Diagnostic Trouble Code
P0743
Torque Converter Clutch (TCC) Solenoid Circuit Electrical
Technical Description P0743
Torque Converter Clutch (TCC) Solenoid Circuit Electrical
What Does This Mean P0743?
This diagnostic trouble code is set when the Engine Management Computer (EMC) also known as the Powertrain Control Module (PCM) and also known as the Engine Control Module (ECM) detects a fault with the torque converter clutch (TCC) solenoid electrical circuit, which is contained inside the transmission.
An automatic transmission is not 100% efficient because it is a fluid coupling that connects the engine to the rest of the internal transmission parts. The torque convertor transfers power using hydraulic force and it is internal to the transmission assembly. With that transfer of power comes excessive heat. The lockup torque converter was designed to make the transmission more efficient at highway speeds and to control heat. The torque convertor clutch is what lockups the convertor. Heat kills transmissions. That is why you hear that stop and go traffic is hard on a automatic transmission
The converter clucth does not lockup at these low speeds therefore heat is generated. This clutch is controlled by an electrical solenoid. The torque convertor clutch is locked changing the fluid coupling to a mechanical one. This solenoid uses power and ground sent through a coil of wires which creates a magnetic field to pull or push a central metal rod. When the solenoid is energized or de-energized, it directs fluid flow through the valve body of the transmission.
An automatic transmission is not 100% efficient because it is a fluid coupling that connects the engine to the rest of the internal transmission parts. The torque convertor transfers power using hydraulic force and it is internal to the transmission assembly. With that transfer of power comes excessive heat. The lockup torque converter was designed to make the transmission more efficient at highway speeds and to control heat. The torque convertor clutch is what lockups the convertor. Heat kills transmissions. That is why you hear that stop and go traffic is hard on a automatic transmission
The converter clucth does not lockup at these low speeds therefore heat is generated. This clutch is controlled by an electrical solenoid. The torque convertor clutch is locked changing the fluid coupling to a mechanical one. This solenoid uses power and ground sent through a coil of wires which creates a magnetic field to pull or push a central metal rod. When the solenoid is energized or de-energized, it directs fluid flow through the valve body of the transmission.
Symptoms P0743
1
Malfunction indicator illumination (check engine light or service engine soon light)
2
Stalling when coming to a stop after cruising speeds
3
Shudder on take off
4
Shudder when coming to a stop
Possible Causes P0743
1
Low or dirty transmission fluid
2
Wire/circuit issue shorted to power or ground
3
Failed torque converter clutch (TCC) solenoid
4
Failed TCC assembly in the torque converter
5
Failed PCM/ECM/EMC
Solutions & Repair Steps P0743
First you need to gather some tools together or borrow some (a rare occurrence with mechanics as our tools are our livelihood and we don't like to lend out our tools):
TIP: Remember in most cases there’s an internal transmission harness that connects the TCC solenoid and shift solenoids, so the wire fault may only happen when the transmission is hot or cold. Or, when the vehicle is driven above bumps or when making a turn. Make every attempt to recreate it! TIP: Before addressing any transmission issue make sure the engine is running in tip top shape! Address any other sensor codes or lean/rich codes first. There are a lot of sensors that are networked together that determine transmission shift scheduling. If one is "offline/faulty" then the ECM/PCM/EMC may be throwing this code through the fault it sees at another sensor. TIP: Many times a simple fluid and filter change will take care of minor transmission issues. There’s nothing to lose with a fluid and filter change. Notice I say change and not a fluid flush. A fluid flush on a high mileage transmission may cause further damage. Also, for a transmission that is slipping I recommend Lucas Oil Transmission Fix. I am not endorsing the product nor am I getting paid to use the name. But it works!
Good luck! In my case, I am a Ford trained technician and due to experience I simply pulled the transmission pan and took a look at the solenoid and found my problem right off the bat. This is a common issue on higher mileage transmissions.
TIP: Remember in most cases there’s an internal transmission harness that connects the TCC solenoid and shift solenoids, so the wire fault may only happen when the transmission is hot or cold. Or, when the vehicle is driven above bumps or when making a turn. Make every attempt to recreate it! TIP: Before addressing any transmission issue make sure the engine is running in tip top shape! Address any other sensor codes or lean/rich codes first. There are a lot of sensors that are networked together that determine transmission shift scheduling. If one is "offline/faulty" then the ECM/PCM/EMC may be throwing this code through the fault it sees at another sensor. TIP: Many times a simple fluid and filter change will take care of minor transmission issues. There’s nothing to lose with a fluid and filter change. Notice I say change and not a fluid flush. A fluid flush on a high mileage transmission may cause further damage. Also, for a transmission that is slipping I recommend Lucas Oil Transmission Fix. I am not endorsing the product nor am I getting paid to use the name. But it works!
Good luck! In my case, I am a Ford trained technician and due to experience I simply pulled the transmission pan and took a look at the solenoid and found my problem right off the bat. This is a common issue on higher mileage transmissions.