2015 Chevrolet Silverado 1500 - Hard Shifting 1-2 and 2-3

Question

My Silverado has been shifting extremely hard between 1st and 2nd gear, and sometimes 2nd to 3rd. It feels like I'm getting rear-ended. It only happens when the transmission is up to operating temperature (around 190-200 F). When cold, it shifts like butter.

I checked the fluid and it's a bit dark but doesn't smell burnt. No metal shavings on the dipstick. There are no CEL codes or pending codes. The truck has the 6L80 transmission with about 110,000 miles on it. Is the torque converter failing?

ScannerSandy · Answer

✅ Confirmed fix: The issue was the Transmission Fluid Temperature sensor and the internal wiring harness (Lead Frame). It was sending erratic temp readings causing the Line Pressure Solenoid to Max out pressure as a fail-safe. Replaced the internal TEHCM (Transmission Electronic Hydraulic Control Module) and the shifting returned to normal. Also installed a lower-temp thermostat for the trans cooler to keep temps under 150F.

CoolantKai · Answer

This is a classic symptom of the 6L80 adaptive learning gone wrong. Try a 'Transmission Adaptive Pressure Reset' using a high-end scan tool like a Snap-On or Autel. Often the computer is compensating for wear but overshoots the pressure, causing the harsh engagement.

2015 Chevrolet Silverado 1500 - Hard Shifting 1-2 and 2-3

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