This bulletin applies to 2012 Buick LaCrosse, Regal and Verano vehicles. Some customers may note a slip when reverse is selected or no reverse, a slip or flare when shifting into third gear or no third gear, a slip or flare when shifting into fifth gear or no fifth gear. The warning light may be with diagnostic trouble code (DTC) P0776 found as an active or a history code in the transmission control module (TCM).
Follow service manual diagnostics for DTC P0776. Select the appropriate Gen 1 or Gen 2 diagnostics. The Buick models use Gen 2 controls. The control solenoid valve and transmission control module assembly solenoid (TEHCM) performance test is functional and must be used as part of proper diagnosis.
Do not rely on an aircheck of the third-fifth clutch through the case oil feed ports as a reliable diagnostic test. Air testing through the case has been found to frequently lead to an incorrect diagnosis of the 3-5-R clutch piston condition. The only reliable method of diagnosing the condition of the 3-5-R clutch piston is transmission disassembly and visual inspection of the piston.
