Advanced Diagnostics

Advanced Diagnostics - DTC P1746: Hydraulic Control System (Cut Valve A Stuck OFF Or Cut Valve B Stuck ON)











General Description
Cut valve A and cut valve B is installed in the hydraulic control circuit in the transmission. Cut valve A and cut valve B supplies line pressure and A/T clutch pressure control solenoid valve pressure to the 1st clutch or the 5th clutch. When the signal to shift solenoid valve A from the powertrain control module (PCM) is ON, and line pressure is applied to shift valve A, it operates against the shift valve A spring. When the signal to shift solenoid valve A from the PCM is OFF, and line pressure is discharged, shift valve A is inactive. Once cut valve A is activated, it is locked by line pressure which is supplied only when the shift lever is in the D. Cut valve A is switched to inactive side due to pressure supplied to the 1st clutch. When the pressure is supplied to the 1st clutch, cut valve B operates against the spring. When the pressure is not supplied to the 1st clutch, cut valve B is inactive. Once cut valve B is activated, it is locked by line pressure which is supplied only when the shift lever is in the D. Cut valve B is switched to the inactive side when the signal to shift solenoid C from the PCM is ON. The signal from the PCM is output to apply A/T clutch pressure control solenoid valve pressure to the proper gear change clutch according to the gear change schedule. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change which is decided according to the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, the cut valve A OFF failure or the cut valve B ON failure is detected and a DTC is stored.

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






Enable Conditions






Malfunction Threshold






Driving Pattern
1. Start the engine.
2. Drive the vehicle in D until the transmission shifts into 5th 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.