DTC P0743: Torque Converter Clutch Control Solenoid Valve Circuit Fault: Description
WARNING: This page is about a different car, the 2002 Mazda 626 and 2001 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
DTC will set if PCM detects TCC control solenoid voltage is remaining at battery voltage, or zero volts after engine is started, PCM determines that TCC control solenoid circuit has a malfunction.