Action Taken When the DTC Sets: P0975-P0977

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
If the fault occurs while in a forward range, a shift to 1st, 3rd, or 5th range is made.
While diagnostic response is active, if the shift selector is moved to NEUTRAL, the transmission will shift to NEUTRAL. If the shift selector is moved to REVERSE, the transmission will shift to REVERSE. If the shift selector is moved to a forward range or to REVERSE and the transmission is compromised by over-speeding or direction change, the transmission will shift to NEUTRAL.
DTC P0975, P0976, or P0977 is stored in TCM history.
Main modulation (MAIN MOD) is inhibited.
The TCM freezes shift adapts.
The TCM inhibits torque converter clutch (TCC) engagement.