P2764 LOCK-UP DUTY SOLENOID CIRCUIT (LOW)
1. OUTLINE OF DIAGNOSIS
• Detect the GND-output short of the lock-up duty solenoid drive circuit.
The TCM applies power to the torque converter lock-up clutch solenoid to in order to lock the torque converter. This is usually initiated after the car is moving and the transmission gear ratio starts to reduce.
The TCM monitors the voltage at its terminal that connects to the solenoid. When the TCM is not engaging the lock-up clutch, there should be very little voltage, and when it is, there should be system voltage (e.g., 10 -14 V).
The P2764 code is indicating that in the latter case the voltage remains low, instead of being in the 10 – 14 V range.
This could be caused by a fault in the TCM driver circuit, a short to ground in the wire from the TCM terminal to the solonoid, or, in the solenoid itself.
The code doesn’t necessarily mean the solenoid, and therefore the valve body, has to be replaced, at least not until further troubleshooting is done to determine if there’s a fault in the TCM or in the wire to the solenoid.
Although Subaru does not provide, or replace, individual solenoids for the CVT transmission, some here have found aftermarket sources for the torque converter lock-up solenoid. @Brucey has done this, and has a video on it.
Except that the torque converter is probably not locking as it should, and that will cause heat build up and, over time, increased wear on the torque converter, as well as greater fuel use.
