Harsh Garage Shift

Automatic Transmission - 10L80 MHS MQC | Diagnostic Information and Procedures | Document ID: 4572738

Checks 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.	Causes
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 appropriate scan tool. Line pressure control solenoid incorrect pressure.

Checks 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.

Causes

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 appropriate scan tool. Line pressure control solenoid incorrect pressure.