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Home >> Chevrolet >> 2018 >> Suburban 3500 HD LT >> Repair and Diagnosis >> External Pages >> Different car >> Section 21 (Automatic Transmission - 10L80 (MF6) - Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> Harsh Garage Shift

Harsh Garage Shift

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Checks Causes
NOTE:

On cold days, approximately 32°F (0°C) or colder, the transmission is designed to shift differently. The transmission uses a warm-up mode shift schedule until the engine reaches normal operating temperature. While the transmission is in warm-up mode, it is normal for transmission upshifts to be delayed or held longer. This feature improves heater performance by giving quicker vehicle warm-ups.

Engine Elevated engine RPM - Verify correct engine operating rpm per application.
Control Solenoid (w/Body and Valve) Valve Assembly (12)
  • Incorrect or inadequate adapt activity - Perform Q77 Transmission Control Solenoid Valve Characterization Programming procedure.
  • Incorrect TCM temperature reporting - Monitor TCM temperature using Tech 2.
  • Line pressure control solenoid incorrect pressure.