the transmission revolution sensor (NT) and the transmission revolution sensor (SP2). Then, the transmission control computer ASSY detects mechanical problems of related solenoid valve, valve body, or automatic transmission when the detected gear position differs from the commanded position.
Shift to 6th gear is prohibited as fail safe.





Monitor description

TCM switches ON/OFF of the shift solenoid valve and transmits oil pressure to the valve body to command gear shift. This diagnostic code indicates that the sequence valve is locked in the direction the spring extends and shift to 6th gear is impossible.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS
The following items are common to the all conditions below.





TYPICAL MALFUNCTION THRESHOLDS
Compare the target gear specified by TCM and the gear ratio calculated from turbine shaft speed and vehicle speed.
When both of the following conditions are established: condition (A) and (B)

Condition (A)





Condition (B)





When both of the following conditions are established: condition (C) or (D)

Condition (C)





Condition (D)





Gear positions when mechanical problems occur in reverse sequence valve





Inspection steps