1. What is P0746 in Chevrolet Silverado?

The P0746 OBD-II code stands for Torque Converter Clutch (TCC) Pressure Control Solenoid Circuit Performance/Stuck Off. For the Chevrolet Silverado 1500 (2014-2023)—America’s top-selling full-size pickup—this code targets the TCC solenoid in the 6L80 6-speed automatic transmission (standard in 5.3L EcoTec3 V8-equipped LT, LTZ, and High Country trims).

The TCC solenoid regulates hydraulic pressure to the torque converter’s clutch, which locks the converter to the engine at highway speeds (60+ MPH) for better fuel efficiency (up to 22 MPG highway) and reduced transmission heat. P0746 triggers when the Silverado’s PCM (Powertrain Control Module) detects the solenoid can’t maintain target pressure—signaling a faulty solenoid, clogged valve body, or damaged wiring.

Silverado Specific Note: This code is widespread in 2016-2022 Silverado 1500s with the 6L80 transmission, per Chevrolet TSB 18-NA-355. The 6L80’s TCC solenoid (part #12680771) is prone to wear from heavy towing (max 12,500 lbs for 5.3L 4x4 models) and old transmission fluid (DEXRON-VI), which breaks down and clogs the solenoid’s valve.

2. Common Causes of P0746 in 2014-2023 Silverado

P0746 in Silverado 1500 6L80 models is tied to transmission component wear and fluid issues—below are real-world cases diagnosed with the ICARZONE UR1000:

• Faulty TCC Solenoid (2020 Silverado LT 5.3L): An LT owner with 85,000 miles reported high RPM at highway speeds. The UR1000’s TCC Solenoid Pressure Test showed 5 psi (normal: 35–45 psi). The solenoid’s internal valve failed (per TSB 18-NA-355)—replacing it with OEM #12680771 fixed P0746.
• Clogged Valve Body (2019 Silverado LTZ 5.3L): An LTZ owner’s P0746 reappeared after solenoid replacement. The UR1000’s Transmission Fluid Flow Test revealed restricted flow to the TCC circuit. Carbon deposits from old DEXRON-VI fluid clogged the valve body—cleaning with valve body cleaner (#ATP AT-205) resolved the issue.
• Damaged Solenoid Wiring (2017 Silverado High Country 5.3L): A High Country owner’s P0746 was intermittent. The UR1000’s Circuit Continuity Test found 18Ω resistance (normal: <0.5Ω) in the solenoid harness. Road debris frayed the wire—splicing with heat-shrink connectors (#Dorman 85518) restored voltage flow.
• Outdated PCM Calibration (2021 Silverado LT 5.3L): An LT owner’s P0746 appeared after a battery jump. The UR1000’s PCM Version Check showed outdated firmware (v1.8.0). Updating to v2.3.0 via UR1000’s "Chevy Transmission Calibration" tool fixed the solenoid control logic (addressed in TSB 21-003).

3. Key Symptoms of P0746 in Silverado 1500 6L80

P0746 symptoms in the Silverado are transmission-focused—watch for these signs that affect driving comfort and efficiency:

4. Silverado Trims/Transmissions Prone to P0746

Chevrolet service data highlights these 2014-2023 Silverado 1500 configurations with the highest P0746 occurrence rates (all paired with the 6L80 6-speed auto):

5. Diagnose P0746 with ICARZONE UR1000

Diagnose P0746 in your Silverado 1500 6L80 accurately with the UR1000’s Chevy-specific transmission tools. Follow these steps (engine off, key in "ON" position):

Case Example: A 2019 Silverado LTZ failed Step 3 (22 psi) and Step 5 (TSB 18-NA-355 eligible). The UR1000’s Component Location Tool guided solenoid access (remove transmission pan). Replacing the solenoid and flushing fluid fixed P0746—verified by highway test (RPM dropped to 2,000 at 65 MPH).

6. How to Fix P0746 in Silverado 1500 6L80

Resolve P0746 in your Silverado with these UR1000-verified solutions—tailored to the 6L80 transmission:

1. Replace Faulty TCC Solenoid (Most Common Fix for TSB 18-NA-355)

1. Confirm solenoid failure via UR1000’s Step 3. Raise the Silverado with jack stands (secure to frame rails) and drain transmission fluid (remove pan drain plug).
2. Remove the transmission pan (18 10mm bolts) and filter (3 bolts). Locate the TCC solenoid: Mounted on the valve body (passenger-side, 2-pin connector).
3. Disconnect the solenoid’s electrical connector and remove the 2 mounting bolts (8mm socket). Pull the old solenoid straight up to remove it.
4. Install an OEM TCC solenoid:
   • 2014-2020 Silverado: #12680771
   • 2021-2023 Silverado: #12699317 (updated valve design)
5. Reinstall the filter, pan (replace gasket), and refill with DEXRON-VI fluid (6–7 quarts). Torque pan bolts to 18 ft-lbs.
6. Clear P0746 with UR1000 and test drive—verify TCC lockup at 60+ MPH (RPM drops ~800 RPM when locked).

2. Clean Clogged Valve Body

1. Confirm valve body clogs via UR1000’s Step 3. Follow Step 1–2 above to remove the transmission pan and filter.
2. Remove the valve body (10 10mm bolts) and inspect for carbon deposits (black buildup on TCC circuit passages).
3. Clean the valve body with transmission valve body cleaner (#ATP AT-205):
   • Spray cleaner into TCC passages and scrub with a soft-bristle brush.
   • Rinse with clean DEXRON-VI and dry with compressed air (low pressure).
4. Reinstall the valve body (replace gasket), filter, and pan. Refill with DEXRON-VI fluid.
5. Run the UR1000’s Transmission Adaptation Reset to recalibrate TCC lockup. Clear P0746 and test drive.

3. Update PCM Firmware (TSB 21-003)

1. Confirm outdated firmware via UR1000’s Step 5. Ensure the Silverado is parked in a well-ventilated area (update takes 20–25 minutes).
2. Connect the UR1000 to the OBD-II port and select "Chevrolet" > "Silverado 1500" > "PCM" > "Firmware Update."
3. The UR1000 will detect the current PCM version and download the latest update (matches TSB 21-003 specs).
4. Do not turn off the engine or disconnect the UR1000 during the update. The tool will alert you when complete.
5. Restart the engine, run the transmission adaptation reset, and clear P0746. Verify TCC pressure via UR1000 (should read 35–45 psi).

7. P0746 Repair Costs & Maintenance Tips

P0746 repair costs for the Silverado 1500 6L80 vary by cause. Use this table to budget:

Maintenance Tips for Silverado 1500 6L80 Owners

• LT/LTZ (towing users): Replace the TCC solenoid every 80,000 miles (preventive) — use OEM #12680771 to avoid TSB 18-NA-355 failures.
• Change transmission fluid every 60,000 miles (use only DEXRON-VI). Old fluid breaks down and clogs the TCC solenoid/valve body—triggering P0746.
• Inspect the solenoid harness during fluid changes—secure it away from heat sources (exhaust) with zip ties to prevent wiring damage.
• Avoid "lugging" the transmission (low RPM + heavy load). Shift to a lower gear when towing >8,000 lbs to reduce TCC solenoid strain.
• Perform the UR1000’s Transmission Health Check every 15,000 miles — monitor TCC pressure and voltage to catch issues before P0746 triggers.

8. Silverado-Specific FAQs