AutoCodes – Toyota – P0743 Toyota

P0743 Toyota Code - Torque Converter Clutch Circuit Electrical

Quick Answer

The Torque Converter Clutch (TCC) is designed to increase efficiency by mechanically coupling the engine to the transmission. Common causes include Dirty transmission fluid, Low transmission fluid level, Faulty Torque Converter Clutch (TCC) Solenoid Valve. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0743 Toyota indicates Torque Converter Clutch Circuit Electrical.
Common causes: Common causes include Dirty transmission fluid, Low transmission fluid level, Faulty Torque Converter Clutch (TCC) Solenoid Valve.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 13,358

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Dec 27, 2021

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code P0743 Toyota Description

The Torque Converter Clutch (TCC) is designed to increase efficiency by mechanically coupling the engine to the transmission. The TCC solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Lock-up piston operation will then be controlled. When the torque converter clutch solenoid valve is activated, the torque converter lockup clutch will engage creating a 1 to 1 RPM ratio between the transmission input shaft and the rotational speed of the torque converter. The lock-up operation, however, is prohibited when A/T fluid temperature is too low. When the accelerator pedal is depressed (less than 2/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up. By performing a voltage drop test, the ECM detects that the Torque Converter Clutch (TCC) solenoid circuit is open or shorted and sets the Diagnostic Trouble Code (DTC).

OBDII Code P0743 Toyota - Torque Converter Clutch Circuit Electrical - AutoCodes.com — P0743 Toyota Code - Torque Converter Clutch Circuit Electrical

What does this mean?

What are the Possible Causes of the DTC P0743 Toyota?

Dirty transmission fluid
Low transmission fluid level
Faulty Torque Converter Clutch (TCC) Solenoid Valve
Torque Converter Clutch Solenoid Valve harness is open or shorted
Torque Converter Clutch Solenoid Valve circuit poor electrical connection

How to Fix the DTC P0743 Toyota?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

This is an electrical problem code. Could be a problem with the harness to the Torque Converter Clutch (TCC) solenoid, the TCC solenoid connector, or the TCC solenoid itself.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0743 Toyota code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.