P0743 on GMC
Torque Converter Clutch Circuit Electrical
P0743 on GMC vehicles indicates torque converter clutch circuit electrical. Au7o has documented this code across 1 GMC model — most commonly on Sierra 3500HD. This code indicates an electrical fault in the torque converter clutch (TCC) circuit, the wiring and solenoid that lock the torque converter so the engine and transmission turn together for better efficiency at cruising speed. The transmission computer commands the TCC solenoid on and off, and when it sees an open, short, or out-of-range electrical signal in that circuit, it sets this code. You may notice slipping, harsh or no lockup, reduced fuel economy, or the transmission staying in a lower gear. Because it is an electrical-circuit code, the problem is usually in the solenoid, connector, or wiring rather than worn mechanical clutch material. Typical repair costs on GMC range from $150 to $2,200, depending on the specific model and root cause.
Common Causes of P0743
- •Failed torque converter clutch (TCC) solenoid
- •Open, shorted, or corroded wiring in the TCC circuit
- •Damaged or loose transmission connector
- •Low or contaminated/dirty transmission fluid
- •Faulty transmission valve body or internal harness
- •Failed torque converter (internal clutch)
- •Faulty transmission control module (TCM/PCM)
P0743 on GMC by Model
GMC Sierra 3500HD(1 issue)
- Allison 1000/2000 Series Transmission Torque Converter Shudder2007-2020
The Allison 1000 and 2000 series automatic transmissions paired with Duramax engines in the Sierra 3500HD exhibit torque converter clutch shudder during light throttle cruising between 40–65 MPH as the TCC applies and releases. This is caused by degraded transmission fluid, worn TCC friction material, or contamination in the hydraulic circuit. GM and Allison have acknowledged this issue through multiple fluid specification updates and TSB 07-07-30-022.
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What does P0743 mean on GMC?▼
P0743 stands for "Torque Converter Clutch Circuit Electrical." This code indicates an electrical fault in the torque converter clutch (TCC) circuit, the wiring and solenoid that lock the torque converter so the engine and transmission turn together for better efficiency at cruising speed. The transmission computer commands the TCC solenoid on and off, and when it sees an open, short, or out-of-range electrical signal in that circuit, it sets this code. You may notice slipping, harsh or no lockup, reduced fuel economy, or the transmission staying in a lower gear. Because it is an electrical-circuit code, the problem is usually in the solenoid, connector, or wiring rather than worn mechanical clutch material. On GMC specifically, this code is documented across 1 model.
What causes P0743 on GMC vehicles?▼
Common causes on GMC: Failed torque converter clutch (TCC) solenoid, Open, shorted, or corroded wiring in the TCC circuit, Damaged or loose transmission connector, Low or contaminated/dirty transmission fluid, Faulty transmission valve body or internal harness. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0743 on a GMC?▼
Repair costs on GMC range from $150 to $2,200, depending on the specific model and root cause.
Which GMC models have P0743 documented?▼
Au7o has documented P0743 on 1 GMC model: Sierra 3500HD.