Most modern vehicles use a Torque Converter Clutch (TCC) which is controlled by the Power Train Control Module(PCM) by means of a solenoid, this is in order to regulate the amount of slip that may have between the engine and the transmission.
The design of the TCC is made for better transmission efficiency during high speeds. Also, control the heat.
Diagnostic codeP0743 OBD II is set when the PCM detects a voltage outside the expected range in the electrical control circuit of the TCC. In general, this code is generated by an electrical fault of the TCC solenoid or its control circuit.
Constant transmission slip during abrupt acceleration.
Other codes related to the transmission may be present.
Overheating of the transmission.
Increase fuel consumption.
Causes of OBD2 P0743 Generic
In order for the DTC code P0743 OBD2 to be established, the following must occur:
Connections or connectors worn, corroded or defective.
Torque Converter Clutch (TCC) solenoid may be in poor condition.
Perhaps the transmission fluid is contaminated.
Possible solutions of the DTC code P0743 Generic
The relevant repairs to fault code P0743 OBDII are:
Make a diagnosis of the general condition of fluids. See if the level of it is fine.
Inspect the cables and connectors of the external transmission. Also, check if the fuses are in good condition. Also, check that the transmission case has a good ground and battery voltage.
Locate the cables that correspond to the Torque Converter Clutch (TCC). In general, there are two cables: one for voltage and another for ground. Apply power and check if the solenoid clicks. In case the solenoid does not produce any sound, you should check the continuity through the solenoid. It also verifies the continuity that goes to and from the sensor cables. The solenoid must have a reading between 0.2 to 0.5 ohms, although this varies depending on the manufacturer. Therefore, consult the specifications and compare with the readings obtained, repair any defect you find.